hach - rapid liquid testingrapid liquid testing provides a fast, economical way to analyze multiple...

26578-88

RAPID LIQUID TESTING

© Hach Company, 1996All rights reserved. Printed in the U.S.A. 7040 dld/dp 02-02-96 1ed

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TABLE OF CONTENTS

OPERATION ..........................................................................................................1

INTRODUCTION ..................................................................................................3Rapid Liquid Testing ...........................................................................................3Rapid Liquid Reagents .........................................................................................3Use of Repipet Jr. Dispensers ..............................................................................3

Repipet Calibration ...........................................................................................4Changing Reagent Bottles ...................................................................................5Use of the Pour-Thru Cell ....................................................................................6Analytical Techniques for Low-level Analysis ...................................................7

PROCEDURES ......................................................................................................9Chlorine, Free ....................................................................................................11Chlorine, Total ...................................................................................................25Hardness, Total, Ultra Low Range ....................................................................33Iron .....................................................................................................................43Nitrite, Low Range ............................................................................................51Phosphorus, Reactive, Low Range ....................................................................65Phosphorus, Reactive, High Range ....................................................................85Silica, Ultra Low Range .....................................................................................93

GENERAL INFORMATION .............................................................................103

HOW TO ORDER ..............................................................................................105

REPAIR SERVICE .............................................................................................107

ADDITIONAL INFORMATION .......................................................................108

OPERATION

1

WARNINGHandling chemical samples, standards, and reagents can be dangerous. Review the necessary Material Safety Data Sheets and become familiar with all safety procedures before handling any chemicals.

ADVERTÊNCIAA manipulação de amostras, padrões e reagentes químicos pode ser perigosa. Reveja as necessárias Fichas Técnicas de Segurança do Material e familiarizese com os procedimentos de segurança antes de manipular quaisquer substãncias químicas.

ADVERTENCIALa manipulación de muestras químicas, patrones y reactivos puede ser peligrosa. Antes de manipular cualquier productor químico, conviene leer las Fichas Técnicas de Seguridad y familiarizarse con los procedimientos de sugeridad.

ATTENTIONLa manipulation des échantillons chimiques, étalons et réactifs peut être dangereuse. Lire les fiches de données de sécurité des produits nécessaires et se familiariser avec toutes les procédures de sécurité avant de manipuler tout produit chimique.

WARNUNGDa das Arbeiten mit chemikalischen Proben, Standards, Reagenzien und Abfällen mit Gefahren verbunden ist, empfiehlt die Hach Company dem Benutzer dieser Produkte dringend, sich vor der Arbeit mit sicheren Verfahrensweisen und dem richtigen Gebrauch der Chemikalien oder Biogefahrgut vertraut zu machen und alle entsprechenden Materialsicherheitsdatenblätter aufmerksam zu lesen.

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SECTION 1 INTRODUCTION

1.1 Rapid Liquid TestingRapid Liquid Testing provides a fast, economical way to analyzemultiple water samples. The use of liquid reagents, a convenientdispenser, and a Pour-Thru Cell allow for quick reagent additionand mixing with minimal sample handling.

1.2 Rapid Liquid ReagentsLiquid reagents are used with the Rapid Liquid Testing method toallow for fast reagent addition and mixing. However, somereagents are less stable in liquid form than they are in solid(powder) form. To ensure that these less-stable reagents willperform well, Hach has packaged them in two forms—powand liquid—which must be mixed together before use. Oncereagent is prepared, it must be used within the period of tnoted in each procedure; typically one month. The datepreparation should always be recorded on the reagent bottlthe age of the reagent can be determined.

Reagents left unused for longer than the time specified shouldiscarded and should not be added to freshly prepared reaSee the corresponding Material Safety Data Sheet (MSDScurrent Federal, State, and local regulations for dispoinformation. If the quality of a prepared reagent is in question,accuracy check (as specified in the procedures) can be perfousing a standard that is near the upper end of the range foanalysis. The test should give a result that is within 10% of value of the standard.

Some of the reagents used in Rapid Liquid analysis may hlabels suggesting they are to be used with a process analyzeris because many of the Rapid Liquid methods have been adafrom those of Hach process analyzers. The reagents are intefor Rapid Liquid Analysis as well as for process analyzers.

1.3 Use of Repipet Jr. DispensersRepipet dispensers can be directly attached to Hach reabottles for quick addition of reagent to samples. They mustassembled before initial use. The inlet tubing must be cut toproperly on the reagent bottle, and the dispenser must be prbefore initial use to minimize air bubbles in the dispenser. Seeinstruction and parts list provided with the Repipet dispensermore information.

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Take care to avoid contamination of the reagent when placingRepipet dispensers on the bottles. Rinse the inlet tubing andinside of the dispenser cap with copious amounts ofdemineralized water using a wash bottle. Place the inlet tubinginto a beaker of demineralized water and depress the plunger 10-15 times to rinse the inside of the dispenser. (For sensitiveanalysis in the low µg/L range, pour a small amount of reaginto the beaker of rinse water.) Remove the dispenser fromwater and depress the plunger until all of the rinse water has bexpelled. Shake off any excess water on the dispenser, placdispenser on the reagent bottle, and tighten.

1.3.1 Repipet CalibrationCalibration of Repipet Dispensers before initial use recommended for greatest accuracy. Calibrate Repipet dispenusing demineralized water. Each 1 mL dispensation should we1.00 gram. Repeated weighing of water dispensations adjustments of the Repipet are accomplished as follows:

1. Pre-weigh a small container using a top-loading balance.

2. Place the inlet tube of an assembled Repipet dispenser in beaker of water at room temperature and repeatedly deprethe plunger until no large air bubbles remain in the plungerbarrel. (Small air bubbles remaining should not affect the accuracy of the dispenser.)

3. Dispense the water repeatedly into the weighed container noting the weight of each dispensation. Each dispensationshould weigh 1.00 gram.

4. If the dispensation is more or less than one gram, adjust thvolume on the Repipet as follows:

a) Loosen the cap of the Repipet until the metal calibratlock ring moves back and forth.

b) Move the ring toward the negative (-) side to decrease amount of water dispensed or to the positive (+) sideincrease the amount. Retighten the cap. Each 10 µL adjustmentshould change the weight dispensed by 0.01 grams.

Example: If the amount of water initially dispensed was 0.9grams, move the metal ring to the positive (+) side approximately 20 µL and retighten. Depress the plunge

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repeatedly until several dispensations weigh 1.00 gram each.Repeat the adjustment if the weight is not 1.00 gram.

Note: Adjust the above procedure accordingly for dispenser volumes other than 1 mL.

Remove the cap from the reagent bottle. Screw the Repipetdispenser on the reagent bottle until tight, making sure the screwcap adapter inside the dispenser cap fits the reagent bottle.

Depress the plunger until large air bubbles are purged from thetubing (at least 4-5 times). Record the weight of one dispensationof reagent as in the calibration procedure above; use this weightto periodically check the calibration of the Repipet.

Over time the dispenser may give inconsistent or inaccurateresults. This may indicate that inlet or outlet valves need to bereplaced. See the instructions and the parts list provided with theRepipet dispenser for further information.

Place the outlet tip closure provided with the dispenser over theoutlet tip of the Repipet when not in use. If the Repipet dispenserhas been allowed to sit for several hours without use, depress theplunger 3 to 4 times to purge any large air bubbles.

Use of a TenSette® pipet is appropriate for reagent addition withsome Hach procedures but is not recommended for Rapid LiquidTesting due to potential contamination of reagent bottles. Seesection 1.6 Analytical Techniques for Low-level Analysis onpage 7 for more information.

1.4 Changing Reagent BottlesWhen the reagent is depleted, remove the dispenser from thereagent bottle. Rinse the dispenser by placing the inlet tube in abeaker of demineralized water and depressing the plunger 4-5times. Rinse the outside of the inlet tubing with demineralizedwater. Empty the dispenser by repeatedly depressing the plunger.

Place the dispenser on a fresh reagent bottle and tighten. Depress theplunger repeatedly until no large air bubbles remain in the plungerbarrel. Discard any unused reagent from the previous bottle. Do nottransfer leftover reagent from a used bottle to a fresh one.

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Over time the dispenser may give inconsistent or inaccurateresults. This may indicate that inlet or outlet valves need to bereplaced. See the instructions and the parts list provided with theRepipet dispenser for further information.

Place the outlet tip closure provided with the dispenser over theoutlet tip of the Repipet when not in use. If the Repipet dispenserhas been allowed to sit for several hours without use, depress theplunger 3 to 4 times to purge any large air bubbles.

Use of a TenSette® pipet is appropriate for reagent addition withsome Hach procedures but is not recommended for Rapid LiquidTesting due to potential contamination of reagent bottles.

1.5 Use of the Pour-Thru CellSamples for any one analysis method can typically be poured intothe Pour-Thru Cell in succession without rinsing the cell.However, it is advisable to rinse the Pour-Thru Cell when goingfrom a concentrated to a dilute sample and when the next sampleis not yet ready for analysis.

When switching from one analysis method to another, it isimportant to prevent contamination in the next analysis. Forexample, if a Total Chlorine analysis is followed by a FreeChlorine analysis, any remaining reagent left in the Pour-ThruCell from the Total Chlorine analysis can interfere with the FreeChlorine analysis.

To prevent contamination when changing from one analysis toanother, rinse the Pour-Thru Cell thoroughly. First rinse thefunnel of the Pour-Thru Cell with demineralized water using awash bottle, then pour at least 50 mL of demineralized water intothe funnel.

A reagent rinse of the Pour-Thru Cell with a dilute solution of thereagent to be used in the next analysis will further reduce thepossibility of contamination.

If reagents have been allowed to sit in the Pour-Thru Cell for longperiods of time, a build-up of colored products may develop. Thisbuild-up can be removed by rinsing with either acid or base; mostprocedures specify which to use. When not in use, place a smallbeaker over the glass funnel of the Pour-Thru Cell.

For additional information on using the Pour-Thru Cell, refer to

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the DR/2000 or DR/3000 instrument manual.

1.6 Analytical Techniques for Low-level AnalysisMany of the analyses available with Rapid Liquid Testing allowfor the detection of very low levels of analytes. When measuringlow analyte concentrations, it is very important to controlcontamination throughout the analysis. Keeping containers suchas screw-cap flasks closed when not in use, covering the Pour-Thru Cell when not in use, and rinsing and inverting graduatecylinders immediately after use will minimize contaminationfrom outside sources.

Keeping labware clean is extremely important in low-levelanalysis. Initial cleaning of labware should include a reagentrinse, where a dilute solution of the reagent to be used is added tothe labware to react with any analyte not removed by normalcleaning. If the labware is not used for other analyses, onlyoccasional reagent rinses are necessary.

Dedicating labware for use on only one test method reduces thepossibility that reagents from one analysis will contaminateanother. For instance, the reagents used in the Total Chlorine testwill interfere with the Free Chlorine test.

All measurements in low-level analysis should be made withcare. This is especially true when preparing standards foraccuracy checks. Use only Class A labware and high qualitydemineralized water.

To control reagent contamination, avoid placing anything (suchas a pipet) into a reagent bottle. (Repipet dispensers will notcontaminate reagent bottles if they are thoroughly cleaned beforebeing attached to the bottles. See the section titled Use of theRepipet Jr. Dispenser for cleaning instructions.) If reagent mustbe taken from a bottle without using the Repipet dispenser, pour asmall amount into another container and pipet from thatcontainer. Do not return any solution to the original reagentbottle.

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PROCEDURES

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Handling chemical samples, standards, and reagents can be dangerous.

Review the necessary Material Safety Data Sheets and become familiar with all safety procedures before handling any chemicals.

Method 10059

CHLORINE, FREE (0 to 2.00 mg/L)DPD Rapid Liquid Method*For DR/2000 and DR/3000 Instruments For treated water

* Adapted from Standard Methods for the Examination of Water and Wastewater

1. Enter the stored program number for free and total chlorine (Cl2).

Press:

8 2 READ/ENTER

The display will show:

DIAL nm to 530

Note: DR/2000s with software versions 3.0 and greater will display “P” and the program number.

Note: Instruments with software versions 3.0 and greater will not display the “DIAL nm to” message if the wavelength is already set correctly. The display will show the message in Step 3. Proceed with Step 4.

Note: Samples must be analyzed immediately and cannot be preserved for later analysis.

Note: For instruments that do not have this stored program, refer to Instrument Setup following these steps.

Note: For DR/3000s:Press: Manual ProgramPress 1.851 Conc Factor

2. Rotate the wavelength dial until the small display shows:

530 nm

Note: For DR/3000s, set the wavelength to 530 nm.

3. Press:

READ/ENTER


mg/l Cl2 RL

Note: For DR/3000s:Press: 10 Signal AveragePress: ZeroPress: 2 Conc

4. Install the Pour-Thru Cell and flush with 50 mL of demineralized water.

Note: Clean the Pour-Thru Cell and all labware as specified under Analysis Labware.

Note: The windows of the Pour-Thru Cell should face side-to-side in the DR/2000 and front-to-back in the DR/3000.

530 nm

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CHLORINE, FREE, continued

5. Pour approximately 50 mL of sample into the Pour-Thru Cell.

6. When the flow has stopped, press:

ZERO


WAIT

then:

0.00 mg/l Cl2 RL

Note: For the DR/3000: Press: Zero Conc

7. Add 1.0 mL of Free Chlorine Buffer Solution to a clean, dry 100-mL glass mixing cylinder using the Repipet dispenser.

8. Add 1.0 mL of prepared Free Chlorine Indicator Solution to the same mixing cylinder. Swirl to mix the reagents. Proceed to step 9 immediately.

Note: See Reagent Preparation for instructions on preparing the indicator solution.

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Sampling and StorageSamples must be analyzed immediately and cannot be preservedfor later analysis. A common testing error is introduced if theanalyst does not obtain a representative sample. If sampling froma tap, let the water flow for at least five minutes to ensure arepresentative sample. Let the container overflow with the sampleseveral times, then cap the sample container so there is noheadspace (air) above the sample. Perform the chlorine analysisimmediately.

9. Carefully fill the mixing cylinder to the 80-mL mark with sample. Stopper the cylinder and gently invert it twice to mix. Proceed to step 10 immediately.

10. Fill the funnel of the Pour-Thru Cell with the reacted sample from the mixing cylinder.

Note: It is not necessary to pour the entire sample into the Pour-Thru Cell; approximately half of the sample may be discarded.

11.After the flow has stopped, press:

READ/ENTER


WAIT

then the result in mg/L chlorine (Cl2) will be displayed.

Note: If the display flashes 2.20, dilute a fresh sample and repeat the test. A slight loss of chlorine may occur during the dilution. Multiply the result by the appropriate dilution factor; see Sample Dilution Techniques in Section I of the DR/2000 or DR/3000 Procedures manual.

Note: In the constant-on mode, pressing READ/ENTER is not required. WAIT will not appear. When the display stabilizes, read the result.

12.Flush the Pour-Thru Cell with at least 50 mL of demineralized water immediately after use.

Note: Protect the Pour-Thru Cell from contamination by inverting a small beaker over the top of the glass funnel when not in use.

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ofing

Avoid plastic containers since these may have a chlorine demand. Pre-treat glass sample containers to remove any chlorine demandby soaking in a dilute bleach solution (1 mL commercial bleachto l liter of demineralized water) for at least 1 hour. Rinsethoroughly with demineralized water.

If sample containers are rinsed thoroughly with demineralizedwater after use, only occasional pretreatment is necessary. A pre-treated BOD bottle with a ground-glass stopper makes an idealsample container for chlorine analysis.

Analysis LabwareGlassware used in this test must be chlorine demand-free. Fill the100 mL mixing cylinder and sample container with a dilutesolution of chlorine bleach prepared by adding 1 mL ofcommercial bleach to 1 liter of water. Soak in this solution at leastone hour. After soaking, rinse with copious amounts ofdemineralized water and allow to dry before use. If the mixingcylinder is thoroughly rinsed with demineralized water andallowed to dry after each use, only occasional pretreatment isnecessary. Do not use the same mixing cylinder for Free and TotalChlorine analysis.

Treat the Pour-Thru Cell similarly with dilute bleach and let standfor several minutes. Rinse several times with demineralized water.

Cleaning the Pour-thru CellThe Pour-Thru Cell may accumulate a buildup of coloredreaction products, especially if the reacted solutions are allowedto remain in the cell for long periods after measurement. Removethe buildup by rinsing the cell with 5.25 N Sulfuric Acid followedby several rinsings with demineralized water.

Reagent PreparationThe Free Chlorine Indicator Solution must be prepared beforeuse. Using a powder funnel, add the contents of one 24 g bottle ofDPD Powder (Cat. No. 22972-55) to one 473-mL bottle of FreeChlorine Indicator Solution (Cat. No. 23140-11). Invert severaltimes and swirl until the powder is completely dissolved. A pinkcolor may develop, but should not affect results.

This solution will give accurate results for at least one month aftermixing when stored at 20-25 °C (68-77 °C). Write the datepreparation on the Indicator Solution Bottle. Discard any remain

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negle9%

solution after one month. Use of this reagent after one month mayresult in high reagent blanks and low values at high concentration.Do not combine fresh reagent with previously mixed reagent.

Accuracy CheckStandard Additions Method

a) Snap the top off a Chlorine Voluette Ampule StandardSolution, 50 to 75 mg/L Cl2.

b) Use the TenSette Pipet to add 0.3, 0.6 and 0.9 mL of standardto three 80-mL samples, respectively. Swirl gently to mix.

c) Analyze each sample as described above. Each 0.3 mL ofstandard will cause an incremental increase in chlorine,the exact value of which depends on the concentration inthe ampule. Check the certificate enclosed with theampules for this value.

d) Calculate the concentration of chlorine added to eachsample as follows:

Example:

e) If the concentration of each sample does not increase bythe calculated amount, refer to Standard Additions inSection I of the DR/2000 or DR/3000 Procedures Manualfor more information.

PrecisionDR/2000: In a single laboratory using 8 concentrations of chlorinestandards and two lots of reagents with a DR/2000, a singleoperator obtained a calibration curve that showed a 99%confidence interval at 1.00 mg/L of ±0.004 mg/L chlorine.

DR/3000: In a single laboratory using 8 concentrations of chloristandards and two lots of reagents with a DR/3000, a sinoperator obtained a calibration curve that showed a 9confidence interval at 1.00 mg/L of ±0.004 mg/L chlorine.

mL of standard additionmL of standard addition mL of sample+---------------------------------------------------------------------------------------------------------- chlorine concentration in ampule

concentration of chlorine added to the sample=

×

0.3 mL80.3 mL---------------------- 72.3 mg/L× 0.27 mg/L chlorine added to the sample=

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InterferencesSamples containing more than 400 mg/L alkalinity may notdevelop the full amount of color, or it may instantly fade.Neutralize these samples to a pH of 6 to 7 with 1 N Sulfuric Acid.Determine the amount required on a separate 80-mL sample, thenadd the same amount to the sample to be tested.

Samples containing monochloramine will cause a gradual drift tohigher chlorine readings. When read within one minute of reagentaddition, 3.0 mg/L monochloramine will cause an increase of lessthan 0.1 mg/L in the free chlorine reading.

Note: If sodium arsenite is used, collect the spent sample for proper disposal according to the hazardous waste regulations for arsenic. Refer to the DR/2000 or DR/3000 Instrument Manual for information on modifying the Pour-Thru Cell for collecting the sampleafter analysis.

Bromine, iodine, ozone and oxidized forms of manganese also mayreact and show as chlorine. Hexavalent chromium at levels >1 mg/L will cause a positive interference.

To compensate for the effects of manganese (Mn4+) or chromium(Cr6+), adjust pH to 6 to 7 as described above, then add 9 drops ofpotassium iodide, 30 g/L, to 80 mL of sample, mix and wait 1minute. Add 9 drops of sodium arsenite, 5 g/L, and mix. Analyzethis sample as described above. (If chromium is present, allowexactly the same reaction period with the DPD for both analyses.)Subtract the result of this test from the original analysis to obtainthe accurate chlorine result.

Hardness at levels below 1000 mg/L as CaCO3 will not interfere.

Summary of MethodChlorine in the sample as hypochlorous acid or hypochlorite ion(free chlorine or free available chlorine) immediately reacts withDPD (N,N-diethyl-p-phenylenediamine) indicator to form a redcolor which is proportional to the chlorine concentration.

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REQUIRED REAGENTS Description Cat. No.DPD Indicator Powder, 24 g .........................................................................................22972-55Free Chlorine Indicator Solution, 473 mL ....................................................................23140-11Free Chlorine Buffer Solution, 473 mL ........................................................................23141-11

REQUIRED APPARATUS Cylinder, mixing, glass, 100 mL, each............................................................................1896-42Dispenser, fixed volume, 1.0 mL Repipet Jr., each (two required) ...............................21113-01Pour-Thru Cell Assembly Kit, DR/2000, each .............................................................45215-00Pour-Thru Cell Assembly Kit, DR/3000, each .............................................................19941-00

OPTIONAL REAGENTSChlorine Standard Solution, Voluette Ampule, 50-75 mg/L, 10 mL, 16/pkg ......................................................................................14268-10Chlorine Standard Solution, Voluette Ampule, 50-75 mg/L, 2 mL, 20/pkg ........................................................................................14268-20Potassium Iodide Solution, 30 g/L, 100 mL* MDB .........................................................343-32Sodium Arsenite, 5 g/L, 100 mL* MDB ........................................................................1047-32Sodium Hydroxide Standard Solution, 1.000 N, 100 mL* MDB...................................1045-32Sulfuric Acid Standard Solution, 1.000 N, 100 mL* MDB............................................1270-32Sulfuric Acid Standard Solution, 5.25 N, 1 L .................................................................2449-53Water, demineralized, 4 L ................................................................................................272-56

OPTIONAL APPARATUSAmpule Breaker Kit, each ........................................................................................................... 21968-00Beaker, poly, 50 mL ...................................................................................................................... 1080-41Bottle, wash, 125 mL, each ......................................................................................................... 21901-43Bottle, BOD, w/stopper, 300 mL ................................................................................................... 621-00Funnel, powder, each................................................................................................................... 22644-67pH Meter, EC10, portable, each ................................................................................................. 50050-00Pipet, TenSette, 0.1 to 1.0 mL, each ........................................................................................... 19700-01Pipet Tips, for 19700-01 TenSette Pipet, 50/pkg ....................................................................... 21856-96

* Contact Hach for larger sizes.

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INSTRUMENT SETUPWhen this instrument setup has been entered into the instrument,the user may perform either the Free or Total Chlorine procedure.The timed step is entered for the total chlorine procedure anddoes not affect the function of the free chlorine procedure.

DR/2000 with 1.261 and 1.27 softwareEnter the calibration as an operator-programmed calibration.Follow the steps in the Operation section of the DR/2000Instrument Manual. Store the method as follows:

nm = 530Decimal = 00.00Units = mg/l Symbol = Cl2 RLTimer 1 = 1:00

Enter the calibration with 0.000 absorbance values for zero and #1standard. With the sample cell compartment empty, begin bystoring standards 0 and 1 as the concentrations shown in the tablebelow. Accept 0.000 Abs as the absorbance value for all standards.Store the calibration values by pressing SHIFT READ/ENTER.

Next, edit the absorbance values for the standards to the valuesgiven below. Follow the steps given in the Operations section ofthe DR/2000 Instrument Manual.

The method is now stored as an operator-programmed methodnumber between 950 and 999. Record the method number forfuture reference.

DR/2000 with Software Versions 2.0 and 2.2Enter the calibration as an update to Hach stored programs.

1. Press:

Std. Conc Abs

# 0 0.00 0.000

# 1 2.20 1.166

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2. Press:

3. Press:

4. Within 3 seconds, press:

The display will show: ENTER nm

5. Press:

Press READ/ENTER. If you make an error, press SHIFT CLEAR and re-enterthe number. When the number is correct, press READ/ENTER.The display will show: DECIMAL? 00.00

6. The decimal point is correctly positioned. Press: READ/ENTER.

7. The display will show: UNITS?

8. Use the arrow keys to select the appropriate unit of measure. Press the DOWN ARROW key twice. The display will show: mg/l

9. Press READ/ENTER when the correct unit of measure is displayed. The display will show: SYMBOL?

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10. Construct the correct symbol display: Cl2 RL

a) Select letters and regular numbers by scrolling to thecorrect symbol with the ARROW keys.

b) To make a letter uppercase, press the SHIFT key.

c) To enter subscript numbers, enter the digit on the numerickeypad.

d) To enter superscript numbers, enter the digit on thenumeric keypad number then make it a superscript bypressing SHIFT.

e) The space is the character displayed after one press of thedown arrow.

f) Accept each symbol by pressing READ/ENTER.

g) To end symbol entry, press READ/ENTER a second timeafter accepting the last character.

11. When the instrument is out of symbol entry mode, the display will show: TIMER?

12. The method for Total Chlorine has one timed step, so press SHIFT TIMER. The display will show: MM:SS TIME 1?

13. Enter a timer value of 1 minute. Press:

14. Press READ/ENTER to accept the timer value. The display will show: MM:SS TIME 2?

15. Press READ/ENTER to complete the timer entry. The display will show: #1 Data

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16. Enter the following 12 numbers as shown. Complete each number entry by pressing the READ/ENTER key.

The final number is a check value which determines if the datasequence was correctly entered. If an error was made duringnumber entry, the display will return to the prompt for data # 1and the entire sequence must be re-entered. If all numbers arecorrectly entered, the display will return to the method promptand is ready for use.

DR/2000 with Software Version 3.0 and Above1. Turn the instrument on. Press SHIFT METHOD to enter

configuration mode. The display will show: MOMENTARY or CONSTANT ON

2. Press the UP ARROW key twice to select HACH UPDATE. Press: READ/ENTER. The display will show: ENTER #:

3. Press:

The display will show: P 82 ENTER nm

4. Press:

The display will show: P 82 DECIMAL? 00.00

# 1 Data 0# 2 Data 6167

# 3 Data 6167# 4 Data 6168# 5 Data 5912

# 6 Data 5912# 7 Data 65535# 8 Data 65535

# 9 Data 65535#10 Data 13107#11 Data 512

Checksum 21594

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Note: If you make an error, press SHIFT CLEAR and re-enter the number. When the number is correct, press READ/ENTER.

5. The decimal point is correctly positioned. Press READ/ENTER. The display will show: P 82 UNITS?

6. Use the ARROW keys to select the appropriate unit of measure. Press the DOWN ARROW key twice.The display will show: P 82 mg/l

7. Press READ/ENTER when the correct unit of measure is displayed. The display will show: P 82 mg/l _

8. Construct the display to read the correct symbol. The symbol must be entered exactly as shown including dashes and spaces between characters: Cl2 RL

a) Select letters and numbers by scrolling to the correctcharacter with the arrow keys.

b) To make a letter uppercase, press the SHIFT key.

c) Make a number or sign superscript, subscript or regular bypressing SHIFT until the symbol is correct. The 2 in thesymbol must be shifted to subscript.

d) The space is the character displayed after one press of thedown arrow.

e) Make sure to enter the display line EXACTLY as shown,including all spaces. Do not enter trailing spaces.


g) When the last character of the symbol is accepted with theREAD/ENTER key, press READ/ENTER a second time to enddisplay entry mode.

9. When the instrument is out of symbol entry mode, the display will show: P82 TIMER

10. This method has one timed step, so press SHIFT TIMER. The display will show: MM:SS TIME 1?

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11. Enter a timer value of 1 minute. Press:

12. Press READ/ENTER to accept the timer value. The display will show: MM:SS TIME 2?

13. Press READ/ENTER to complete the timer entry. The display will show: #0 STANDARD

14. Press READ/ENTER to display the zero data pair. The display will show: 0.000 Abs 00.00 mg/l Press READ/ENTER. The display will show: # 1 STANDARD

15. Press READ/ENTER. The display will prompt for entry of the first concentration point: # 1 00.00 mg/l

16. Enter concentration point #1 from the table below by pressing

so that the display shows: # 1 02.20 mg/l

17. Press READ/ENTER. The display will prompt for entry of the first absorbance point: # 1 0.000 Abs

18. Enter absorbance point #1 from the table below by pressing

so that the display shows: # 1 1.166 Abs

19. Press READ/ENTER. The display will show the first data pair: 1.166 Abs 02.20 mg/l

20. Press READ/ENTER to accept the first data pair. The display will show: # 2 STANDARD

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21. The data pair values from the table below are now entered.

22. When the last point pair is entered, the display will show: # 2 STANDARD

23. Press SHIFT READ/ENTER to complete data point entry The display will show: #:

24. Enter the validation number:

so that the display shows: #: 2444

25. Press READ/ENTER. The display will show: COMPLETED then: P82 mg/l Cl2 RL

If the display shows: INCORRECT # then prompts again for thevalidation number, you may have made an error during data entry.Make sure that the validation number is correct. If so then theerror occurred during some other portion of the method entry.You must press METH and respond to the ABORT? message bypressing READ/ENTER, then re-enter the method.

The instrument is now ready for use with method 82.

Standard Concentration Absorbance

# 0 [ 0.00] mg/l [0.000] Abs

# 1 [ 2.20] mg/l [1.166] Abs

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Method 10060

CHLORINE, TOTAL (0 to 2.00 mg/L)DPD Rapid Liquid Method *

For DR/2000 and DR/3000 Instruments For treated water

* Adapted from Standard Methods for the Examination of Water and Wastewater

1. Enter the stored program number for free and total chlorine (Cl2).

Press:

8 2 READ/ENTER


DIAL nm TO 530


Note: Instruments with software versions 3.0 and greater will not display “DIAL nm TO” message if the wavelength is already set correctly. The display will show the message in Step 3. Proceed with Step 4.

Note: Samples must be analyzed immediately and cannot be preserved for later analysis.

Note: For instruments that do not have this stored program, refer to the Free Chlorine Instrument Setup on page 18.

Note: For DR/3000s:Press: Manual ProgramPress 1.851 Conc Factor


530 nm

Note: For DR/3000s, set the wavelength to 530 nm.

3. Press:

READ/ENTER


mg/l Cl2 RL

Note: For DR/3000s:Press: 10 Signal AveragePress: ZeroPress: 2 Conc


Note: Clean the Pour-Thru Cell and all labware as specified under Analysis Labware.

Note: The windows of the Pour-Thru Cell should face side-to-side in the DR/2000 and front-to-back in the DR/3000.

530 nm

25

CHLORINE, TOTAL, continued

5. Pour approximately 50 mL of sample into the Pour-Thru Cell.

6. When the flow has stopped, press:

ZERO


WAIT

then:

0.00 mg/l Cl2 RL

Note: For the DR/3000: Press: Zero Conc

7. Add 1.0 mL of Total Chlorine Buffer Solution to a clean, dry glass 100-mL mixing cylinder using the Repipet dispenser.

8. Add 1.0 mL of prepared Total Chlorine Indicator Solution to the same mixing cylinder. Swirl to mix the reagents. Proceed to step 9 immediately.

Note: See Reagent Preparation for instructions on preparing the indicator solution.

26


9. Carefully fill the mixing cylinder to the 80-mL mark with sample. Stopper the cylinder and gently invert it twice to mix.

10.Press:SHIFT TIMER

A one-minute reaction time will begin.

Note: For the DR/3000, press: 1 Timer

11.When the timer beeps, fill the funnel of the Pour-Thru Cell with the reacted sample from the mixing cylinder.

Note: It is not necessary to pour the entire sample into the Pour-Thru Cell; approximately half of the sample can be discarded.


READ/ENTER


WAIT

then the result in mg/L chlorine (Cl2) will be displayed.

Note: For the DR/3000:Press: Conc

Note: Complete this step within two minutes after the timer beeps.

Note: If the display flashes 2.20, or shows OVER-RANGE, dilute a fresh sample and repeat the test. A slight loss of chlorine may occur during the dilution. Multiply the result by the appropriate dilution factor; see Sample Dilution Techniques in Section I of the DR/2000 or DR/3000 Procedures Manual.


27


Sampling and StorageSamples must be analyzed immediately and cannot be preserved forlater analysis. A common testing error is introduced if the analystdoes not obtain a representative sample. If sampling from a tap, letthe water flow for at least five minutes to ensure a representativesample. Let the container overflow with the sample several times,then cap the sample container so there is no headspace (air) above thesample. Perform the chlorine analysis immediately.

Avoid plastic containers since these may have a chlorine demand.Pre-treat glass sample containers to remove any chlorine demandby soaking in a dilute bleach solution (1 mL commercial bleachto l liter of demineralized water) for at least 1 hour. Rinsethoroughly with demineralized water. If sample containers arerinsed thoroughly with demineralized water after use, onlyoccasional pretreatment is necessary. A pre-treated BOD bottlewith a ground-glass stopper makes an ideal sample container forchlorine analysis.



28

ofnyoneighsly


Analysis LabwareGlassware used in this test must be chlorine demand-free. Fill the100 mL mixing cylinder and sample container with a dilutesolution of chlorine bleach prepared by adding 1 mL ofcommercial bleach to 1 liter of water. Soak in this solution at leastone hour. After soaking, rinse with copious amounts ofdemineralized water and allow to dry before use. If the mixingcylinder is rinsed thoroughly with demineralized water andallowed to dry after use, only occasional pretreatment isnecessary. Do not use the same mixing cylinder for Free and TotalChlorine analysis.

Treat the Pour-Thru Cell similarly with dilute bleach and let standfor several minutes. Rinse several times with demineralized water.

Cleaning the Pour-thru CellThe Pour-Thru Cell may accumulate a buildup of colored reactionproducts, especially if the reacted solutions are allowed to remainin the cell for long periods after measurement. Remove thebuildup by rinsing the cell with 5.25 N sulfuric acid followed byseveral rinsings with demineralized water.

Reagent PreparationThe Total Chlorine Indicator Solution must be prepared beforeuse. Using a powder funnel, add the contents of one 24 g bottle ofDPD Powder (Cat. No. 22972-55) to one 473-mL bottle of TotalChlorine Indicator Solution (Cat. No. 22634-11). Invert severaltimes and swirl until the powder is completely dissolved. A pinkcolor may develop, but should not affect results.

This solution will give accurate results for at least one month aftermixing when stored at 20-25 °C (68-77 °C). Write the datepreparation on the Indicator Solution Bottle. Discard aremaining solution after one month. Use of this reagent after month may result in high reagent blanks and low values at hconcentration. Do not combine fresh reagent with previoumixed reagent.

29

negle9%



a) Snap the top off a Chlorine Voluette Ampule StandardSolution, 50-75 mg/L Cl2.

b) Use the TenSette Pipet to add 0.3, 0.6 and 0.9 mL of standardto three 80-mL samples, respectively. Swirl gently to mix.

c) Analyze each sample as described above. Each 0.3 mL ofstandard will cause an incremental increase in chlorine,the exact value of which depends on the concentration inthe ampule. Check the certificate enclosed with theampules for this value.

d) Calculate the concentration of chlorine added to eachsample as follows:

Example:

e) If the concentration of each sample does not increase bythe calculated amount, refer to Standard Additions inSection I of the DR/2000 or DR/3000 Procedures Manualfor more information.

PrecisionDR/2000: In a single laboratory using 9 concentrations of chlorinestandards and two lots of reagents with a DR/2000, a singleoperator obtained a calibration curve that showed a 99%confidence interval at 1.00 mg/L of ±0.005 mg/L chlorine.

DR/3000: In a single laboratory using 9 concentrations of chloristandards and two lots of reagents with a DR/3000, a sinoperator obtained a calibration curve that showed a 9confidence interval at 1.00 mg/L of ±0.005 mg/L chlorine.

mL of standard additionmL of standard addition mL of sample+---------------------------------------------------------------------------------------------------------- chlorine concentration in ampule

concentration of chlorine added to the sample=

×

0.3 mL80.3 mL---------------------- 72.3 mg/L× 0.27 mg/L chlorine added to the sample=

30


InterferencesNote: If sodium arsenite is used, collect the spent sample for proper disposal according to the hazardous waste regulations for arsenic. Refer to the DR/2000 Instrument Manual for information on modifying the Pour-Thru Cell for collecting samples after analysis.

Samples containing more than 700 mg/L alkalinity may notdevelop the full amount of color, or it may instantly fade.Neutralize these samples to a pH of 6 to 7 with 1 N sulfuric acid.Determine the amount required on a separate 80-mL sample; thenadd the same amount to the sample to be tested.

Bromine, iodine, ozone and oxidized forms of manganese alsomay react and show as chlorine. Hexavalent chromium a levels >1mg/L will cause a positive interference.

To compensate for the effects of manganese (Mn4+) or chromium(Cr6+), adjust pH to 6 to 7 as described above, then add 9 drops ofpotassium iodide, 30 g/L, to 80 mL of sample, mix and wait 1minute. Add 9 drops of sodium arsenite, 5 g/L, and mix. Analyzethis sample as described above. (If chromium is present, allowexactly the same reaction period with the DPD for both analyses.)Subtract the result of this test from the original analysis to obtainthe accurate chlorine result.

Hardness at levels below 1000 mg/L as CaCO3 will not interfere.

Summary of MethodChlorine can be present in water as free available chlorine and ascombined available chlorine. Both forms can exist in the samewater and can be determined together as the total availablechlorine. Free chlorine is available as hypochlorous acid orhypochlorite ion. Combined chlorine exists as monochloramine,dichloramine, nitrogen trichloride and other chloro derivatives.

The combined chlorine oxidizes iodide in the reagent to iodine.The iodine reacts with DPD (N,N-diethyl-p-phenylenediamine)indicator along with free chlorine present in the sample to form ared color which is proportional to the total chlorine concentration.To determine the concentration of combined chlorine, run a freechlorine test. Subtract the results from the results of the totalchlorine test to obtain combined chlorine.

31

8. Ifdure,


REQUIRED REAGENTS Description Cat. No.DPD Indicator Powder, 24 g........................................................................................................ 22972-55Total Chlorine Indicator Solution, 473 mL ................................................................................. 22634-11Total Chlorine Buffer Solution, 473 mL...................................................................................... 22635-11

REQUIRED APPARATUS Cylinder, mixing, glass, 100 mL, each .......................................................................................... 1896-42Dispenser, fixed volume, 1.0 mL RePipet Jr., each (two required) ............................................. 21113-01Pour-Thru Cell Assembly Kit, DR/2000, each............................................................................ 45215-00Pour-Thru Cell Assembly Kit, DR/3000, each............................................................................ 19941-00

OPTIONAL REAGENTSChlorine Standard Solution, Voluette Ampule, 50-75 mg/L, 10 mL, 16/pkg .................................................................................................... 14268-10Chlorine Standard Solution, Voluette Ampule, 50-75 mg/L, 10 mL, 20/pkg .................................................................................................... 14268-20Potassium Iodide Solution, 30 g/L, 100 mL* MDB ........................................................................ 343-32Sodium Arsenite, 5 g/L, 100 mL* MDB ...................................................................................... 1047-32Sodium Hydroxide Standard Solution, 1.000 N, 100 mL* MDB ................................................. 1045-32Sulfuric Acid Standard Solution, 1.000 N, 100 mL* MDB .......................................................... 1270-32Sulfuric Acid Standard Solution, 5.25 N, 1 L ............................................................................... 2449-53Water, demineralized, 4 L ............................................................................................................... 272-56

OPTIONAL APPARATUSAmpule Breaker Kit, each ........................................................................................................... 21968-00Beaker, poly, 50 mL....................................................................................................................... 1080-41Bottle, Wash, 125 mL each.......................................................................................................... 21901-43Bottle, BOD, w/stopper, 300 mL .................................................................................................... 621-00Funnel, powder, each................................................................................................................... 22644-67pH Meter, EC10, portable, each ................................................................................................. 50050-00Pipet, TenSette, 0.1 to 1.0 mL, each ........................................................................................... 19700-01Pipet Tips, for 19700-01 TenSette Pipet, 50/pkg ........................................................................ 21856-96

INSTRUMENT SETUPThe instrument setup for this procedure is identical to the setup forthe Free Chlorine procedure. If you need to enter the setup intoyour instrument’s memory, please refer to that setup on page 1you have already entered the setup for the Free Chlorine proceit is not necessary to enter it again.

* Contact Hach for larger sizes.

32

Method 8374

HARDNESS, TOTAL, ULTRA LOW RANGE (0 to 1,000 µg/L Ca & Mg as CaCO3) Calcium and Magnesium; Chlorophosphonazo Rapid Liquid MethodFor DR/2000 and DR/3000 Instruments For boiler, cooling, and ultra-pure waters

1. Enter the stored program number for ultra low range hardness.

Press:

2 2 7 READ/ENTER


DIAL nm to 669

Note: For DR/2000s without this stored program, see Instrument Setup following these steps.

Note: for DR/3000s,Press: Manual ProgramPress: -723.8 Conc Factor


669 nm

Note: For DR/3000s, set the wavelength to 669.0 nm.

3. Press: READ/ENTER


µg/l as CaCO3

Note: For DR/3000s, Press: 10 Signal AveragePress: ZeroPress: 0 Conc

4. Install the Pour-Thru Cell and flush with 50 mL of ultra-pure water.

Note: Pre-clean the Pour-Thru Cell and all labware as specified in the Analysis Labware section of this procedure.

Note: Make sure the windows of the Pour-Thru Cell face side-to-side in the DR/2000 and front-to-back in the DR/3000.

5. Rinse a clean 125-mL plastic Erlenmeyer flask three times with the sample.

6. Rinse a clean 50-mL plastic graduated cylinder three times with the sample.

7. Fill this rinsed cylinder to the 50-mL mark with sample.

8. Pour the contents of the 50-mL cylinder into the flask.

699 nm

33

HARDNESS, TOTAL, ULTRA LOW RANGE, continued

9. Add 2.0 mL of Chlorophosphonazo Reagent to the sample using the Repipet Dispenser. Swirl to mix.

10.Pour approximately half (25 mL) of the sample into the Pour-Thru Cell.

Note: A clean, dry, plastic 25-mL graduated cylinder may be used for measuring half of the sample.


ZERO


WAIT

then

0 µg/l as CaCO3

Note: For DR/3000s,Press: Zero Conc

12.Add one drop of CDTA Reagent for Ultra Low Range Hardness to the remaining sample in the flask. Swirl to mix.

Note: Complete steps 13-14 within 1-2 minutes.

34


Analysis LabwareClean all containers used in this test thoroughly to remove any traces ofcalcium or magnesium. If possible, use plastic containers for allanalysis and storage. Clean containers by normal means, then rinsewith ultra-pure (aldehyde-free) water. Fill and soak for 10 minutes witha 1:25 dilution of Chlorophosphonazo Reagent in ultra-pure water.Rinse well with ultra-pure water. Keep containers tightly closed anddedicate them for ULR Hardness only. If containers are rinsed andcapped after each use, only occasional soaking is necessary. Fill thePour-Thru Cell with this same mixture of chlorophosphonazo andwater and let stand for several minutes. Rinse with ultra-pure water.

13.Pour the remaining sample into the Pour-Thru Cell.


READ/ENTER


WAIT

then the result in µg/L as CaCO3 will be displayed.


Note: If the sample concentration is greater than 750 µg/L, a 1:1 dilution of the sample is recommended for greatest accuracy. Use ultra-pure (aldehyde-free) water for the dilution. Repeat the analysis on the diluted sample and multiply the resulting concentration by 2.

15.Rinse the Pour-Thru cell with ultra-pure water using a wash bottle immediately after use.

16.Flush the Pour-Thru cell with an additional 50 mL of ultra-pure water.

Note: Protect the Pour-Thru cell from contamination by inverting a small beaker overthe top of the glass funnel when not in use.

35

s inual

ion

as


36

Avoid contamination of the Chlorophosphonazo Reagent bottlewhen placing the Repipet dispenser on the bottle. Rinse the inlettubing and inside of the dispenser cap with copious amounts ofultra-pure water using a wash bottle. Place the inlet tubing into abeaker of ultra-pure water and depress the plunger 10-15 times torinse the inside of the dispenser. (For best results, pour a smallamount of reagent into the beaker of rinse water.) Remove thedispenser from the water and depress the plunger until all of thewater has been expelled. Shake off any excess water on thedispenser, place the dispenser on the bottle, and tighten.

Sampling and StorageDo not use glass containers. Collect samples in clean plasticcontainers, preferably with screw-type closures. Rinse containersseveral times with the water to be analyzed before capturing thefinal sample. Seal to avoid contamination during transport.Analyze as soon as possible.


a) Use a TenSette Pipet to add 0.2 mL, 0.4 mL, and 0.6 mL,of a 20 mg/L (as CaCO3) Calcium Chloride standard tothree 50-mL samples, respectively.

b) Perform the hardness test on each sample as described above.

c) Each 0.2 mL addition of standard should cause an increaseof 80 µg/L hardness as CaCO3.

d) If these increases do not occur, see Standard AdditionSection I of the DR/2000 or DR/3000 Procedures Manfor more information.

Standard Solution MethodUse the 0.50 mg/L (as CaCO3) Calcium Chloride StandardSolution listed under Optional Reagents. Analyze this solutaccording to the above procedure.

The strength of this standard solution is 0.50 mg/L as CaCO3 (or 500 µg/L); the analytical result should be between 460 µg/LCaCO3 and 540 µg/L as CaCO3.

g/L0, a

g/L0, a

vels

ureing

herbsntance(as


PrecisionDR/2000: In a single laboratory using a standard solution of 600 µas CaCO3 and two representative lots of reagents with a DR/200single operator obtained a standard deviation of 3 µg/L.

DR/3000: In a single laboratory using a standard solution 520 µas CaCO3 and two representative lots of reagents with a DR/300single operator obtained a standard deviation of 4 µg/L.

InterferencesInterference studies were conducted at various hardness lebetween 0 and 500 µg/L as CaCO3. Various cations and anionswere evaluated at levels in the range appropriate to ultra pwater applications. An ion is said to interfere when the resultconcentration is changed by ±10%.

:

:

Summary of MethodCalcium and magnesium combine equivalently with tChlorophosphonazo Indicator to form a complex which absolight very strongly at 669 nm. One drop of the CDTA reagebreaks up this complex, and the resultant decrease in absorbis linearly related to the amount of calcium and magnesium CaCO3) in the sample.

Table 1 Negative Interference

Ion Level above which ion interferes (µg/L)

Aluminum 150

Sodium 79,000

Table 2 Positive Interference

Ion Level above which ion interferes (µg/L)

Copper 250

Silicon 1,000

Table 3 No Interference

Ion Highest Concentration Tested (µg/L)

Potassium 1,000

Ammonium 1,000

Formaldehyde 47,000

37


REQUIRED REAGENTSDescription Cat. No.Chlorophosphonazo Indicator Solution, 500 mL ........................................................................ 25895-49CDTA Reagent for Ultra Low Range Hardness, 10 mL............................................................. 25896-36

REQUIRED APPARATUSCylinder, graduated, 50 mL, poly, each,........................................................................................ 1081-41Dispenser, Fixed-volume, 2.0 mL, Repipet Jr., each ................................................................... 22307-01Flask, Erlenmeyer, PMP w/cap, 125 mL, each............................................................................ 20898-43Pour-Thru Cell Assembly, DR/2000, Kit, each ........................................................................... 45215-00Pour-Thru Cell Assembly, DR/3000, Kit, each ........................................................................... 19941-00

OPTIONAL REAGENTSCalcium Standard Solution, 20 mg/L as CaCO3, 946 mL.......................................................... 21246-16Calcium Standard Solution, 0.50 mg/L as CaCO3, 946 mL........................................................ 20580-16Water, Ultra-pure (aldehyde-free), 500 mL................................................................................. 25946-49

OPTIONAL APPARATUSBeaker, poly, 50 mL....................................................................................................................... 1080-41Bottle, wash, 125 mL, each ......................................................................................................... 21901-43Cylinder, graduated, 25 mL, poly, each......................................................................................... 1081-40Flask, Erlenmeyer, PMP w/cap, 125 mL, 6/pkg.......................................................................... 20898-73Pipet, TenSette, 0.1 to 1.0 mL, each ............................................................................................ 19700-01Pipet Tips, for 19700-01 TenSette Pipet, 50/pkg........................................................................ 21856-96

Instrument SetupFor DR/2000s with software versions less than 3.0

The calibration program for this method cannot be installed in DR/2000s with software versions before 3.0. The followingmodifications to the procedure are necessary for these earliersoftware versions.

a) In place of Step 1, press 0 at the METHOD #? prompt,then press READ/ENTER to place the instrument in theabsorbance mode. The display will show: Abs

b) Follow the instructions of Step 2.

c) Follow the instructions of Step 3. The display will instead show: ZERO SAMPLE

d) Follow the instructions of Steps 4 through 8.

38

1.

asand

2.


Before proceeding to Step 9, pour approximately 25 mL ofadditional sample into the Pour-Thru cell.

Press: ZERO. The display will show: WAIT then: 0.000 Abs

e) Follow the instructions for Steps 9 and 10

f) In place of Step 11, press: READ/ENTER

The display will show: WAITthen the absorbance value will be displayed.

If the amount of hardness in this sample is within the range of themethod (0 to 1,000 µg/L as CaCO3), the absorbance valuedisplayed will be between 0.500 Abs and 2.500 Abs.

For example, the display may show an absorbance value of: 1.273

Record the displayed value. This value will be referred to as Abs

g) Follow the instructions of the remaining steps (12 through 14).

However, after completing Step 14, the display will not show µg/LCaCO3. It will show an absorbance value between 0.500 Abs 1.000 Abs.

For example, the display may show an absorbance value of: 0.786

Record the displayed value. This value will be referred to as Abs

h) To calculate total hardness as CaCO3, subtract Abs2 from Abs1and multiply the result by the slope factor 759 µg/L/Abs.

For example, if Abs1 = 1.273 and Abs2 = 0.786 then:µg/L as CaCO3 = (1.273 Abs - 0.786 Abs) x 759 µg/L/Abs = 370 µg/L as CaCO3

For DR/2000s with software versions 3.0 or greater1. Turn the instrument on and press SHIFT METHOD to enter

configuration mode. The display will show: MOMENTARY orCONSTANT ON

2. Press the UP ARROW key twice to select HACH UPDATE. Press READ/ENTER.

39

The display will show: ENTER #:

3. Press 2 2 7. Press READ/ENTER. The display will show: P227 ENTER nm

Note: If you make an error, press SHIFT CLEAR and re-enter the number. When the number is correct, press READ/ENTER.

4. Press: 6 6 9Press READ/ENTER. The display will show: P227 DECIMAL? 00.00

5. For this method, press the DOWN ARROW key twice to correctly position the decimal point. The display will show: P227 Decimal? 0000.

6. Press READ/ENTER when the decimal is correct. The display will show: P227 UNITS?

7. For this method, press the DOWN ARROW key three times to select the unit of measure. The display will show: P227 µg/l

8. Press READ/ENTER. The display will show: P227 µg/l __

9. Construct the correct symbol display: as CaCO3

a) Select the correct character symbol by scrolling with thearrow keys.

b) To make a letter upper case, press the SHIFT key.

c) To make a number subscript or regular, press SHIFT untilthe symbol is correct.

d) Make a space by pressing the DOWN ARROW key once.

e) Make sure you enter the display line exactly as shown,including spaces. Do not enter trailing spaces.


g) To end symbol entry, press READ/ENTER a second timeafter accepting the last character.


40

10. After accepting the symbol, the display will show: P227 TIMER?

11. This method has no timing periods, so press READ/ENTER. The display will show: #0 STANDARD

12. Press READ/ENTER to display the zero data pair. The display will show: 0.000 Abs 0000. µg/l

13. Press READ/ENTER. The display will show: # 1 STANDARD

14. Press READ/ENTER. The display will prompt for entry of the first concentration point: # 1 0000. µg/l

15. Enter concentration point #1 from the table below (Step 20) by pressing 1 0 0 0 so the display shows: # 1 1000. µg/l

16. Press READ/ENTER. The display will prompt for entry of the first absorbance point: # 1 0.000 Abs

17. Press SHIFT - to set the negative sign for the bleaching chemistry. Then enter the absorbance point #1 from the table below by pressing 1 3 1 8 so the display shows: # 1 -1.318 Abs

18. Press READ/ENTER. The display should show the first data pair:-1.318 Abs 1000. µg/l

19. Press READ/ENTER to accept the first data pair. The display will show: # 2 STANDARD

20. The data pair values from the table below are now entered.

21. Press SHIFT READ/ENTER to complete data point entry. The display will show: #:

22. Enter the validation number 3 7 9 1 so the display shows: #: 3791

Standard Concentration Absorbance

# 0 0 µg/l 0.000 Abs

# 1 1000 µg/l -1.318 Abs


41


23. Press READ/ENTER. The display should show: COMPLETED then: P227 µg/l as CaCO3

If the display shows INCORRECT # then prompts again for thevalidation number, you may have made a mistake during dataentry. Make sure the validation number is correct. If it is, the erroroccurred during some other part of the method entry. Press METHand respond to the ABORT? message by pressing READ/ENTER.Then re-enter the method.

After correct entry, the instrument is ready for use with method 227.

42

Method 8147

IRON (0 TO 1.300 mg/L)FerroZine Rapid Liquid Method*

For DR/2000 and DR/3000 Instruments For boiler, cooling, and natural waters

* Adapted from Stookey, L.L., Anal. Chem., 42 (7) 779 1970

1. Enter the stored program number for total iron (Fe), FerroZine method.

Press:

2 6 0 READ/ENTER


DIAL nm to 562


Instruments with software versions 3.0 and greater will not display the “DIAL nm to” message if the wavelength is already set correctly. The display will show the message in Step 3. Proceed with Step 4.

Note: For the DR/3000:Press: 27 Stored Programthe display will show:562.0


562 nm

Note: For the DR/3000, set the wavelength to 562.0 nm and press Clear.

Note: If samples cannot be analyzed immediately, see Sampling and Storage, below. Adjust pH of stored samples before analysis.

Note: Total iron determinations need a prior digestion; use any of the three digestion procedures given in Section I of the DR/2000 procedure manual.



mg/l Fe FZ


Note: Pre-clean the Pour-Thru Cell and all labware as specified in the AnalysisLabware portion of this procedure.

Note: Make sure the windows of the Pour-Thru Cell face side-to side in theDR/2000 and front-to-back in the DR/2000.

562 nm

43

IRON, continued

5. Rinse two clean 125-mL plastic Erlenmeyer flasks three times with the sample.

6. Rinse a clean 50-mL plastic graduated cylinder three times with the sample.

7. Fill this rinsed cylinder to the 50mL mark with sample.

8. Pour the contents of the 50-mL cylinder into one of the flasks. Measure a second 50-mL portion of sample into the graduated cylinder and pour the contents into the second flask.

44

IRON, continued

9. Add 1.0 mL of FerroZine Iron Reagent Solution to one of the flasks using the Repipet Dispenser. Swirl to mix. The remaining flask will be used as the blank.

Note: Crystals may form in the FerroZine Reagent when stored at cold temperatures. If this occurs, place the bottle in warm water to dissolve the crystals.

Note: If the sample contains rust, see Interferences below.

Note: For proof of accuracy, use a 0.4 mg/L iron standard solution (preparation given in Accuracy Check) in place of the sample.

10.Press: SHIFT TIMER

A five-minute reaction period will begin.

Note: A violet color will develop if iron is present.

Note: For the DR/3000, Press: 5 Timer

11.When the timer beeps, the display will show:

mg/l Fe FZ

Pour the contents of the flask containing the blank into the Pour-Thru Cell.


ZERO


WAIT

then:

0.000 mg/l Fe FZ

Note: For the DR/3000, Press: Zero Conc

45

Analysis Labware All containers used in this test must be cleaned thoroughly toremove any traces of iron. Rinse labware and the Pour-Thru Cellwith a 1:1 HCl solution or with a 1:25 dilution of FerroZineReagent. Rinse several times with deionized water.

Keep flasks tightly closed when not in use. Dedicate thesecontainers for iron analysis only. If containers are rinsed andcapped after each use, only occasional treatment with HCl orFerroZine is necessary.

Cleaning the Pour-thru CellThe Pour-Thru Cell may accumulate a buildup of colored products,especially if the reacted solutions are allowed to stand in the cell forlong periods after measurement. Remove the color by rinsing witha 1:1 dilution of HCl, followed by several demineralized waterrinses. Cover the glass funnel when it is not in use.

13.Pour the contents of the flask containing the prepared sample into the Pour-Thru Cell.

14. After the flow has stopped, press:

READ/ENTER


WAIT

then the result in mg/L iron will be displayed.


15.Flush the Pour-Thru Cell with 50 mL of demineralized water.


IRON, continued

46

ron.

Sampling and StorageCollect samples in acid-washed glass or plastic bottles. Topreserve samples, adjust the sample pH to 2 or less with nitricacid (about 2 mL per liter). Samples preserved in this manner canbe stored up to six months at room temperature. If only dissolvediron is to be reported, filter sample immediately after collectionand before addition of nitric acid.

Before testing, adjust the sample pH to 3 to 5 with ammoniumhydroxide, ACS. Do not exceed pH 5 as iron may precipitate.Correct test results for volume additions; see Correction forVolume Additions in Section I of the DR/2000 or DR/3000Procedures Manual for more detailed information.


a) Snap the neck off an Iron Voluette Ampule Standard, 25mg/L Fe.

b) Use the TenSette pipet to add 0.2, 0.4, and 0.6 mL ofstandard to three 50 mL samples, respectively.

c) Analyze each sample as described above. The ironconcentration should increase 0.1 mg/L for each 0.2 mL of25 mg/L standard added.

d) If these increases do not occur, see Standard Additions inSection I of the DR/2000 or DR/3000 Procedures Manualfor more information.

Standard Solution MethodPrepare a 0.4 mg/L iron working solution as follows:

a) Pipet 1.00 mL of iron standard solution, 100 mg/L Fe, intoa 250 mL volumetric flask.

b) Dilute to volume with demineralized water. Prepare thissolution daily. Analyze the working solution according tothe above procedure.

PrecisionDR/2000: In a single laboratory, using standard solutions of 0.500mg/L Fe and two representative lots of reagent with the DR/2000, asingle operator obtained a standard deviation of ±0.0027 mg/L i

IRON, continued

47

n.

inedsested

thesed

ing

inen ared be

es,

yer

irl

to a

nseed

DR/3000: In a single laboratory, using a standard solution of 0.80mg/L iron and two representative lots of reagent with the DR/3000, asingle operator obtained a standard deviation of ±0.002 mg/L iro

InterferencesCopper and cobalt may interfere to give slightly high results.

Strong chelates such as EDTA will interfere in the FerroZmethod for determining iron. The FerroVer or TPTZ methoshould be used for these samples. The TPTZ method is suggfor low concentrations.

Any of the three digestions given in the Digestion section of DR/2000 or DR/3000 Procedures Manual (Section I) can be uin place of the treatments given below to eliminate the followinterferences.

If rust or hydroxides are present, the sample, with the FerroZIron Reagent from Step 9, should be boiled for one minute iboiling water bath, then cooled to 24 °C (75 °F) befoproceeding with Step 10. The reduced sample volume shoulreturned to 50 mL with demineralized water.

If the sample contains magnetite (black iron oxide) or ferritperform the following procedure.

a) Fill a 50-mL graduated cylinder with 50 mL of sample.

b) Transfer the sample into a clean glass 125-mL Erlenmeflask.

c) Add 1.0-mL of FerroZine Iron Reagent Solution and swto mix.

d) Place the flask on a hot plate or over a flame and bring boil.

e) Continue boiling gently for 20 to 30 minutes.

Note: Do not allow to boil dry.

f) Return the boiled sample to the graduated cylinder. Rithe Erlenmeyer flask with small amounts of demineralizwater and empty into the graduated cylinder.

Note: A purple color will develop if iron is present.

IRON, continued

48

IRON, continued

g) Return the sample volume to the 50-mL mark withdemineralized water.

h) Pour the solution into a 125-mL Erlenmeyer flask andswirl to mix.

i) Proceed with Steps 10 through 14.

Summary of MethodThe FerroZine Iron Reagent forms a purple colored complex withtrace amounts of iron in samples that are buffered to a pH of 3.5.This method is applicable for determining trace levels of iron inchemical reagents and glycols and can be used to analyze samplescontaining magnetite (black iron oxide) or ferrites.

49

IRON, continued

REQUIRED REAGENTS AND APPARATUSDescription Cat. No. Cylinder, graduated, 50 mL, poly, each......................................................................................... 1081-41Dispenser, Fixed Volume, 1.0 mL, Repipet Jr., each................................................................... 21113-01FerroZine Iron Reagent Solution, 500 mL .................................................................................... 2301-49Flask, Erlenmeyer, PMP w/cap, 125 mL, each, (two required)................................................... 20898-43Pour-Thru Cell Assembly Kit, DR/2000, each............................................................................ 45215-00Pour-Thru Cell Assembly Kit, DR/3000, each............................................................................ 19941-00

OPTIONAL REAGENTSAmmonium Hydroxide, ACS, 500 mL ........................................................................................... 106-49Hydrochloric Acid Solution, 1:1 (6N), 500 mL .............................................................................. 884-49FerroZine Iron Reagent Solution, 1000 mL .................................................................................. 2301-53Iron Standard Solution, 100 mg/L Fe, 100 mL ........................................................................... 14175-42Iron Standard Solution, Voluette ampule, 25 mg/L Fe, 10 mL, 16/pkg ...................................... 14253-10Nitric Acid, ACS, 500 mL............................................................................................................... 152-49Nitric Acid Solution, 1:1, 500 mL................................................................................................. 2540-49Water, demineralized, 4 L................................................................................................................ 272-56

OPTIONAL APPARATUSAmpule Breaker Kit, each ........................................................................................................... 21968-00Beaker, poly, 50 mL, each ............................................................................................................. 1080-41Bottle, wash, 125 mL, each ......................................................................................................... 21901-43Dropper, calibrated, 0.5-mL & 1.0-mL mark, 6/pkg ................................................................... 23185-06Flask, Erlenmeyer, 125 mL, PMP w/cap, 6/pkg.......................................................................... 20898-73Flask, Erlenmeyer, 125 mL, each .................................................................................................... 505-43Flask, Erlenmeyer, 50 mL, each ...................................................................................................... 505-41Flask, volumetric, 250 mL, Class A, each................................................................................... 14574-46Hot plate, 3 1/2 inch diameter, 120 Vac, each ............................................................................. 12067-01Hot plate, 3 1/2 inch diameter, 240 Vac, each ............................................................................. 12067-02pH Indicator Paper, 1 to 11 pH, 5 rolls/pkg..................................................................................... 391-33pH Meter, EC10, portable, each .................................................................................................. 50050-00Pipet, serological, 2 mL, each ......................................................................................................... 532-36Pipet, TenSette, 0.1 to 1.0 mL, each ............................................................................................ 19700-01Pipet Tips, for 19700-01 TenSette Pipet, 50/pkg......................................................................... 21856-96Pipet, volumetric, Class A, 1.00 mL, each .................................................................................. 14515-35Pipet Filler, safety bulb, each ...................................................................................................... 14651-00Thermometer, -20 to 105 °C, each ................................................................................................ 1877-01

50

Method 10057

NITRITE, LOW RANGE 0 to 250 µg/L NO2--NDiazotization Rapid Liquid Method*

For DR/2000 and DR/3000 Instruments For aquaculture, treated, and natural waters

* Adapted from Standard Methods for the Examination of Water and Wastewater.

1. Enter the stored program number for low range nitrite nitrogen (NO2--N).

Press: 3 7 6 READ/ENTER


DIAL nm to 543


Note: Instruments with software versions 3.0 and greater will not display “DIAL nm to” message if the wavelength is already set correctly. The display will show the message in step 3. Proceed with step 4.

Note: If the sample cannot be analyzed immediately, see Sampling and Storage.

Note: For instruments that do not have this program, refer to Instrument Setup.

Note: For DR/3000s:Press: MANUAL PROGRAMPress: 151.1 CONC FACTOR

2. Rotate the wavelength dial until the display shows:

543 nm

Note: For DR/3000s, set the wavelength to 543.0 nm.


The display will show

µg/l N NO2- LRRL

Note: For DR/3000s,Press: 5 Signal AveragePress: ZeroPress: 0 Conc


Note: Pre-clean the Pour-Thru Cell and all labware as specified in Analysis Labware.

Note: Make sure the windows of the Pour-Thru Cell face side-to-side in the DR/2000 and front-to-back in the DR/3000.

543 nm

51

NITRITE, LR, continued

5. Rinse two clean 125-mL plastic Erlenmeyer flasks three times with the sample to be tested.

Note: For proof of accuracy, use a 100 µg/L nitrite nitrogen standard solution (preparation given in Accuracy Check) in place of the sample.

6. Rinse a clean 25-mL plastic graduated cylinder three times with sample.

7. Fill this rinsed cylinder to the 25-mL mark with sample.

8. Pour the contents of the 25-mL cylinder into one of the flasks. Measure a second 25-mL portion of sample into the graduated cylinder and pour the contents into the second flask.

9. Add 1.0 mL of prepared Nitrite Reagent Solution to one of the flasks using the Repipet Dispenser. Swirl to mix. (The other flask will be used as the blank.)

Note: See Reagent Preparation for instructions on preparing the Nitrite Reagent and information regarding reagent discoloration.

10.Press: SHIFT TIMER

A ten-minute reaction period will begin.

Note: For DR/3000s, Press: 10 Timer

11.When the timer beeps, the display will show:

µg/l N NO2- LRRL

Pour the contents of the flask containing the blank into the Pour-Thru Cell.


ZERO


WAIT

then:

0 µg/l N NO2- LRRL

Note: For DR/3000s, Press: Zero Conc

52


13.Pour the contents of the flask containing the prepared sample into the Pour-Thru Cell.

14.PressREAD/ENTER


WAIT

then the result in µg/L nitrite expressed as nitrogen (NO2--N) will be displayed.


Note: Express the results as µg/L nitrite (NO2

-) by multiplying the µg/L nitrite nitrogen (NO2

--N) by 3.3.

Note: A reagent blank should be obtained when the nitrite concentration is less than 60 µg/L. Use demineralized water in place of the sample in steps 5-14. Subtract this value from that of the sample.



53

offterent.

anks

hly.ngwithn ofwellhisingitenly


Reagent PreparationThe Nitrite Reagent Solution must be prepared by the user as follows: Using a powder funnel, add the contents of one Nitrite IndicatorPowder Pillow (Cat. No. 26209-64) to one 236-mL bottle of NitriteDiluent Solution (Cat. No. 26208-31). The powder dissolves slowly,therefore the solution should be mixed by inverting the bottlecontinuously for 10 - 15 minutes. Alternatively, a magnetic stirrermay be used for mixing after adding a clean stir bar to the solution. Ifpowder is still visible in the solution after this time, continue to mixuntil the powder is dissolved.

This solution will develop a brownish-purple color with time but willstill give accurate results for two weeks after mixing when stored at20-25 °C and away from direct sunlight. Record the datepreparation on the bottle and discard any remaining solution atwo weeks. Do not add fresh reagent to previously mixed reagUse of this reagent after 2 weeks may result in high reagent bland low values at high concentrations.

Analysis LabwareAll containers used in this test must be cleaned thorougPlastic flasks with screw-type closures work well for sampliand analysis. Clean containers by normal means, then rinse demineralized water. Soak labware for 10 minutes in a solutio1 mL prepared reagent to 25 mL demineralized water. Rinse with demineralized water. Pre-treat the Pour-Thru Cell with tsame mixture of reagent and water followed by thorough rinswith demineralized water. Dedicate labware used for nitranalysis only. If the labware is rinsed well after each use, ooccasional pre-treatment is necessary.

Sampling and StorageCollect samples in clean plastic or glass bottles.

54

edingric

le

to

93e

redion00is

L/L

of, a9%

of, a9%

ionsad,sing


Note: If mercuric chloride is used, collect the spent sample for proper disposal according to the hazardous waste regulations for mercury. Refer to the DR/2000 or DR/3000 Instrument Manual for information on modifying the Pour-Thru Cell for collecting samples after analysis.

Store at 4 °C (30 °F) or lower if the sample is to be analyzwithin 24 to 48 hours. Warm to room temperature before runnthe test. For longer storage periods, add 4.0 mL of MercuChloride Solution* per liter of sample and mix. Samprefrigeration is still required. Do not use acid preservatives.

*Use of mercuric chloride is not recommended due environmental and health concerns.

Accuracy CheckStandard Solution Method

Prepare a nitrite nitrogen stock solution by dissolving 0.4grams of sodium nitrite, ACS, in 1000 mL of nitrite-fredemineralized water to give a 100 mg/L nitrite nitrogen (NO2--N)stock solution. This solution is not stable and should be prepadaily. Use a Class A pipet to dilute 1.00 mL of the stock solutto 1000 mL with nitrite-free demineralized water to give a 1µg/L (NO2--N) nitrite nitrogen standard solution. Prepare thsolution immediately before use.

This solution can also be prepared by diluting 5.00 mL of a 250 mg/L NO2--N stock solution to 250 mL to give a 5000 µg/intermediate standard. Dilute 10.00 mL of the 5000 µgintermediate to 500 mL to give a 100 µg/L NO2--N standard.

PrecisionDR/2000: In a single laboratory using seven concentrationsnitrite standards and two lots of reagent with the DR/2000single operator obtained a calibration curve that showed a 9confidence interval at 100 µg/L of less than 1 µg/L.

DR/3000: In a single laboratory using seven concentrationsnitrite standards and two lots of reagent with the DR/3000single operator obtained a calibration curve that showed a 9confidence interval at 100 µg/L of less than 1 µg/L.

InterferencesStrong oxidizing and reducing substances interfere. Ferrous cause low results. Mercuric, silver, bismuth, antimonous, leauric, chloroplatinate and metavanadate ions interfere by cauprecipitation.

55

Very high levels of nitrate (100 mg/L nitrate as N or more) appearto undergo a slight amount of reduction to nitrite, eitherspontaneously or during the course of the test. A small amount ofnitrite will be found at these levels. Ammonia below 50 mg/L asNH3-N does not interfere.

The following ions do not interfere at concentrations lower thanthose given:

Remove suspended solids by filtration.

Summary of MethodNitrite in the sample reacts with sulfanilamide to form anintermediate diazonium salt. This couples with N-(1-napthyl)-ethylenediamine dihydrochloride to produce a red-coloredcomplex directly proportional to the amount of nitrite present.

Al3+ 1 mg/LZn2+ 0.2 mg/L

Ca2+ as CaCO3 1000 mg/LNi2+ 2.5 mg/LCu2+ 5 mg/L

Fe3+ 5 mg/L


56

REQUIRED REAGENTSDescription Cat. No.Nitrite Reagent Package .............................................................................................................. 26612-00Includes:Nitrite Indicator Powder Pillows, 4/pkg...................................................................................... 26209-64Nitrite Diluent Solution, 236 mL, 4 each .................................................................................... 26208-31

REQUIRED APPARATUSClippers, for opening powder pillows ............................................................................................. 968-00Cylinder, graduated, 25 mL, poly, each......................................................................................... 1081-40Dispenser, Fixed Volume, 1.0 mL Repipet Jr., each ................................................................... 21113-01Flask, Erlenmeyer, 125 mL PMP w/cap, each (two required) .................................................... 20898-43Pour-Thru Cell Assembly Kit, DR/2000, each............................................................................ 45215-00Pour-Thru Cell Assembly Kit, DR/3000, each............................................................................ 19941-00

OPTIONAL REAGENTSMercuric Chloride Solution, 10 g/L, 100 mL.............................................................................. 14994-42Nitrite Standard Solution, 250 mg/L as

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