application manual kf - titration - si analytics

Application Manual KF - Titration

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KF Titration Application Manual

Contents Page 1 Introduction............................................................................................................................................. 1 2 Main part................................................................................................................................................. 1

2.1 Basics of KF titration ....................................................................................................................... 1 2.1.1 The chemical reaction.............................................................................................................. 1 2.1.2 Side reactions .......................................................................................................................... 2 2.1.3 The influence of temperature and reaction medium................................................................ 3 2.1.4 Titration curves ........................................................................................................................ 5 2.1.5 Volumetry and coulometry ....................................................................................................... 6 2.1.6 „Setting“ the titration................................................................................................................. 7

2.2 Working methods of KF titration...................................................................................................... 8 2.2.1 Sample properties.................................................................................................................... 8

2.2.2.1 Working with liquid samples................................................................................................. 8 2.2.2.2 Working with solid samples.................................................................................................. 9 2.2.2.3 Dry-heating of samples using the oven................................................................................ 9

2.2.2 Adaptation to the sample matrix ............................................................................................ 10 2.2.2.1 Working with other temperatures ....................................................................................... 10 2.2.2.2 Variation of the commercially available solvent ................................................................. 11 2.2.2.3 Setting the pH value........................................................................................................... 12

2.3 Working specifications .................................................................................................................. 13 2.3.1 Titer determination ................................................................................................................. 13 2.3.2 Use of single-component reagents ........................................................................................ 14 2.3.3 Use of two-comonent systems............................................................................................... 15 2.3.4 Working with liquid samples .................................................................................................. 16 2.3.5 Working with solid samples and direct input.......................................................................... 17 2.3.6 Working with solid samples and solid lock............................................................................. 18 2.3.7 Working with solid samples and homogenizer ...................................................................... 19 2.3.8 Working with raised temperature ........................................................................................... 20 2.3.9 Working with external extraction............................................................................................ 21 2.3.10 Working with the oven............................................................................................................ 22

2.2.3.1 General form of working specifications .............................................................................. 23 2.3.11 Inspection of the titration system ........................................................................................... 24

2.4 Error and their consequences....................................................................................................... 26 2.4.1 The titration takes too long .................................................................................................... 26 2.4.2 The titration solution turns brown........................................................................................... 26 2.4.3 Detected water contents is too low ........................................................................................ 26 2.4.4 Detected water contents is too high....................................................................................... 27 2.4.5 Brown titration solution is leaking .......................................................................................... 27 2.4.6 Titration proceed fast and without stopping........................................................................... 27 2.4.7 Wrong output of the result ..................................................................................................... 27

2.5 Validation of the KF titration.......................................................................................................... 27 2.5.1 Validation scheme and evaluation of general features.......................................................... 28 2.5.2 Inspection of testing means ................................................................................................... 29 2.5.3 Tests to be made ................................................................................................................... 30

2.6 KF titration and normative documents .......................................................................................... 32 2.7 KF titration and quality assurance................................................................................................. 34

3 List of keywords.................................................................................................................................... 36 4 Annexes........................................................................................... Fehler! Textmarke nicht definiert.

4.1 Documents ............................................................................... Fehler! Textmarke nicht definiert.

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1 Introduction The water contents or the humidity is an important factor for many products, since it influences the product properties or the quality of the products. Butter, for instance, contains up to 16 % of water. If the water contents is too high, butter does no longer meet the legal regulations. In this way, the microbiological composition is exposed to considerably higher risks. If the water contents is too low, the manufacturer simply gives away money. The determination of the water contents, in addition to its mere necessity, is in many cases an important commercial factor to reduce costs.

There are countless applications in which the water determination is inevitable: The pourability of products, the processing of plastics in injection moulding, or else, tablets will disintegrate if they are too dry, or they will deliquesce if they contain too much humidity. This list could be continued without ever reaching an end.

In this context, the water contents may be located in the ppm range, such as is the case with insulating oil, or in a high percentage range, for instance in the case of alcoholic extracts of natural matters (plants). Karl Fischer titration with its methods can cover this wide sector without any problems.

Karl Fisher reaction was published in 1935 by Karl Fischer as a method of water determination. He used pyridine, iodine, methanol, and SO2 as single-component compounds for his determinations. The underlying reaction equation was based on Bunsen’s equation. Stoichiometry of the reaction equation, however, was corrected in subsequent publications.

A titration can only be performed if the end point of the reaction is clearly marked or if the reaction is recorded in the form of a titration curve and the transformation can be calculated on this basis. In the case of Karl Fischer titration the end of the titration can be seen in the colour change to brown, caused by the iodine surplus. The own colour of the reaction, however, does not change in the course of the titration. Whereas the first titration clearly shifts from almost colourless to dark brown, the colour shift of many titrations may be from dark yellow to brown. This is based on the assumption that a multitude of samples is being titrated in one and the same solution. This is common practice today.

Modern titrators recognise the end of titration in an electrochemical way. In the case of Schott titrators, the indication is done in a bi-amperometric process. A voltage is applied between two platinum pins. As long as water is present in the solution, only iodide is present in the solution, and no current is flowing. As soon as the water is titrated away, the solution contains a small iodine surplus. The oxidation of the iodide to iodine occurring at the anode, and the reduction of the iodine to iodide occurring at the cathode is reversible and indicated by a flow of current.

2 Main part

2.1 Basics of KF titration 4.1.1 The chemical reaction The precise nature of the mechanism of Karl Fischer reaction was the subject of tedious discussions. Even the stoichiometry of the reaction was not clear for a long time. In principle, titration would not be possible with it. Recently, the mechanism has been the object of several investigations which resulted in the following reaction equation: ROH + SO2 + RŃ [RŃH]SO3R H2O + J2 + [RŃH]SO3R + 2 RŃ [RŃH]SO4R + 2 [RŃH]J Equation 1: KF equation according to [1]

Legend: ROH An alcohol, for instance, methanol, ethanol, ethylene-glycol-mono-ethyl-ether RŃ A caustic solution, for instance imodazol (formerly often pyridine The investigations of the mechanism show a change in stoichiometry if work is done in other solvents. The addition of other solvents should therefore be limited to 50 volume %.

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The basic components of the reaction are as follows: • Alcohol • Base • SO2 • Iodine

A distinction in 2 fundamental working techniques is made: Either all components are combined within one titration reagent (single-component reagent), or else, alcohol, base, and SO2 are patterned in a solvent component and titrated with iodine in alcohol (two-component reagent). Since, in contrast to the single-component reagent, base and SO2 are present in a surplus in the case of the two-component reagent, and since the system is moreover buffered, the reaction is clearly quicker. To achieve this effect for the single-component reagent, too, an additional auxiliary solvent is added in some cases.

The single-component reagent is mainly used to enable special samples to be dissolved by a variation of the solvent. With many polar samples, formamide is added, whereas chloroform is added with many non-polar samples. It is also possible to add long-chained alkanes or alcohols. Any addition of other solvents to alcohol should not exceed 50 volume %.

Intense investigations show the pH dependency of the reaction, and this is to be expected before the background of the reaction equation. The optimum pH is between pH 6 and 7. If the pH is lower, the reaction speed will slow down clearly. And if the pH value is higher than pH = 8.0, side reactions will give the illusion of an excessive consumption.

Therefore please note: • When determining acids, check the pH value and add imidazol if required. • When determining bases, neutralise using benzoic acid or salicylic acid.

4.1.2 Side reactions In the given the circumstances, KF titration is water selective to a far-reaching extent. Nevertheless, there is of course a number of restrictions caused by a series of side reactions. These side reactions can be classified according to the following types. a) Reactions producing water

b) Reactions requiring water

c) Redox side reactions of the iodine

d) External water

Some examples will be quoted here. In many cases, the side reactions can be avoided by corresponding working conditions or an appropriate selection of the reagents.

a) Reactions producing water The best known water-producing reaction is the formation of acetals and ketals. The alcohol required for this reaction and used as the solvent reacts with carbonyl groups (C=0) under formation of water. This water is also captured in the titration. The titration seems to be endless. The result is a high permanent "drift".

• Alcohol • Base • SO2 • Iodine

Single-component reagent 2-component reagent

• Alcohol • Base • SO2 • Iodine

• Alcohol

Pattern Titration agent

• Methanol

Pattern Titration agent

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The formation of acetals or ketals can be avoided, however, if special reagents for aldehydes and ketones are used. An alternative possibility would consist in working at a reduced temperature. In this case, work is done at temperatures below 0°C. The ionic KF reaction proceeds almost unaffected, while the formation of acetals or ketals is clearly slowed down. The lower temperature limit is determined by the viscosity of the pattern and the settlement by crystallisation of side components. Under certain circumstances, aldehydes may also enter into a bi-sulfite addition with SO2. If the pH value is correctly set, this reaction should be largely suppressed. This reaction would not produce or bind any water, but reduce the available SO2 quantity.

Other reactions involving the formation of water include the reaction of carbonyles with amines to form Schiff’s bases, the formation of enamines, and the esterification of acids with the alcohol of the solvent. If methanol-containing solvents are used, the risk is reduced.

In the case of certain neutralisation reactions with the bases, water giving the illusion of an increased water contents may be formed.

b) Reactions requiring water Ester decomposition would be a typical reaction requiring water. A temperature decrease should solve the problem. This problem is hardly of any practical importance, since most esters do not react under the conditions of KF titration.

c) Redox side reactions of the iodine This involves a series of possible reactions. Peroxides react with iodine [1, 2]. Other oxidants such as chlorine, nitrogen oxides, dichromate have to be reduced before use. Reductives such as ascorbic acid, tin(II)-salts, and mercaptan have to be oxidised prior to titration. [1, 2] contains a description of numerous side reactions and possible solutions.

d) External water External water is the most frequent source of error with KF titration. There are various possible causes for its entrance into the titration cell. As a matter of course, the solvent or the pattern component have to be dry-titrated first. This process is referred to as conditioning. If water still enters the titration cell, it is assigned as external water together with the sample. External water enters the titration cell in one of the following ways: • A titration cell is not tight. External particles, for instance, may be stuck in the ground surfaces. • Defective O-rings at the screwed connections of the titration cell may be another possibility. • The septum for the addition of liquid samples is not tight and worn out. • The molecular sieve in the drying tube for pressure equalisation is used up and has to be dried. • The pumping system contains damp air. The air for the addition of the solvent should also be dried

using a molecular sieve.

4.1.3 The influence of temperature and reaction medium The Karl Fischer reaction is a fast reaction. It depends much less on the temperature than a lot of the side reactions. The acetal and ketal formation, for instance, is reduced by a decrease of the temperature to such a degree that a Karl Fisher water determination is still possible in many cases. By suitable cooling facilities, the temperatures can be reduced down to – 30 to – 40 °C. The possible cooling agents include: dry ice with a matching organic solvent, ice/salt mixtures, or the connection of a cryostat to a temperature-controllable titration vessel. The increased duration of the titration with temperatures as low as these remains practicable if work is done with two-component reagents.

Titration at increased temperatures is mainly used to improve and accelerate the process of dissolving a sample or to extract the water from a sample more speedily. The temperatures can be regulated to 40 – 50 °C without any problems. If the temperature is further increased, a cooler is to be used in the position of the drying tube. The drying tube is then placed on top of the cooler. Temperature equalisation is simply done by using a small, heatable magnetic stirrer which is placed under the titration cell.

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The titer of the titration agent will change if the working temperatures clearly differ from 20 °C. Literature quotes a titer change of 1 % per 10 °C [2]. In principle, it is recommended to determine the titer under the same conditions under which the sample is titrated.

In addition to the variation of the temperature, the use of different solvents enables an adaptation to the matrix. Considering that the alcohol participates in the chemical reaction, it cannot be fully substituted. The alcohol components used include: methanol, ethanol, 2-chloroethanol, ethylene-glycol-monomethyl ether. Owing to its solubility properties, methanol can be used on a broad basis, but is classified as poisonous (poison class 3). Likewise, some of the alternatives are poisonous, and if used, the required safety measures have to be taken. They are indicated on the reagent bottles (R and S sentences).

The alcohol component should be contained by a minimum of 50 % in the titration cell. Other solvents are added to improve or enable the solubility of samples:

Solvents Application Observations

Formamide Polar substances, sugar, salts, proteines

Please observe hazards information and safety advice! Formamide can cause damage to the unborn child!

Chloroform, dichloromethane

Fats/greases, oils, hydrocarbons

Please observe hazards information and safety advice!

Long-chained alcohols, 1-propanol, 1-butanol, decanol



Alkanes (ligroines, petrol ether)



Ethylene glycol Absorption of gases Please observe hazards information and safety advice!

Acetic acid Amines, inorganic compounds


Toluene, Xylene Plastics, lubricating fats/greases, oils


The use of formamide and chloroform accelerates titration, but may change the titer in the process. In this case, too, it is generally valid that the titer has to be determined under the same conditions under which the sample is later on titrated.

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4.1.4 Titration curves KF titration is controlled by the magnitude of

• the current flow between the platinum pins of the electrode [µA] • the reagent consumption [ml] • the duration of the titration [s]

The current curve is required for the indication of the titration end. In addition, the titration control tries to titrate as quickly as possible after a check at the beginning of titration, in order to hit the endpoint of the titration as accurately as possible when the end of the titration is approaching.

KF titration current curve

0

5

10

15

20

25

0 1 2 3 4 5

Titration agent [ml]

Stro

m [µ

A]

Fig. 2: Current curve of a KF titration

Figure 2 shows an indication curve showing the consumption on the x axis and the current in µA on the y axis. The almost completely flat course of the current curve with a sudden rise towards the end of titration is typical. Considering that this curve gives only little information on the reaction, it makes sense in practice to record that time versus consumption. On the x axis, the time is recorded, whereas the y axis shows the consumption as a function of time (Figure 3).

KF titration curve

0

1

2

3

4

5

20 40 60 80 100 120 140

Titration duration [s]

Verb

rauc

h [m

l]

Fig. 3: Current curve of a KF titration

As you can see from the curve, approx. 95 % of the titration agent have been dosed within approx. 50 seconds after approx. 20 seconds of solving or extraction time. In the course of the remaining 70 seconds, titration was performed carefully and in minute quantities in order to achieve a result as accurate as possible. Titration will end as soon as no more reagent is being titrated within a defined period of time (mostly 10 or 20 seconds).

The following criteria are indicative of a "good" titration curve: Steep rise means fast titration (too flat = too slow) • A round, but not too steady bow without bends (too round = too slow; bend = overtitration) • A flat course, parallel with the x axis (further rise = drift).

Flacher, paralleler Verlauf zur x-Achse

Nicht zu scharfer Knick

Steile Kurve

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KF titration curve with a clear drift caused by side reactions

0

0,5

1

1,5

2

2,5

20 70 120 170 220 270Time [s]

Verb

rauc

h [m

l]

Fig. 4: KF titration curve with a clear drift caused by side reactions

The high drift may be indicative of a side reaction or of a leaking titration cell. From the example in figure 4 you can see a titration curve which is characterised by a high drift of approx. 240 µl/min caused by side reactions. The proportionate consumption of the sample can be read off on the y axis by a backward extension of a straight line leading through the rise of the drift. In the present example, the side reaction was caused by a too high pH value (< pH 8).

4.1.5 Volumetry and coulometry KF titration can be performed in two different ways: in a volumetric or in a coulometric process. The reaction equation and the indication of the titration end are the same in both cases. The difference is found in the addition of the iodine solution. Whereas, in the case of volumetric titration, the reagent addition is done automatically using a motor-driven piston burette of the titrator, the reagent is generated electrochemically from iodide in the case of coulometry.

The practically relevant differences are derived directly there from:

Volumetry Coulometry Reagents with different concentrations are available (1, 2, 5 mg/ml)

Iodine generation according to Faraday’s law, electrochemically

For all quantities from 0.5 mg of water For small quantities of water only Solid, liquid, and gaseous samples Liquid and gaseous samples A variation of the solvent is possible A variation of the solvent is hardly possible Certain samples can be titrated in one and the same cell without change of solvent

A great lot of samples can be titrated one after the other in the same solvent

Titration to dry of the cell will occur very quickly

The drying process of the cell and the solvent will take very long, since the newly generated quantity of the reagent is only small

Used as: Universal method

Used as: Micro method

The smallest quantity of water which can be determined by way of volumetry can be derived easily by some reflections: • Smallest dosable reagent volume: 0,5 ml (works very well in practice) • Titer of the reagent: 1 mg water / ml • Soluble sample quantity: 10 g

In many cases, this is still practicable without any problems. If the solubility of the samples becomes worse, i.e. if less sample can be used, consumption decreases. With some practice, sensible results may still be achieved with a consumption of 0.1 ml.

Hohe Drift von ca. 240 µl/min zeigt Nebenreaktion

Verbrauch ohne Drift

Drift mit kontinu-ierlichem Anstieg

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The following table shows the relationships between water contents, sample quantity under the above conditions:

Sample quatity [g]

Consumption [ml]

Titer [mg/ml]

Water content [ppm]

Water content [%]

0.05 10 5 1 000 000 100 0.1 5 5 250 000 25

1 5 5 25 000 2.5 1 5 2 10 000 1.0 1 1 2 2 000 0.2 1 1 1 1 000 0.1 1 0.5 1 500 0.05

10 0.5 1 50 0.005 So the smallest water contents which can be titrated volumetrically is approx. 50 ppm, the highest is 100 %.

4.1.6 „Setting“ the titration In principle, KF titration requires three different "methods": • Titer determination to establish the exact concentration of the titration agent. By way of a titration

using an accurate standard, the exact concentration of the titration agent is determined. The concentration of the titration agent is subject to changes over time. The titer determination should be repeated approx. every week.

• Blank value: Determination for working with the oven or for longer opening times of the titration cell. A blank value is particularly required for samples which are heated to dry using an oven. As a result of the gas flow through the oven, atmospheric water is entrained, thus leading to a blank value. If the sample is heated to dry for approx. 10 minutes, the blank value of approx. 10 minutes should be deducted from the titration result.

• Sample titration for the determination of the water contents of the samples. This is the actual method for determining the water in a sample.

These "methods" are distinguished by the formula, but not by the setting of the parameters. The settings of the parameters involve:

• Breaking current in [µA] ; if this current is flowing between the indicator electrodes, the end criterion has been reached.

• The default setting is 20 µA. Values from 10 – 30 µA make sense. • Switch-off time in [s]; if the breaking current has exceeded this switch-off time, the titration will be

ended. • The default setting is 10 s. Time spans between 0 – 10 s make sense. With a few special applications,

e.g. applications involving the introduction of gases, other settings may make sense. • Drift in [µl/min]; titration will be ended as soon as the addition of the titration agent falls short of the set

drift value. The default setting is 10 µl/min. Values from 3 – 30 µl/min make sense. • Applied voltage between the platinum electrodes in [mV]: As a rule, this value does not have to be

changed. The default setting is 100 mV. Values between 20 – 150 mV make sense. • An adaptation to the sample matrix is made possible by the extraction time in [s], to ensure a complete

water yield of the sample. Values between 10 and 600 s make sense. • An adaptation to the sample matrix is made possible by the max. titration duration in [s]. In this way, a

KF titration can also be made possible with a high drift. A titration should not last longer than 10 minutes.

• The min. titration duration in [s] will accelerate the extraction of the water, without there being the risk that the titration is cancelled prematurely. The extraction behaviour is improved by a continuous addition of the iodine.

For all of these parameters, meaningful settings are defaulted on the TitroLine KF Titrator, so that hardly any change of these values is required. All settings should possibly be the same for a certain type of application, since otherwise the results cannot be compared exactly. The titer may change by differing settings of the parameters.

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2.2 Working methods of KF titration 4.2.1 Sample properties The working methods of KF titration are highly dependent on the properties of the sample. Working with gaseous, liquid, low-viscous, high-viscous, and solid samples is distinguished by: • Sample input • Solubility • Sample quantity • Sample volume • Water yield

2.2.2.1 Working with liquid samples In general, liquid samples are injected through a septum into the titration cell using a one-way syringe. The size of the syringe depends on the sample volume. Syringes from 1 ml to 20 ml can be used. The needles of these syringes have a diameter from 0 .6 to 1.2 mm. The thinner needles are or only available for low-viscous samples, whereas the thicker needles should be used for samples with a higher viscosity. The thicker the needle is, the higher will be the degree of the effect on the septum. In this case, it has to be replaced sooner. The length of the needles is between 50 and 90 mm. In this way it can be ensured that no drops remain adhered to the walls. The needles should not be immersed into the solvent. Particularly high-viscous samples, such as oils, are transferred into the titration cell without a needle, directly, and without the use of a septum.

The septum consists of a polymer which has to have the three following major properties: • The proper size. • It has to close again directly after being pierced. • This point can only be realised with certain restrictions. The silicon discs used have to be replaced on a

regular basis.

We recommend the use of original spare parts. As a rule, the samples have to be weighed in using an analytical weighing-balance. The working process is as follows: ⇒ Put a 150 ml beaker glass on the balance. ⇒ Draw up the liquid sample into the syringe. ⇒ Put the needle protector on again. ⇒ Place the syringe with the needle up into the beaker glass. ⇒ Gauge the weighing-balance. ⇒ Carefully take the syringe from the balance, then remove the needle protector. ⇒ Inject the sample through the septum into the titration vessel. ⇒ Remove the syringe from the septum, put on the needle protector again. ⇒ Place the syringe with the needle up in the beaker glass on the weighing-balance. ⇒ Read off the weight as a negative number on the weighing-balance, then enter it as an absolute value

on the titrator. Working with sample volumes is unusual. When drawing up the sample into the syringe, please proceed carefully and slowly to avoid air (including air-borne humidity) being unnecessarily drawn through the samples. Figure 5 shows the sample opening with the septum and a syringe:

Septum Needle

Cover

Plug

Fig. 5: Sample input through septum

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2.2.2.2 Working with solid samples The following working methods are common for solid samples: • Direct sample input by opening the plug in the cover of the titration vessel • Use of a solid lock

Direct sample input by opening the plug is certainly the most simple way of introducing solid samples in the KF titration vessel. During the opening time of the cell, humidity of the ambient air may lead to a blank value. This blank value, however, can be determined by way of a separate titration and then be automatically taken into account in arithmetic form. The smaller the water quantity to be determined, the less favourable is this method of sample addition. As a rule, the blank value should not be greater than the water quantity to be determined.

The samples may be weighed with a weighing boat made of glass or aluminium to be transported to the titration vessel. After weighing, the samples are no longer touched by hand.

Using the solid lock, it is possible to re-condition after the titration vessel was opened, prior to introducing the sample in the solvent. The sample quantity is limited to small sample quantities in the range of one gram. The working sequence is based on the following scheme: ⇒ The sample is weighed inside the solid lock. ⇒ Pull the outer part of the solid lock over the inner part containing the sample, until the part containing

the sample is fully closed. ⇒ Open the titration vessel, then place the outer part of the solid lock with the built-in NS 19 ground

surface in the opening. ⇒ Start conditioning. ⇒ Push down the inner part, so that the sample can be dissolved away. ⇒ Start titration with a longer extraction time for solving the sample. As an alternative, a minimum titration

duration can be specified.

Working with the solid lock may involve a higher drift. This can be taken into account accordingly in the titration methods.

2.2.2.3 Dry-heating of samples using the oven In many cases a direct determination is impossible because: • The samples are insoluble (plastics). • The samples release the water only in heat. • The samples enter into side reactions.

The samples are placed in the oven, heated up, and the water being released is transferred to the titration vessel by dried gas. In this process, the major quantity of water is released at the beginning. The following graph shows the way in which the water contained in the sample is released. At the end of titration, the added quantity is limited by the drift value. On the graph, a side reaction is indicated by a high residual drift. The x axis shows the duration of the titration, the first y axis shows the drift, the second y axis shows the consumption.

After a approx. five minutes, the major part of the water is released. We recommend a dry-heating time of 10 minutes. This time is set as a waiting time on the titrator. Subsequently, the water quantity absorbed in the solvent is titrated within a short period of time. If the preceding drift is not reached again, or almost not reached again, this is indicative of a side reaction.

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With the titration in the graph it was proven that thermal decomposition leads to the generation of formaldehyde, which reacts with the methanol in the titration cell to acetal, with water being separated.

Water yield

0

50

100

150

200

250

300

1 6 11Time [min]

Was

sera

bgab

e [µ

l/min

]

00,2

0,40,6

0,81

1,21,4

Verb

rauc

h [m

l]

The set-up and the connection of the oven will be illustrated by the figure below:

The gases to be preferred include inert gases, such as nitrogen, since side reactions, e.g. oxidations, cannot occur.

The set-up and the connection of the oven will be illustrated by the figures below.

(Hier die Anleitung Ofenanschluss)

4.2.2 Adaptation to the sample matrix The sample matrix has a major influence on the water determination. Direct water titration is not possible in all cases. Some samples release the water only very slowly or, under certain circumstances, do not release it at all. The possibilities for getting the water out of the samples in a definable form include, for instance: • The variation of the temperature • Comminution • Internal or external extraction • Variation of the solvent • Setting the pH value • Oven

2.2.2.1 Working with other temperatures A variation of the temperature of KF titration is simple method to: • Slow down temperature-dependent side reactions in such a manner that the KF titration can run off

without disturbance • Improve the input of volatile substances • Accelerate the extraction of the water contained in samples at a higher temperature • Accelerate titration

At low temperatures, many organic reactions go off clearly slower. KF titration is not that temperature-dependent. This means, for instance, that many ketones and aldehydes can still be titrated which would tend to disturbing side reactions at normal temperature. Cooling may be done by the external application of ice or by organic solvents with dry ice.

One problem of cooling is the condensation of atmospheric air during the process of opening the cell. It is therefore recommendable to work with a syringe through the septum or, in the case of solid samples, with a solid lock.

N2 Drying Oven Titration cell

11

Working at raised temperatures is opposed to this. The high air temperature enables a better extraction of water from the samples. Moreover, the reaction is speeded up. The most simple way of heating is the use of a heatable magnetic stirrer. Working without an additional cooler is possible in a temperature range from 40 – 50 °C. Methanol boils at approx. 65 °C. A reflux cooler can be set into the NS 14.5 ground opening of the dry air capillary. Subsequently, the desiccant tube is set on top of the cooler.

Pre-drying of the cooler in the drying oven is not required. If overtitration occurs during conditioning, for instance caused by a short-term removal of the electrode from the solution, the entire titration vessel plus the cooler can be "rinsed" with this solution. Particular care should be taken in this process. All apertures are to be closed (with plugs). Please observe all safety regulations applicable to the handling of the chemicals being used and the work in the laboratory. After the "rinsing" process, the plugs have to be replaced by desiccant tubes!

Particular care should be taking to ensure the thorough drying of the desiccant. Best results were achieved using a molecular sieve of the 0.3 nm size, which was dried in the drying oven at approx. 250 °C for at least three hours. A possibly present indicator reacts clearly too late. Replacing and drying on a regular basis will ensure a low drift inside the titration vessel.

2.2.2.2 Variation of the commercially available solvent As was already mentioned in Chapter 2.1.3., the adaptation of the solvent to the sample properties enables many applications to be performed which would otherwise be excluded from classic KF titration. The table in Chapter 2.1.3. provides some information on this topic. In many cases, additives to the reagents mentioned below are also possible. In case of doubt, please contact the manufacturer.

The manufacturers offer a number of commercially available solvents for specific applications: Manufacturer Solvent Application Observations

Hydranal Solvent E Lösungsmittelkomponente zu dem entsprechenden Titrier-mittel Hydranal Titrant 5 E

Hydranal Solvent Lösungsmittelkomponente zu dem entsprechenden Titriermit-tel Titrant 2/5

Hydranal Composolver Lösungsmittel für die Titration mit Hydranal Composite 1/2/5

Beschleunigt die Titration und ergibt bessere Resultate

Hydranal Methanol dry Besonders trockenes Methanol Absorbiert besser Wasser, benötigt weniger Reagenz zum Konditionieren

Hydranal Solvent Oil Löst viele Öle und Fette Chloroform frei Hydranal Solvent CM Löst die meisten Öle und Fette Enthält halogenierte

Kohlenwasserstoffe Hydranal Ketosolver Lösungsmittel für Ketone und

Aldehyde Ohne halogenierte Kohlenwasserstoffe

Riedel de Haen

Hydranal Arbeitsmedium K

Lösungsmittel für Ketone und Aldehyde

MERCK Karl-Fischer-Reagenz S Lösungsmittelkomponente zu dem entsprechenden Titriermit-tel Karl-Fischer-Reagenz T (TU)

Karl-Fischer-Reagenz SF

Löst die meisten Öle und Fette Enthält halogenierte Kohlenwasserstoffe

Karl-Fischer-Reagenz SK

Lösungsmittel für Ketone und Aldehyde

Methanol getrocknet Besonders trockenes Methanol Absorbiert besser Wasser, benötigt weniger Reagenz zum Konditionieren

12

Manufacturer Solvent Application Observations Fisher AquaStar Anhydrous

Methanol Besonders trockenes Methanol Absorbiert besser Wasser,

benötigt weniger Reagenz zum Konditionieren

AquaStar Solvent KN Lösungsmittelkomponente zu dem entsprechenden Titriermittel Comp 5/2K

AquaStar Solvent S Lösungsmittelkomponente zu dem entsprechenden Titrier-mittel Titrant 5

Important note: These solvents can normally only be used together with the appropriate titration

agents. It is not possible to use the methanol as a solvent and to titrate using a two-component titration agent. In this case the S02 base components are mis- sing, without which a KF reaction cannot take place!

2.2.2.3 Setting the pH value In Chapter 2.1.1 point, reference is already made to the pH-dependency of KF titration. The KF reaction requires a base to be functioning at all. The original composition used by Karl Fischer included pyridine, allegedly because it was just standing on the shelf. Pyridine has a pKs value of 5.25 and thus leads to a solvent which has a too low pH value for a fast reaction. Imidazol, which is often used today, has a pKs value of 6.95, and this means that a favourable pH value for a speedy titration is set. Other bases with comparable pKs values are also possible. The use of imidazol as a base for KF titration is under patent protection.

If the pH value is too high, side reactions will lead to incorrect results. With a too low pH value, titration will take too long. It is therefore essential to estimate of, or better verify, the pH value for a specific type of sample. Most pH electrodes contain an aqueous electrolyte which may give the illusion of an incorrect water contents of the sample.

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2.3 Working specifications 4.3.1 Titer determination

Method No. 1 Application Titer determination of KF titration agents Equipment TitroLine KF Titrator or TitroLine alpha

TM KF Titration Stand (TL KF scope of delivery) TZ 1770 Titration vessel (TL KF scope of delivery) TZ 1106 Double platinum electrode (TL KF scope of delivery) TZ 1721 Solid lock 5 ml one-way syringe with needle length approx. 60 mm plus needle protector 3 or 4-digit weighing-balance Beaker glass

Reagents Titration agents: Single- or two-component titration agents Pattern: Methanol, Composolver, or solvent depending on the titration agent Standard: Depending on the standard, please refer to table

Sample preparation Sample input ⇒ Through the septum using a syringe and needle

⇒ Using a solid lock Directly, by opening the plug Connection of an oven Introduction of gas

Description The “titer determination” method is selected, and the calculation factor is checked.Liquid standard: The standard is weighed in in the one-way syringe (water in a microliter syringe). The consumption to be expected should be approx. 5 ml. With reagent 5 mg water/ml this would be: Standard 10 mg water / ml: 2.500 g Standard 5 mg water / g: 5.000 g Tare the weighing-balance, transfer the sample through the septum in the titration vessel, then weigh the empty syringe again. Enter the weight on the titrator. Start titration.

Solid standard: Tare the weighing-balance. The standard (approx. 160 mg of sodium tartrate-hydrate) is weighed in the inner part of the solid lock using the weighing-balance. Carefully push the inner part of the solid lock into the outer part until the standard disappears completely in the lock and cannot fall off. The closed solid lock is then placed in the opening of the titration vessel, start conditioning. Upon completion of the conditioning process, push the inner part fully down so it can dissolve. Place the weighed-in quantity in the titrator, then start titration.

Calculation Liquid standard: Concentration titration agent [mg/ml] = weighed-in quantity [g] * standard [mg water/g] * factor 1 / ((consumption [ml] – blank value [ml]) * factor 2)

Water: Concentration titration agent [mg/ml] = weighed-in quantity [mg] ((consumption [ml] – blank value [ml]) * factor 2)

Sodium tartrate-hydrate: Concentration titration agent [mg/ml] = weighed-in quantity [g] * 1000 * 0.1566 ((consumption [ml] – blank value [ml]) * factor 2)

Parameter End value: 20 µA Switch-off time: 10 sec Potential: 100 mV

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4.3.2 Use of single-component reagents

Method No. 2 Application Titration with single-component reagents Equipment TitroLine KF Titrator or TitroLine alpha

TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode TZ 1721 Solid lock 5 ml one-way syringe with needle length approx. 60 mm plus needle protector 3 or better 4-digit weighing-balance Glass beaker

Reagents Titration reagent: Single-component reagent Pattern: Methanol, composolver or Combi solvent and mixtures

Sample preparation Feste Proben werden ggf. zerkleinert, flüssige Proben mit einer Spritze direkt auf-genommen, hochviskose Proben mit der Spritze ohne Nadel aufgezogen.

Sample input ⇒ Through the septum using a syringe and needle ⇒ Using a solid lock

Directly, by opening the plug Connection of an oven Introduction of gas

Description The „sample titration“method is selected, and the calculation factor is checked. Liquid and high-viscous standards: Der Probe wird in der Einwegspritze eingewogen. Die Waage wird tariert, die Probe durch das Septum in das Titrationsgefäß überführt und die leere Spritze zurückge-wogen. Das Gewicht wird am Titrator eingegeben. Die Titration wird gestartet.

Solid standard: Tare the weighing-balance. Die Probe wird im Innenteil der Feststoffschleuse aufder Waage eingewogen und die Einwaage notiert. Carefully push the inner part of the solid lock into the outer part until the standard disappears completely in the lock and cannot fall off. The closed solid lock is then placed in the opening of the titration vessel, start conditioning. Upon completion of the conditioning process, push the inner part fully down so it can dissolve. Place the weighed-in quantity in the titrator, then start titration.

Calculation % Water = (consumption [ml] – blank value [ml]) * 100 / (weighed-in quantity [g] * 1000)

Parameters End value: 20 µA End point delay: 10 sec Potential: 100 mV

Notice ⇒ Der Titer muss unter den gleichen Bedingungen bestimmt werden, unter denen die Probe titriert wird, z. B. das gleiche Lösungsmittelgemisch ⇒ Für unpolare Substanzen (Fette und Öle) kann dem Methanol zugesetzt werden: Chloroform (bis etwa 50 %), Petrolether oder Ligroin (bis etwa 40 %), langkettige Alkohole (bis etwa 50 %) ⇒ Für polare Substanzen (Zucker, Salze,..) kann Formamid (bis etwa 35 %) zu-gegeben werden. Höhere Formamidgehalte können zu einer veränderten Stöchio-metrie führen.

15

4.3.3 Use of two-comonent systems

Method No. 3 Application Titration with two-component systems Equipment TitroLine KF Titrator or TitroLine alpha

TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode TZ 1721 Solid lock 5 ml one-way syringe with needle length approx. 60 mm plus needle protector 3 or better 4-digit weighing-balance Glass beaker

Reagents Titration agent: two-component agent Pattern: Two-component agent ACHTUNG: Die Lösungsmittelkomponente enthält für die chemische Reaktion

notwendige Bestandteile. Deshalb nur vom Hersteller empfohlene Zusammen setzungen einsetzen!

Sample preparation Feste Proben werden ggf. zerkleinert, flüssige Proben mit einer Spritze direkt aufgenommen, hochviskose Proben mit der Spritze ohne Nadel aufgezogen.

Sample input ⇒ Through the septum using a syringe and needle ⇒ Using a solid lock

Directly, by opening the plug Connection of an oven Introduction of gas

Description Es wird die Methode „Probentitration“ ausgewählt und die Auswerteeinheit ausge-wählt. Liquid and high-viscous standards: Der Probe wird in der Einwegspritze eingewogen. Die Waage wird tariert, die Probe durch das Septum in das Titrationsgefäß überführt und die leere Spritze zurückgewogen. Das Gewicht wird am Titrator eingegeben. Die Titration wird ge-startet.

Solid standard: Die Waage wird tariert. Die Probe wird im Innenteil der Feststoffschleuse auf der Waage eingewogen und die Einwaage notiert. Carefully push the inner part of the solid lock into the outer part until the standard disappears completely in the lock and cannot fall off. The closed solid lock is then placed in the opening of the titration vessel, start conditioning. Upon completion of the conditioning process, push the inner part fully down so it can dissolve. Place the weighed-in quantity in the titrator, then start titration.

Calculation % Water = (sonsumption [ml] – blind value [ml])* 100 / (weighed-in quantity [g] * 1000)

Parameters End value: 20 µA Switch-off time:10 sec Potential: 100 mV

Notice • Der Titer muss unter den gleichen Bedingungen bestimmt werden, unter denen die Probe titriert wird, z.B. das gleiche Lösungsmittelgemisch

• Es sind Zusätze andere Lösungsmittel in geringem Maße möglich. • Die Titration ist sehr schnell. Die Probe sollte daher bei Beginn der

Titration schon möglichst vollständig gelöst sein. Bei Proben mit langsamer Wasserabgabe muss die Abschaltzeit verlängert werden.

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4.3.4 Working with liquid samples

Method No. 4

Application Titration with liquid samples

Equipment TitroLine KF Titrator or TitroLine alpha TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode TZ ???? Solid lock 5 ml one-way syringe with needle length approx. 60 mm plus needle protector 3 or 4-digit weighing-balance Beaker glass

Reagents Titriermittel: Ein- oder Zwei-Komponenten Titriermittel Vorlage: Methanol, Composolver or Solvent je nach Titriermittel

Sample preparation Die flüssige Proben mit einer Spritze direkt aufgenommen, hochviskose Proben mit der Spritze ohne Nadel aufgezogen.

Sample input ⇒ Through the septum using a syringe and needle Using a solid lock (solid standards)

⇒ Directly by openiung the plug (high-viscous standards, solid standards) Connection of an oven Introduction of gas

Description The „sample titration“ method is selected, and the calculation factor is checked. Liquid and high-viscous standards: Der Probe wird in der Einwegspritze mit Nadelschutz eingewogen. Die Waage wird tariert, die Probe nach Entfernen des Nadelschutzes durch das Septum in das Titrationsgefäß überführt und die leere Spritze zurückgewogen mit Nadel-schutz. Das Gewicht wird am Titrator eingegeben. Then start titration.


Parameters End value: 20 µA Switch-off time:10 sec Potential: 100 mV

Notice ⇒ Der Titer muss unter den gleichen Bedingungen bestimmt werden, unter de-nen die Probe titriert wird, z. B. das gleiche Lösungsmittelgemisch ⇒ Für unpolare Substanzen (Fette und Öle) kann dem Methanol beim Einko monentenreagenz zugesetzt werden: Chloroform (bis etwa 50%), Petrolether oder Ligroin (bis etwa 40 %), langkettige Alkohole (bis etwa 50 %) ⇒ Für polare Substanzen (Zucker, Salze,..) kann Formamid (bis etwa 35 %) zu-gegeben werden. Höhere Formamidgehalte können zu einer veränderten Stöchi-ometrie führen. ⇒ Beim Zweikomponentensystem kann in begrenztem Maße Lösungsvermittler zugefügt werden.

17

4.3.5 Working with solid samples and direct input

Method No. 5 Application Titration with single-component reagents Equipment TitroLine KF Titrator

TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode 3 or 4-digit weighing-balance

Reagents Titriermittel: Ein- oder Zwei-Komponenten Titriermittel Vorlage: Methanol, composolver or Solvent je nach Titriermittel

Sample preparation Feste Proben werden ggf. zerkleinert und in einem Wägeschiffchen oder Becherglas eingewogen und direkt in die Zelle überführt.

Sample input Through the septum using a syringe and needle (liquid standard) Using a solid lock (solid standard)

⇒ Directly, by opening the plug Connection of an oven Introduction of gas

Description Es wird die Methode „Probentitration“ gewählt und die Auswerteeinheit ausgewählt.Solid standard: Die Waage wird tariert. Die Probe wird in einem Wägeschiffchen oder Becherglas eingewogen. Das Konditionieren wird gestartet. Nach der Beendigung des Kondi-tionieren wird die Probe durch Öffnen des Stopfens direkt in die Titrationszellegegeben. Wenn Reste nicht in die Zelle überführt werden können, wird dieEinwaage wie bei flüssigen Proben durch Rückwägung ermittelt. Die Einwaage wird in den Titrator eingegeben und die Titration gestartet. In vielen Fällen wird in einer Wartezeit die Probe aufgelöst oder extrahiert, dann beginnt die Titration.


Parameters End value: 20 µA Switch-off time: 10 sec Potential: 100 mV

Notice ⇒ Der Titer muss unter den gleichen Bedingungen bestimmt werden, unter denen die Probe titriert wird, z. B. das gleiche Lösungsmittelgemisch. ⇒ Viele feste Proben brauchen eine gewisse Zeit, bis sie sich lösen oder das Wasser komplett abgeben. ⇒ Es empfiehlt sich, vorher einen Blindwert zu bestimmen und diesen automatisch zur Korrektur des Ergebnisses zu verwenden.

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4.3.6 Working with solid samples and solid lock

Method No. 6

Application Titration with solid samples and solid lock

Equipment TitroLine KF Titrator TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode TZ 1721 Solid lock 3 or 4-digt weighing balance Beaker glass

Reagents Titriermittel: Ein- oder Zwei-Komponenten Titriermittel Vorlage: Methanol, Composolver oder Solvent je nach Titriermittel

Sample preparation Feste Proben werden ggf. zerkleinert und in den inneren Teil der Feststoffschleu-se überführt. Es hat bis etwa ein Gramm darin Platz. Großvolumigere Proben müssen direkt in die Zelle überführt werden.

Sample input Through the septum using a syringe and needle (liquid standard) ⇒ Using a solid lock (solid standard)

Directly, by opening the plug (hochviskose Proben, solid standards) Connection of an oven Introduction of gas

Description Es wird die Methode „Probentitration“ ausgewählt und die Auswerteeinheit ausge-wählt.

Solid standard: Tare the weighing balance. The standard is weighed in the inner part of the solid lock using the weighing-balance. Carefully push the inner part of the solid lock into the outer part until the standard dissapears completey in the lock and cannot fall off. The closed solid lock is then placed in the opening of the titration vessel. Start conditioning. Upon completion of the conditioning pocess, push the inner part fully down so it can dissolve. Place the weighed-in quantity in the titrator, then start titration.

Calculation % Water = (consumption [ml] – blind value [ml]) * 100 / (weighed-in quantity [g] * 1000)


Notice ⇒ Der Titer muss unter den gleichen Bedingungen bestimmt werden, unter de-nen die Probe titriert wird, z. B. das gleiche Lösungsmittelgemisch ⇒ Die Arbeit mit der Feststoffschleuse kann mit einer höheren Drift verbunden sein (statt 3-5 µml/min bis zu 5-10 µml/min). ⇒ Es empfiehlt sich, vorher einen Blindwert zu bestimmen und diesen automa tisch zur Korrektur des Ergebnisses zu verwenden.

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4.3.7 Working with solid samples and homogenizer

Method No. 7 Application Titration with solid samples, die mit homogenizer zerkleinert werden müssenEquipment TitroLine KF Titrator

TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode 3 or 4-digit weighing balance Beaker glass Homogenisator e.g. CAT X 620/520 mit Tool T 10 Gewinderohr GL 18 mit NS Kern 19/26 (SCHOTT 24 841 71) Schraubkappenverschluss GL 18 (SCHOTT 29 227 06) Silikondichtung GL 18 with 9-11 mm I.D. (SCHOTT 29 235 10)


Sample preparation Feste Proben werden ggf. zerkleinert und direkt durch die Homogenisatoröffnung in die Titrierzelle gegeben.

Sample input Through the septum using a syringe and needle (liquid standard) Using a solid lock (solid standard) Directly by opening the plug (der Homogenisator wird an der Stativstange angeho-ben und nach Probenzugabe wieder in die Öffnung gesenkt). Connection of an oven Introduction of gas

Decription Es wird die Methode „Probentitration“ gewählt und die Auswerteeinheit ausgewählt. Solid standard: Tare the weighing-balance. Die Probe wird in einem Wägeschiffchen oder Becher-glas eingewogen. Das Konditionieren wird gestartet. Nach der Beendigung des Konditionieren wird die Probe durch Anheben des Homenisators direkt in die Titra-tionszelle gegeben. Wenn Reste nicht in die Zelle überführt werden können, wird die Einwaage wie bei flüssigen Proben durch Rückwägung ermittelt. Die Einwaage wird in den Titrator eingegeben und die Titration gestartet. In vielen Fällen wird in einer Wartezeit die Probe aufgelöst oder extrahiert, dann beginnt die Titration.



Notice ⇒ Der Titer muss unter den gleichen Bedingungen bestimmt werden, unter denen die Probe titriert wird, z. B. das gleiche Lösungsmittelgemisch ⇒ Es empfiehlt sich, vorher einen Blindwert zu bestimmen und diesen automatisch zur Korrektur des Ergebnisses zu verwenden.

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4.3.8 Working with raised temperature

Method No. 8 Application Titration single-component reagent Equipment TitroLine KF Titrator

TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode TZ 1721 Solid lock 5 ml one-way syringe with needle length approx. 60 mm plus needle protector 3 or 4-digit weighing balance Beaker glass Temperierbarer Magnetic Stirrer CAT ECM 6; Die Titrationszelle wird an der Stativstange des TM KF befestigt und

direkt daneben auf den Magnetrührer gestellt. Dimroth-Kühler NS 14/23 160 mm


Sample preparation Feste Proben werden ggf. zerkleinert, flüssige Proben mit einer Spritze direkt aufgenommen, hochviskose Proben mit der Spritze ohne Nadel aufgezogen.

Sample input ⇒ Through the septum using a syringe and needle (liquid standards) ⇒ Using a solid lock (solid standards) ⇒ Directly by opening the plug (hochviskose Proben, feste Proben)

Connection of an oven Introduction of gas

Description Es wird die Methode „Probentitration“ gewählt und die Auswerteeinheit ausgewählt. Temperatureinstellung: Die Temperatur wird langsam hochgeregelt, so dass 50 °C nicht überschritten wer-den. Wenn mit höheren Temeraturen gearbeitet werden soll, muss mit einem Rück-flusskühler gearbeitet werden.

Arbeiten mit Kühler: Der Kühler wird in die Öffnung NS 14 des Trockenröhrchens gesteckt. Das Trockenröhrchen wird auf den Kühler gesetzt. Der Kühler wird an Kühlwasser angeschlossen.

Flüssige und hochviskose Probe: Der Probe wird in der Einwegspritze eingewogen. Die Waage wird tariert, die Probe durch das Septum in das Titrationsgefäß überführt und die leere Spritze zurückge-wogen. Das Gewicht wird am Titrator eingegeben. Die Titration wird gestartet.

Solid standard: Die Waage wird tariert. Die Probe wird im Innenteil der Feststoffschleuse auf der Waage eingewogen und die Einwaage notiert. Das Innenteil der Feststoffschleuse wird vorsichtig in das äußere Teil geschoben, bis der Standard komplett in der Schleuse verschindet und nicht herausfallen kann. Die Feststoffschleuse wird ge-schlossen in die Öffnung des Titrationsgefäßes gegeben. Das Konditionieren wird gestartet. Nach der Beendigung des Konditionieren wird des innere Teil bis zum Anschlag heruntergeschoben, damit er sich auflösen kann. Die Einwaage wird in den Titrator eingegeben und die Titration gestartet.



Notice ⇒ Der Titer muss unter den gleichen Bedingungen bestimmt werden, unter denen die Probe titriert wird, z.B. das gleiche Lösungsmittelgemisch. ⇒ Es empfiehlt sich, vorher einen Blindwert zu bestimmen und diesen automatisch zur Korrektur des Ergebnisses zu verwenden.

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4.3.9 Working with external extraction Working specifications, calculation models, solvent mix to be prepared and dried before. Blank value to be taken into account.

Method No. 9 Application Titration with external extracton Equipment TitroLine KF Titrator

TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode 5 ml one-way syringe with needle length approx. 60 mm plus needle protector 3 or 4-digit weighing balance Beaker glass Extraktionsgefäß für externe Extraktion, z.B. Flaschen mit Septen


Sample preparation Die Probe wird genau gewogen in ein Gefäß mit Septum gegeben und eine (zum Beispiel durch Wiegen) exakt definierte Menge (z.B. 20 ml) möglichst trockenesLösungsmittel hinzugefügt. Der Restwassergehalt des Lösungsmittel muss als Blindwert separat bestimmt werden. Die Probe wird über längere Zeit in dieserFlasche belassen. Der Zeitraum kann 1 – 10 Stunden betragen. Er hängt vonWasserabgabe der Probe in dem gewählten Lösungsmittel ab.

Sample input ⇒ Through the septum using a syringe and needle (liquid standards) ⇒ Using a solid lock (solid standard) ⇒ Directly by opening the plug (hochviskose Proben, solid standard)

Connection of an oven Introduction of gas

Description Es wird die Methode „Probentitration“ gewählt und die Auswerteeinheit ausgewählt. Probenabmessung: Mit der Einwegspritze wird ein Teil der extrahierten Probe im Lösungsmittelentnommen und gewogen. Die Waage wird tariert, die Probe durch das Septum in das Titrationsgefäß überführt und die leere Spritze zurückgewogen. Der Anteil der Probe am Gesamtgewicht Probe und Lösungsmittel wird am Titrator eingegeben.

Example: 1.000 g Probe genau gewogen werden mit exakt 20 g Lösungsmittel extrahiert. Das Wasser der Probe befindet sich nach der Extraktion vollständig im Lösungsmittel. Es werden 10 g Lösungsmittel (jetzt mit dem Wasser) entnommen und in die Zelle überführt. Die Probeneinwaage [g] ist: Probenmenge [g] * Lösungsmittel in Titrierzelle [g] / Gesamtlösungsmittel [g] In unserem Beispiel wäre die Probenmenge 0,500 g! Der Blindwert ist in aller Regel niedrig und wird mit ca. 10 g Lösungsmittel be-stimmt. Then start tiration.

Calculation % Water = (consumption [ml] – blind value [ml])* 100 / (weighed-in quantity [g] * 1000)


Notice • Der Titer muss unter den gleichen Bedingungen bestimmt werden, unter denen die Probe titriert wird, z. B. das gleiche Lösungsmittelgemisch

• Es empfiehlt sich, vorher einen Blindwert zu bestimmen und diesen automatisch zur Korrektur des Ergebnisses zu verwenden. Die Menge für den Blindwert und die Probentitration müssen identisch sein.

22

4.3.10 Working with the oven

Method No. 10 Application Titration with the oven Equipment TitroLine KF Titrator

TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode 5 ml one-way syringe with needle len approx. 60 mmplus needle protector

Wägeschiffchen 3 or 4-digit weighing-balance Beaker glass TZ 1052 Drying oven TZ 1050 Accessories

Reagents Titriermittel: Ein- oder Zwei-Komponenten Titriermittel Vorlage: Methanol, Composolver oder Solvent je nach Titriermittel Trägergas (z.B. Stickstoff)

Sample preparation Feste Proben werden ggf. zerkleinert, flüssige Proben mit einer Spritze direkt aufge-nommen, hochviskose Proben mit der Spritze ohne Nadel aufgezogen.

Sample input ⇒ Mit Spritze und Nadel in das Schiffchen des Ofens (liquid standard) ⇒ Using a solid lock (solid standard) ⇒ Durch Öffnen des Stopfens direkt in das Schiffchen des Ofens (high-viscous standards, solid standards) ⇒ Connection of an oven ⇒ Introduction of gas

Description Der Ofen wird auf die erforderliche Temperatur aufgeheizt. Die Temperatur hängt von der Art der Probe ab. Es wird etwa 250 ml/min getrocknetes Gas (z.B. Stickstoff) durch den Ofen geleitet (die besten Erfahrungen liegen zwischen 150 – 500 ml/min). Im Titrationsgefäßkönnen noch gut die einzelnen aufsteigenden Luftblasen unterschieden werden. Wenn der Ofen aufgeheizt ist, wird der Gasstrom abgeschaltet und konditioniert. Nach dem Konditieren wird das Gas wieder eingeschaltet und der Blindwert wird über den gleichen Zeitraum bestimmt, den später die Probe im Ofen sein wird.

Für die Probentitration wird konditioniert wie vor. Die Probe wird eingewogen und in den Ofen auf das Schiffchen gegeben. Das Schiffchen wird mit der Handkurbel in den heißen Teil des Ofens geschoben. Die Probenmenge wird eingegeben und die Titration gestartet. Der Gasstrom wird auf die gleiche Menge eingestellt, wie beim Blindwert. Die Titration beginnt nach einer Wartezeit von üblicherweise 10 Minuten.

Calculation % Water = (consumption [ml] – blind value [ml]) * 100 / (weighed-in quantity [g] * 1000)

Parameters Waiting time: 10 minutes or 600 seconds End value: 20 µA Switch-off time: 10 sec Potential: 100 mV

Notice • Der Titer muss unter den gleichen Bedingungen bestimmt werden, unter denen die Probe titriert wird, z.B. das gleiche Lösungsmittelgemisch

• Der Blindwert hat bei dieser Methode einen großen Einfluss und muss unter den gleichen Bedingungen bestimmt werden, unter denen die Proben titriert werden.

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2.2.3.1 General form of working specifications

Method No. 11 Application Blind value

Titer determination Sample titration

Equipment TitroLine KF Titrator TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode TZ 1721 Solid lock 5 ml one-way syringe with needle length approx. 60 mm plus needle protector

Wägeschiffchen 3 or 4-digit weighing-balance Beaker glass TZ 1052 Drying oven TZ 1050 Accessories Further accessories

Reagents Titriermittel: Ein- oder Zwei-Komponenten Titriermittel Vorlage: Methanol, Composolver oder Solvent je nach Titriermittel Trägergas (z.B. Stickstoff) Standard 10 mg water / g or other standard Andere Reagenzien: Lösungsmittel

Sample preparation Direkte Eingabe der Probe in das Titrationsgefäß Aufnahme der Probe mit einer Spritze mit Kanüle Aufnahme der Probe mit einer Spritze Interne Extraktion durch Wartezeit vor der Titration External extraction Ausheizen mit dem Ofen

Sample input Mit Spritze und Nadel in das Schiffchen des Ofens (flüssige Proben) With solid lock (solid standards) Durch Öffnen des Stopfens direkt in das Schiffchen des Ofens (high-viscous

standards, solid standards) Connection of an oven Introduction of gas

Description Beschreibung der Vorgehens mit folgenden Kriterien: Blindwert wichtig Ermittlung und Begrenzung der Probenmenge Art und Menge Lösungsmittel

Calculation Probe: % Water = (consumption [ml] – blind value [ml]) * 100 / (weighed-in quantity [g] * 1000)

Liquid standard: Concentration titration agent [mg/ml] = weighed-in quantity [g] * Standard [mg water/g] * factor 1 / ((consumption [ml] – blind value [ml]) * factor 2

Water: Concentration titratin agent [mg/ml] = weighed-in quantity [mg] ((consumption [ml] – blind value [ml]) * factor 2)

Sodium tartrate-hydrate: Concentration titration agent [mg/ml] = weighed-in quantity [g] * 1000 * 0,1566 ((consumption [ml] – blind value [ml]) * factor 2)

24

Parameters Waiting time: ________ min

End value: ________ µA Switch-off time: ________ sec Potential: ________ mV

Notice Der Titer muss unter den gleichen Bedingungen bestimmt werden, unter denen die Probe titriert wird, z.B. das gleiche Lösungsmittelgemisch.

Der Blindwert hat bei dieser Methode einen großen Einfluss und muss unter den gleichen Bedingungen bestimmt werden, unter denen die Proben titriert werden.

Weitere Hinweise Warn- und Sicherheitshinweise

4.3.11 Inspection of the titration system Regulations concerning titration and the standard enclosed with the delivery. Desired results, error descriptions.

Method No. 12 a Application Inspection of the titration system Part I: Titerstellung Equipment TitroLine KF Titrator

TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode 5 ml one-way syringe with needle length approx. 60 mm plus needle protector 3 or 4-digti weighing-balance Beaker glass

Reagents Titration agent: Two-component titration agents Pattern: Solvent according to titration agent Standard 10 mg water / g or other standard

Sample preparation

Die Spitze der Ampulle mit dem Standard wird aufgebrochen. Aufnahme des Standards (ca. 2 ml auf 3 oder 4 Stellen genau) mit einer Spritze mit Kanüle. Der Nadel-Schutz wird aufgezogen und die Spritze mit der Nadel nach oben in ein Becherglas auf die Waage ge-stellt. Die Waage wird tariert.

Sample input Der Nadelschutz wird abgenommen und die Probe langsam ohne Eintauchen durch das Septum in das Titrationsgefäß gespritzt. Den Nadelschutz wieder aufziehen und die Spritze zurückwiegen. Das an der Waage angezeigte Gewicht wird am Titrator eingegeben.

Description Es wird aus der Lösungsmittelflasche so viel Solvent in das Titrationsgefäß gepumpt, bis die Stifte der Doppelplatinelektrode vollständig eintauchen. Die Methode Titerstellung wird gewählt und gestartet. Der Titrator konditioniert. Wenn die Zelle trocken ist, wird das Konditionieren beendet. Der Nadelschutz wird abgenommen und die Probe langsam ohne Eintauchen durch das Septum in das Titrationsgefäß gespritzt. Der Nadelschutz wird wieder aufgezogen und die Spritze zurückgewogen. Das an der Waage angezeigte Gewicht wird am Titrator eingege-ben. Die Titration wird gestartet. Nach Beenden der Titration wird das Ergebnis angezeigt bzw. ausgedruckt. Diese Titration wird drei mal wiederholt.

Die Ergebnisse sollten den Titer der Titrierlösung angeben: Type reagent [mg water/ml] rel. standard deviation [%] 1 0.8 .. 1.2 < 2 2 1.5 .. 2.5 < 1 2.5 2.0 .. 3.5 < 1 5 4.0 .. 5.5 < 0.5

Calculation Liquid standard: Concentration titration agent [mg/ml] = weighed-in quantity [g] * 10,00 ((consumption [ml] – 0,0) * 1,00

Parameters Waiting time: 5 min; End value: 20 µA Switch-off time: 10 sec; Potential: 100 mV

Notice Warning and safety information

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Method No. 12 b Application Überprüfung des Titrationssystems Teil II: Testtitration Equipment TitroLine KF Titrator

TM KF Titration Stand TZ 1770 Titration vessel TZ 1106 Double platinum electrode 5 ml one-way syringe with needle length approx. 60 mm plus needle protector 3 or 4-digti weighing-balance Beaker glass

Reagents Titration agent: Two-component titration agents Pattern: Solvent according to titration agent Standard 10 mg water / g or other standard

Sample preparation Die Spitze der Ampulle mit dem Standard wird aufgebrochen. Aufnahme desStandards (ca. 2 ml auf 3 oder 4 Stellen genau) mit einer Spritze mit Kanüle. Der Nadel-Schutz wird aufgezogen und die Spritze mit der Nadel nach oben in einBecherglas auf die Waage gestellt. Die Waage wird tariert.

Sample input Der Nadelschutz wird abgenommen und die Probe langsam ohne Eintauchen durch das Septum in das Titrationsgefäß gespritzt. Der Nadelschutz wird wieder aufgezogen und die Spritze zurückgewogen. Das an der Waage angezeigte Ge-wicht wird am Titrator eingegeben.

Description Es wird aus der Lösungsmittelflasche so viel Solvent in das Titrationsgefäßgepumpt, bis die Stifte der Doppelplatinelektrode vollständig eintauchen. Die Methode Probe wird gewählt und gestartet. Der Titrator konditioniert. Wenn die Zelle trocken ist, wird das Konditionieren beendet. Die Nadelschutz wird abgenommen und die Probe langsam ohne Eintauchen durch das Septum in das Titrationsgefäß gespritzt. Der Nadelschutz wird wieder aufgezo-gen und die Spritze zurückgewogen. Das an der Waage angezeigte Gewicht wird am Titrator eingegeben. Die Titration wird gestartet. Nach Beenden der Titration wird das Ergebnis angezeigt bzw. ausgedruckt. Diese Titration wird dreimal wiederholt. Die Ergebnisse sollten den Wassergehalt des Standards in % Wasser angeben. Der Wassergehalt des Standards ist 1,00 %. Die relative Standardabweichung sollte < 0,5 % sein.

Calculation Probe: % Water = (consumption [ml] – 0.00) * 100 / (weighed-in quantity [g] * 1000)

Parameters Waiting time: 5 min End value: 20 µA Switch-off time: 10 sec Potential: 100 mV

Notice Warning and safety information

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2.4 Error and their consequences 4.4.1 The titration takes too long If the titration takes too long (> 5 minutes), something is not in order in most cases. The causes may be of a quite trivial nature. The following list shows causes for an excessive duration of titration and provides information on how to detect and eliminate the individual causes.

Wrong solvent In particular with the two-component reagents, it happens from time to time that, for instance, methanol

alone is used instead of a correct solvent including the required reaction partners. KF titration cannot take place. Cell open or leaking

The drift is extraordinarily high. If its general value is around 4 µl/min, and suddenly it is in the range of 10 µl/min, this is a frequent cause of error. Titration agent used up

Trivial, yet not uncommon. The dark brown bottles and the light-protected units make it difficult to see whether there is enough reagent contained in the bottle or in the unit. Side reactions

In addition to the actual KF reaction, a side reaction is taking place which is also consuming titration agent. Towards the end, the drift remains constant on a certain value, for instance at 20 µl/min. Chemicals too old

A “best before” date which should not be exceeded is printed on most reagents. If their use cannot be avoided, the titration should be observed closely. No more drying effect of desiccant The molecular sieve should be re-dried on a regular basis (> = 250 °C over more than three hours). Used molecular sieve makes itself noticeable by an above-normal drift (e.g. 6 instead of 4).

4.4.2 The titration solution turns brown If the titration solution turns brown, one of the following problems is present as a rule:

Overtitration The titration reaches the end point too early, and therefore overtitration occurs. In order to determine

the overtitration quantity, use the syringe to introduce drops of standard through the septum until a discoloration takes place. Count the drops, then determine the water contents for the drop number separately. Microtip has come off

The titration reaches the end point too early, and therefore overtitration occurs. In order to determine the overtitration quantity, use the syringe to introduce drops of standard through the septum until a discoloration takes place. Count the drops, then determine the water contents for the drop number separately. No water in sample

If the titration begins with no water being contained in the sample, (insignificant) overtitration will occur as a matter of course.

4.4.3 Detected water contents is too low There are many causes for incorrect titration results. Below are just a few examples of causes of errors.

Wrong titer The titer was not determined correctly or has changed.

Wrong reagent The new reagent has a different factor, or it is a different titration agent.

Sample not dissolved (or only partially) If the sample is not fully dissolved, then only a part of the water can be determined.

Sample not comminuted If samples are not disintegrated the water in the sample may often not be released to a sufficient degree.

Titration conditions are not ideal Under non-optimum titration conditions (polarity, solvent, pH value, temperature, ...), it may e.g. happen

that too little water is found in the sample.

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4.4.4 Detected water contents is too high Side reactions

A side reaction will always lead to an excessive value (please refer to the side reactions chapter). Wrong titer

The titer was not determined correctly, or it has changed. Wrong reagent

The titer was not determined correctly, or it has changed. Sample not homogenous

A part of the sample with a higher water contents may have been taken. Incorrect formula

The results may be incorrect owing to wrong blank values, titer. Is “sample titration” actually the current method? An incorrect result unit was selected.

4.4.5 Brown titration solution is leaking Leakage

After cleaning a unit it may happen from time to time that the hoses are not tightened firmly enough. A thread may have been damaged as a result of an excessive tightening of the hoses. Microtip off

The micro titration tip with the valve is only plugged on the hose. It may have been pushed out, e.g. by clogging. The risk of clogging is particularly high after longer periods without operation. Overpressure or vacuum within the system

If the openings in the titration vessel are clogged, a vacuum may build up in the titration vessel during the evacuation process. Likewise, an overpressure may occur during the dosage of the solvent or the titration agent.

4.4.6 Titration proceed fast and without stopping With two-component system: no solvent

With two-component reagents the solvent has to contain the SO2, base, and alcohol components, otherwise the KF reaction cannot take place. Please make sure that the matching components are being used. Excessive sample quantity

The sample contains so much water that the consumption is too high. The titration should be repeated with a smaller sample quantity after sucking the sample off. Excessive water contents

The sample contains so much water that the consumption is too high. The titration should be repeated with a smaller sample quantity after sucking the sample off. Contaminated solvents

The solvents contain so much water that the conditioning process consumes too much reagent and lasts too long. The solvents should be pre-dried. This also improves their water extraction properties.

4.4.7 Wrong output of the result Incorrect formula

An incorrect output unit was selected. Wrong method

Instead of the sample titration mode, titration was performed in the blank value or titer determination mode.

2.5 Validation of the KF titration The sounding of the term might imply truth. This would mean that “validation” would be supposed to ensure the veracity of an analysis result. However, Latin “validere” means “to correspond”, and this leads to the logic, official definition, DIN EN ISO 8402: “Confirmation on the basis of an investigation and by the provision of an objective proof of the fact that the special requirements imposed on a particular, intended use are met". Proof: provable information based on facts gathered by way of observation, measurement, a test, or in a similar form.

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4.5.1 Validation scheme and evaluation of general features The validation of a method requires a series of validation features which are identical for all methods. The individual items, however, are not of the same importance in each case. So it is, for instance, that the detection limit may certainly be particularly significant with regard to a method of trace analytics, whereas it is most likely to be irrelevant with regard to the contents determination in the high % range. In the following table, the validation features are evaluated including comments. Validation feature Importance Significance for titration Accuracy ++ the strong point of titration

Correctness ++ to be evidenced for each method

Traceability + as a rule, no sample preparation is necessary

Linearity + titration is a method with a high degree of linearity. The concentration range being used should have been verified.

Selectivity o usually of no importance Robustness ++ importance for the applicability to other methods Detection limit o usually omitted Determination limit o The range in which samples occur is defined and checked. As

a rule, however, the sample is adapted to achieve an uniform consumption.

Titration analysis methods Chemical reaction Reagent and dosage Indication

• Applicability Titer stability of the titration agent • Sensor functions according to specifications• Stoichiometry • Accurate dosability with accurate

volumes of the burette • Sensor is suitable for the indication of the

chemical transformation (selectivity, sensitivity)

• Reaction speed • Accurately known composition and contents of the reagent

• End of the chemical reaction

• Side reactions • Equivalent transformation can be read off or calculated from the curve

Chemical reaction Reagent and dosage Indication Reagent • Research and

publication • Ensures composition

Manufact. • Patents • Ensures durability Device • Experience • Ensures accurate dosing • Ensures indication function

• Applications • Declaration of conformity • Declaration of conformity Manufactu

rer • Manufacturer’s test certificate • Manufacturer’s test certificate

User • Validation • Titer determination • Curve analysis • Inspection of testing means • Inspection of testing means

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4.5.2 Inspection of testing means The manufacturer of a titration device warrants the proper functioning of his device. He verifies this, for instance, on the bases of the criteria contained in the appropriate tables (table 4 to 8). The user can adopt these features for his own testing-means inspection or make a selection which he considers useful for his own purposes. Table 4: Visual inspection Display Check segments: completeness, brightness, uniformity; check special characters Plug connections

Corrosion, solidity, bending, completeness, damage to the plug casings

Switches + pots Corrosion, smooth running, latching and end positions, mechanical stability, inscriptions

Casing Damage, impaired function Cylinder, piston Damage, wear and tear, dull glass, glass surfaces (interior and exterior) Piston rod Corrosion, damage Seals Liquid leakage, cracks, deformation Hoses Bends, damage, connection / threading, liquid leakage, air intake Internal structure General condition Printed boards Damage, in particular corrosion of the printed circuits, the components, the soldered

points, the plugs Functioning - mechanical system

Corrosion of and damage to the driving system, especially the spindle, play of the mechanical system

Table 5: Interfaces RS-232-C Functional check: Transmission of data to a test PC using terminal program others Practical functional check, e.g. SGH interface with connected SGH device Recorder output Measurement of 3 voltages, distributed across the range Controller input Practical functional check with the corresponding device Stirrer connection Practical functional check with connected stirrer Centronics Connect printer, transmit 5 values

Table 6: Electronics Measurement amplifier Inspection and readjustment according to alignment

instructions Controlling behaviour Visual inspection of the safety-relevant connections Electrical safety Measurement based on standards

Table 7: Dialogue system Keyboard function Menu scrolling, check of the function keys Parameter input Menu scrolling with a stop at 5 positions previously

determined at random. At these positions: Input of meaningful parameters. Check whether the values/characters displayed correspond to those input.

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Table 8: Additionally with QA inspections Certificate A quality certificate according to DIN 55350-18-4.2.2 is issued. This document can be

used in quality management systems according to DIN EN ISO 9000 ff. The certificate must only be issued by persons being nominated by the management and the quality management department.

Spindle travel To be measured in three points using an altimeter: 10 %, 50 %, 100 %, variance comparison

Spindle force Measurement of the maximum in a force-sensing device pH/mV ranges Variance comparison of the measurement deviation in 3 points each Temperature range

as pH/mV range

Dead-Stop range as pH/mV range Volume according DIN

Weighing with water according to DIN 12 650, Part 5, at 10 %, 50 %, 100 %, variance comparison

With regard to titration, the accurate dosage of the reagent is unquestionably the most important point. This is checked according to DIN 12650, Part 6. In the course of three dosing processes with approx. 10 %, 50 %, and 100 %, each value must not deviate by more than 0.3 % (or as per manufacturer’s specification) from the desired value, referred to the total volume of the cylinder of the burette. The new ISO 8655 (under preparation) requires 10 identical volumes each for nominal volume, 50 % nominal volume and the smallest selectable volume or 10 % of the nominal volume. The correctness of the volume with a 10 ml burette has to be ± 0.20 %, the precision has to be ± 0.10 per cent of the command volume The difference is found in the detail: whereas none of the single values must drop out according to the DIN, the news ISO makes weighing across a Gauss curve in which a individual value actually may be a "maverick". Considering that most of the motor piston burettes do not have to be calibrated, a volumetric inspection according to these norms is only seldom required. As a matter of experience, visual inspections at shorter intervals make sense. The more comprehensive volumetric inspection should be performed once per year or at shorter intervals if the device is subject to great load or if a deviation has been detected. A practice-oriented alternative (i.e. not according to any normative regulation) consists in a titer determination using a standard or a titrimetic standard in which different titration volumes are used. In this process the volumes are selected in such a way that the same quantity range as with the samples is recorded and, at the same time, different positions of the piston burette are present. In this way the electronics and many other items including the sensor are inspected automatically as well. The individual elements have a different influence on the different types of titration. For this reason, validation is discussed at this point on the basis of two examples. If specific particularities of the testing-means supervision are of any significant importance, a special reference will be made.

4.5.3 Tests to be made Test list including example:

Procee-ding

Elements What has to be done

Precon-ditions

Reactions A sample is titrated, the titration curve is analysed. Chapter XX shows the major features of a Karl Fischer titration curve. If the expected contents is smaller or greater than the first result, one has to reckon with a side reaction.

Reagent and dosing

A multiple determination (e.g. 10-fold) is performed using a standard, a titrimetric standard (di-sodium-tartrate dihydrate), or water (with microliter syringe, weigh if necessary). If different quantities are being used, which cover different burette volumes as well, this means that the proper functioning of the titrator is largely ensured. An additional testing-means supervision is only required if problems occur or if a basic inspection of the titrator is to be performed.

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Procee-ding

Elements What has to be done

Precon-ditions

Tightness of the titration vessel

The titration vessel has to be tight since the air contains a considerable amount of humidity. This is indicated by the drift. The drift should be less than 5 µg of water per minute. The drift will be greater if the oven is being used. The drift can be read off directly on the device, or it is easily obtainable by waiting for one hour after conditioning (drying of the solvent), followed by a start of a titration. The drift is calculated as follows: Drift [ µg/min] = consumption [ml] * titer [mg water/ml] * 1000 / 60 [min]

Indication The proper functioning of the indication can by be established easily: • Remove the double platinum electrode from the titration vessel • Start titration: no current is flowing, or no voltage is being indicated • Use a metal office clip to short-circuit the two platinum pins: a current is flowing, and titration will disrupt after the switch-off time. If this test is functioning, the indication system is working properly.

Validation Accuracy Multiple determination of a sample (e.g. 10-fold), determination of mean value and standard deviation

Correct-ness

• In the course of each determination, a defined quantity of water (or standard) is added several times to the sample. This quantity must be retraced completely. Mean value and standard deviations of the individual retraced quantities are noted. Less water is indicative of an incomplete transformation. A higher water contents indicates a drift or side reactions..

• The tests for linearity inspection are analysed. The straight line must show a slope (if the command consumption is recorded versus the actual consumption) of approx. 1.00. The straight line must lead through the zero point. The correlation coefficient should be close to 1.00. Deviations indicate a drift, side reactions, or incomplete transformations.

• Comparison to the standard the water contents and properties of which are known and which behaves identically to the sample. The standard has to be certified.

Retracing • In the course of each determination, a defined quantity of water (or standard) is added several times to the sample. This quantity must be retraced completely. Mean value and standard deviations of the individual retraced quantities are noted.

• Other samples with a known contents are added to the sample with a known contents. This sample quantity must be the retraced completely.

Linearity A number of samples with an increasing contents is titrated. In this process, for instance, 10 titrations are performed for each contents. The smallest and the greatest water contents should correspond to the practical requirements. The straight line must show a slope (if the command consumption is recorded versus the actual consumption) of approx. 1.00. The straight line must lead through the zero point. The correlation coefficient should be close to 1.00. Mean value and standard deviation of the individual titrations are calculated.

Selectivity Karl Fischer titration is selective for water. The method is tested for almost all types of samples. Side reactions have to be excluded (correctness, linearity, retracing).

Robust- ness

• Robustness may be determined in the form of an inter-laboratory test. • All the relevant paramters of Karl Fischer titration are varied: Electrode, solvent quantities, temperature, steering speed, titration paramters, titration device

Detection limit

The detection limit is no criterion in contents determination. It can be defined similar to the determination limit.

Determination limit

The determination limits result from linearity inspection. The smallest and greatest sample volumes which are located inside the linear range and meet the required standard deviation are defined as determination limits.

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2.6 KF titration and normative documents KF titration is contained in numerous normative documents. The following table will give you an overview of these standards.

Document number Title BS EN ISO 10101-1 NATURAL GAS – DETERMINATION OF WATER BY THE KARL FISCHER

METHOD – PART 1. INTRODUCTION BS EN ISO 10101-2 NATURAL GAS – DETERMINATION OF WATER BY KARL FISCHER

METHOD – PART 2. TITRATION PROCEDURE BS EN ISO 10101-3 NATURAL GASES – DETERMINATION OF WATER BY THE KARL FISCHER

METHOD PART 3. COULOMETRIC PROCEDURE DIN 10252 ANALYSIS OF TOBACCO AND TOBACCO PRODUCTS; DETERMINATION

OF WATER CONTENT; KARL FISCHER METHOD DIN 53715 DETERMINATION OF WATER CONTENT OF PLASTICS BY THE KARL

FISCHER METHOD DIN 53979 TEST OF AIDS FOR DRY-CLEANING; DETERMINATION OF THE WATER

CONTENT ACCORDING TO THE METHOD OF KARL FISCHER DIN EN ISO 10101-1 NATURAL GAS – DETERMINATION OF WATER BY THE KARL FISCHER

METHOD – PART 1. INTRODUCTION DIN EN ISO 10101-2 NATURAL GAS – DETERMINATION OF WATER BYTHE KARL FISCHER

METHOD – PART 2. TITRATION PROCEDURE DIN EN ISO 10101-3 NATURAL GAS – DETERMINATION OF WATER BY KARL FISCHER

METHOD – PART 3. COULOMETRIC PROCEDURE DS PD 3201 DETERMINATION OF WATER BY THE KARL FISCHER METHOD.

DETERMINATION OF WATER IN KETONES EN 60814 (BS) INSULATING LIQUIDS – OIL-IMPREGNATED PAPER AND PRESSBOARD –

DETERMINATION OF WATER BY AUTOMATIC COULOMETRIC KARL FISCHER TITRATION

IEC 60814 DETERMINATION OF WATER IN INSULATING LIQUIDS BY AUTOMATIC COULOMETRIC KARL FISCHER TITRATION

IP 356 WATER IN CRUDE OILS BY VOLUMETRIC KARL FISCHER TITRATION ISO 760 DETERMINTN.WATER-KARL FISHER METHOD (GENERAL METHOD) ISO 10101-1 NATURAL GAS – DETERMINATION OF WATER BY THE KARL FISCHER

METHOD – PART 1: INTRODUCTION ISO 10101-1 FRENCH NATURAL GAS – DETERMINATION OF WATER BY THE KARL FISCHER

METHOD – PART 1: INTRODUCTION ISO 10101-2 NATURAL GAS – DETERMINATION OF WATER BY THE KARL FISCHER

METHOD – PART 2: TITRATION PROCEDURE ISO 10101-2 FRENCH NATURAL GAS – DETERMINATION OF WATER BY THE KARL FISCHER

METHOD – PART 2: TITRATION PROCEDURE ISO 10101-3 NATURAL GAS – DETERMINATION OF WATER BY THE KARL FISCHER

METHOD – PART 3: COULOMETRIC PROCEDURE ISO 10101-3 FRENCH NATURAL GAS – DETERMINATION OF WATER BY THE KARL FISCHER

METHOD – PART 3: COULOMETRIC PROCEDURE ISO 10336 CRUDE PETROLEUM – DETERMINATION OF WATER – POTENTIOMETRIC

KARL FISCHER TITRATION METHOD ISO 10336 FRENCH CRUDE PETROLEUM – DETERMINATION OF WATER – POTENTIOMETRIC

KARL FISCHER TITRATION METHOD ISO 10337 CRUDE PETROLEUM – DETERMINATION OF WATER – COULOMETRIC

KARL FISCHER TITRATION METHOD ISO 10337 FRENCH CRUDE PETROLEUM – DETERMINATION OF WATER – COULOMETRIC

KARL FISCHER TITRATION METHOD ISO 10362-2 FRENCH CIGARETTES – DETERMINATION OF WATER IN SMOKE CONDENSATES –

PART 2: KARL FISCHER METHOD ISO 11021 ESSENTIAL OIL – DETERMINATION OF WATER CONTENT – KARL

FISCHER METHOD ANSI C59.53 WATER IN INSULATING LIQUIDS (KARL FISCHER METHOD)

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Document number Title API MPMS C10 S7 *E MEASUREMENT STANDARDS CHAPTER 10: SEDIMENT AND WATER

SECTION 7: STANDARD TEST METHOD FOR WATER IN CRUDE OILS BY KARL FISCHER TITRATION (VOLUMETRIC)

ASTM D 1123 TEST METHOD FOR WATER IN ENGINE COOLANT CONCENTRATE BY THE KARL FISCHER REAGENT METHOD

ASTM D 1364 STANDARD TEST METHOD FOR WATER IN VOLATILE SOLVENTS (KARL FISCHER REAGENT TITRATION METHOD)

ASTM D 1533 STANDARD TEST METHODS FOR WATER IN INSULATING LIQUIDS (KARL FISCHER REACTION METHOD)

ASTM D 1744 TEST METHOD FOR DETERMINATION OF WATER IN LIQUID PETROLEUM PRODUCTS BY KARL FISCHER REAGENT

ASTM D 4017 STANDARD TEST METHOD FOR WATER IN PAINTS AND PAINT MATERIALS BY KARL FISCHER METHOD

ASTM D 4377 WATER IN CRUDE OILS BY POTENTIOMETRIC KARL FISCHER TITRATION ASTM D 4928 WATER IN CRUDE OILS BY COULOMETRIC KARL FISCHER TITRATION ASTM D 5530 TEST METHOD FOR TOTAL MOISTURE OF HAZARDOUS WASTE FUEL BY

KARL FISCHER TITRIMETRY ASTM E 203 TEST METHOD FOR WATER USING VOLUMETRIC KARL FISCHER

TITRATION ASTM E 700 WATER IN GASES USING KARL FISCHER REAGENT ASTM F 1214 WATER SOLUBILITY IN LIQUID PETROLEUM BY KARL FISCHER BS 2511 METHODS FOR THE DETERMINATION OF WATER (KARL FISCHER

METHOD) BS 3156 S11.3 SS11.3.1

ANALYSIS OF FUEL GASES - PART 11. METHODS FOR NON-MANUFACTURED GASES - SECTION 11.3 DETERMINATION OF WATER IN NATURAL GAS BY THE KARL FISCHER METHOD - SUBSECTION 11.3.1 INTRODUCTION

BS 3156 S11.3 SS11.3.2

ANALYSIS OF FUEL GASES - PART 11. METHODS FOR NON-MANUFACTURED GASES - SECTION 11.3 DETERMINATION OF WATER IN NATURAL GAS BY THE KARL FISCHER METHOD - SUBSECTION 11.3.2 TITRATION METHOD

BS 3156 S11.3 SS11.3.3

ANALYSIS OF FUEL GASES - PART 11. METHODS FOR NON-MANUFACTURED GASES - SECTION 11.3 DETERMINATION OF WATER IN NATURAL GAS BY THE KARL FISCHER METHOD - SUBSECTION 11.3.3 COULOMETRIC METHOD

BS 4993 P5 METHODS OF TEST FOR ALUMINIUM FLUORIDE FOR INDUSTRIAL USE - DETERMINATION OF MOISTURE CONTENT (KARL FISCHER METHOD)

BS 5202 P15 METHODS FOR CHEMICAL ANALYSIS OF TOBACCO AND TOBACCO PRODUCTS - PART 15. DETERMINATION OF WATER IN SMOKE CONDENSATE OF CIGARETTES (KARL FISCHER METHOD)

BS 5202 P19 METHODS FOR CHEMICAL ANALYSIS OF TOBACCO AND TOBACCO PRODUCTS - PART 19. DETERMINATION OF WATER CONTENT (KARL FISCHER METHOD)

BS 5711 P8 DETERMINATION OF WATER CONTENT: KARL FISCHER METHOD BS 5752 P13 METHODS OF TEST FOR COFFEE AND COFFEE PRODUCTS - PART 13.

ROASTED GROUND COFFEE: DETERMINATION OF MOISTURE CONTENT [KARL FISCHER METHOD (REFERENCE METHOD)]

BS 6725 METHOD FOR DETERMINATION OF WATER IN LIQUID DIELECTRICS BY AUTOMATIC COULOMETRIC KARL FISCHER TITRATION

BS 684 P2 S2.1 METHODS OF ANALYSIS OF FATS AND FATTY OILS - PART 2: OTHER METHODS - SECTION 2.1: DETERMINATION OF WATER BY THE KARL FISCHER METHOD

ISO 11021 FRENCH ESSENTIAL OIL - DETERMINATION OF WATER CONTENT - KARL FISCHER METHOD

ISO 11817 ROASTED GROUND COFFEE - DETERMINATION OF MOISTURE CONTENT - KARL FISCHER METHODS (REFERENCE METHOD)

ISO 11817 FRENCH ROASTED GROUND COFFEE - DETERMINATION OF MOISTURE CONTENT - KARL FISCHER METHODS (REFERENCE METHOD)

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Document number Title ISO 4317 SURFACE-ACTIVE AGENTS AND DETERGENTS - DETERMINATION OF

WATER CONTENT - KARL FISCHER METHOD ISO 6488-1 TOBACCO - DETERMINATION OF WATER CONTENT - PART 1:

KARL FISCHER METHOD ISO 6488-1 FRENCH TOBACCO - DETERMINATION OF WATER CONTENT - PART 1:

KARL FISCHER METHOD ISO 8534 ANIMAL AND VEGETABLE FATS AND OILS - DETERMINATION OF WATER

CONTENT - KARL FISCHER METHOD ISO 8534 FRENCH ANIMAL AND VEGETABLE FATS AND OILS - DETERMINATION OF WATER

CONTENT - KARL FISCHER METHOD JIS K0113 GENERAL RULES FOR METHODS OF POTENTIOMETRIC,

AMPEROMETRIC COULOMETRIC, AND KARL-FISCHER TITRATIONS On the Internet, these normative documents or standards can be investigated and also ordered as titles or abstracts. The following addresses are intended to give you a starting point for your own excursion to the Internet:

ASTM http://www.astm.org Information Services GmbH http://www.global.ihs.com DIN-Normen http://www.din-normen.de VDE http://www.vde-verlag.de Technischer Fachbuch-Vertrieb http://www.tfv.ch

Further working specifications are contained in the Phamakopoeen (Ph. Eur. II; DAB 96, USP XXI).

2.7 KF titration and quality assurance As a rule, KF titration is used within the framework of quality assurance. Many aspects have already been mentioned in the validation section, such as the testing-means supervision. In order to enable the account for the current trends, it is not intended to list the features of all different quality systems. We rather include some important organisations including their Internet addresses.

Some features, however, should be noted here: ISO 9000: A testing-means supervision made ensure the eligibility for use of a KF titrator. In the preceding chapter as well as in the annex you will find some practical information. The attributality to a national or other standard is important. KF titration offers some certified standards. The scope of delivery of the TitroLine KF Titrator contains standards of this type. The manufacturer of the reagents will offer you detailed information in this context.

GLP/GMP This is focused on the contents and form of the documentation regarding the use of the TitroLine KF Titrator. The comprehensibility of the result is the most important requirement in this context.

Validation: Please refer to chapter XX

For the GLP and GMP range you will find a number of good tips on the Internet compiled by the DGGF association. DGGF (Deutsche Gesellschaft für Gute Forschungspraxis) http://www.dggf.de BARQA (British Association for Research Quality Assurance) http://www.barqa.com BIRA (British Institute of Regulatory Affairs) http://www.bira.org.uk

DIA (Drug Information Association) http://www.diahome.org ESRA (European Society of Regulatory Affairs), viele Links zu internationalen Behörden http://www.esra.org ISQA (International Society of Quality Assurance) http://www.quality.org/isqa.info.txt

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Almost all industrial association meanwhile have set up their own homepages. As a rule, you will find there information on the industry being served as well as on the economic importance plus links to the member companies.

International

ICH (International Conference on Harmonisation)

http://www.ifpma.org/ich1.html

Die Homepage der international abgestimmten Arzneimittelprüfrichtlinien

Deutschland

BAH (Bundesfachverband der Arzneimittel-Hersteller, Bonn)

http://www.bah-bonn.de

BPI (Bundesverband der Pharmazeutische Industrie, Frankfurt)

http://www.bpi.de

VCI (Verband der chemischen Industrie, Frankfurt)

http://www.chemische-industrie.de

EU (European Union) http://europa.eu.int/eur-lex The wording of all major laws of the European Union can be obtained here. You will get free access to publications of the gazette of the EU from the past 20 days as well as to the European Treaties, consolidated versions of the currently applicable EU law, and judgements of the European Court, and this in all official languages of the EU. They are updated on a daily basis.

OECD (Organisation for Economic Co-Operation and Development, Paris, Frankreich) http://www.oecd.org/ehs A brief English text on the OECD activities in the range of GLP as well as the complete English wording of the new edition of the "OECD Principles of GLP" and the consent documents can be found at http://www.oecd.org/ehs/glp.htm

US-FDA (U.S. Food & Drug Administration) http://www.fda.gov/fdahomepage.html

Food and Drug Administration Center for Drugs and Biologics Office of Drug Research and Review (HFN-100) 5600 Fishers Lane Rockville, Maryland 20857 (301-443-4330)

D-BgVV (Bundesinstitut für gesundheitlichen Verbraucherschutz und Veterinärmedizin, Berlin) http://www.bgvv.de Die GLP-Bundesstelle (z.Zt. ohne eigene Homepage) ist Teil des Fachbereichs 8 'Chemikalienbewertung'.

D-UBA (Umweltbundesamt, Berlin) http://www.umweltbundesamt.de

US-EPA (U.S. Environmental Protection Agency) http://www.epa.gov

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3 List of keywords

4 Annexes

4.1 Applications Liste von etwa 10(-20) Applikationen

4.2 Documents 4.2.1 DQ Specimen The pharmaceutics and medical sector, but increasingly the food range, too, are requesting various qualifications describing a suitable and properly functioning analysis system. In this context, the following abbreviations have the meaning opposite to them:

DQ Design Qualification „Pflichtenheft“ Prior to purchase IQ Installation Qualification „Installations-Qualifizierung“ Required dor installation OQ Operational Qualification „Arbeitsweisen-Qualifizierung“ Operation of the device PQ Performance Qualification „Leistungs-Qualifizierung“ Inspection of the device

4.2.2 IQ Specimen 4.2.3 OQ Specimen 4.2.4 PQ Specimen