DKS 2258:2010

KENYA STANDARD

Water for lead-acid batteries ─ Specification

©KEBS 2010 First Edition 2010

DKS 2258:2010

TECHNICAL COMMITTEE REPRESENTATION

The following organizations were represented on the Technical Committee:

Nayan Products Government Chemist Jet Chemicals Ltd. Automotive & Industrial Battery Manufacturers (K) ltd

Associated Battery Manufacturers (E A) Ltd KIRDI Lacheka Lubricants University of Nairobi Consumer Information Network Kenya Bureau of Standards — Secretariat

REVISION OF KENYA STANDARDS

In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed. Suggestions for improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are welcome.

© Kenya Bureau of Standards, 2010

Copyright. Users are reminded that by virtue of section 25 of the Copyright Act, Cap. 12 of 2001 of the Laws of Kenya, copyright subsists in all Kenya Standards and except as provided under section 26 of this Act, no Kenya Standard produced by Kenya Bureau of Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing from the Managing Director.

DKS 2258:2010

KENYA STANDARD

Water for lead-acid batteries ─ Specification

KENYA BUREAU OF STANDARDS (KEBS)

Head Office: P.O. Box 54974, Nairobi-00200, Tel.: (+254 020) 605490, 602350, Fax: (+254 020) 604031 E-Mail: info@kebs.org, Web:http://www.kebs.org

Coast Region Lake Region North Rift Regi on

P.O. Box 99376, Mombasa-80100 P.O. Box 2949, Kisumu-40100 P.O. Box 2138, Nakuru-20100 Tel.: (+254 041) 229563, 230939/40 Tel.: (+254 057) 23549, 22396 Tel.: (+254 051) 210553, 210555 Fax: (+254 041) 229448 Fax: (+254 057) 21814

DKS 2258:2010

Foreword

This Kenya standard was developed by the Technical Committee on Water Quality under the guidance of the Standards Projects Committee, and it is in accordance with the procedures of the Bureau. Two grades of water are specified. Grade A gives the requirements for distilled or deionized water which should preferably be used whenever it is available and should always be used for counter-EMF cells. The specification for grade B represents minimum grade of water that can be used in lead-acid batteries. In the preparation of this standard reference was made to the following publications: MS 994 Specification for Water for lead – acid batteries BS 4974 Specification for Water for lead – acid batteries Assistance obtained from this source is acknowledged.

DKS 2258:2010

KENYA STANDARD KS 2258:2010

Water for lead – acid batteries ─ Specification

1. SCOPE This Kenya Standard specifies requirements for two grades of water for lead-acid batteries. Grade A water is an all-purpose quality which should preferably be used. Grade B is the minimum quality of water which can be used in lead-acid batteries.

2. GRADE A WATER 2.1 Description The material shall be water purified by distillation or Ion exchange. It shall be clear and colour less when viewed through a depth of 300 mm. 2.2 Conductivity The material shall not have a conductivity greater than 10 micromhos per centimeter (µm ho/cm), measured at 20°C when tested by the method describe d in annex H. 2.3 Manganese content The material shall not contain more than 0.1 mg of manganese, Mn, per kilogramme, determined and calculated by the method described in annex A. 3. GRADE B WATER 3.1 Description The material shall be water free from matter in suspension and shall be colourless when viewed through a depth of 300 mm 3.2 The material shall comply with the requirements given in table 1.

Table 1 —Requirements for grade B water

SL. No

Characteristic Requirement Test method

1. Sulphated residue on ignition, mg per kilogramme, maximum

150 Annex B

2. Chloride content, expressed as Cl, mg per kilogramme, maximum

10 Annex C

3. Ammoniacal nitrogen content,

expressed as NH3, mg per

Kilogramme, maximum

10 Annex D

4. Nitrogen oxides content, expressed as N, mg per kilogramme maximum

3 Annex E

5. Iron content, Fe, mg per kilogramme, maximum

5 Annex F

6.

Copper content, Cu, per kilogramme, maximum

5

Annex G

DKS 2258:2010

7. Manganese content, Mn, per kilogramme, maximum

0.1 A

4.0 Sampling For the purpose of examination in accordance with this specification a representative sample of the material not less than 2000 ml in volume shall be taken from the bulk. The sample shall be placed in a clean dry and airtight glass-stoppered bottle of borosilicate glass of such a size that it is nearly filled by the sample. If it is necessary to seal the bottle, care shall be taken to avoid contaminating the contents in any way. 5.0 Packaging and marking 2.5.1 Packaging The material shall be supplied in sound, clean containers of glass, polyethylene or other suitable plastics material. 2.5.2 Marking

Each container and box or carton shall be marked legibly and indelibly with the following particulars: (i) Name and address of the manufacturer/supplier and registered trade mark if any. (ii) Product name (iii) Date of manufacture and best before date (iv) Batch number or lot number v) Net contents (vi) Number of containers contained in the package; vi) Country of origin

DKS 2258:2010

Annex A Determination of manganese content

A1. OUTLINE OF THE METHOD The manganese present is oxidized with potassium periodate and the permanganate formed is determined photometrically or, alternatively, by visual comparison. A2. APPARATUS (a) Photoelectric absorptiometer or spectrophotometer with 4 cm cells, alternatively, matched Nessler

cylinders. (b) Eight one-mark volumetric flasks, 100 ml capacity. A3. REAGENTS The reagents used shall be of a recognized analytical reagent quality. Water complying with the requirements of KS ISO 3696 shall be used throughout. a) Sulphuric acid, concentrated, 98 % (m/m) (36) (b) Oxidizing solution. Mix 250 ml of concentrated nitric acid 70 % (m/m) (16 N), 60 ml of orthophosphoric acid, 90 % (m/m) (48N), and 2.5 g of potassium periodate and dilute to 1000 ml with water. (c) Standard manganese solution. Place in a 400 ml beaker a volume of freshly standardized 0.1 N (0.02M) potassium permanganate solution calculated from the formula:

Dilute to about 150 ml and add 5 ml of the sulphuric acid (A3 (a)). Carefully add 10 g/I sodium metabisulphite solution, stirring constantly, until the solution is just decolorized. Heat to boiling and boil for 10 min. Cool, transfer to a 1000 ml one-mark volumetric flask and dilute to the mark with water. Further dilute 200 ml of this solution to 1000 ml. 1ml of this solution Ξ 10µg Mn. A.4 PROCEDURE

A4.1 Preparation of colour standards Into six 250 ml beakers transfer amounts of the standard manganese solution containing from 0 (blank) to 50µg of manganese, increasing by stages of 1 µg, and treat each solution in the following manner: Add 15 ml of the sulphuric acid, heat to boiling and evaporate until dense white fumes are evolved, reducing the volume to between 5 ml and 10 ml. Allow to cool, cautiously dilute to about 25 ml and add 70 ml of the oxidizing solution. Heat to boiling and boil the solution for 4 min, then cool rapidly to room temperature. Transfer the solution to a 100 ml one-mark volumetric flask and dilute to the mark with water. These colour standards are used directly for visual comparison. If an instrument is to be used, measure the absorbances of the solutions at a wavelength of 520 nm, using the blank as reference standard, and prepare a calibration chart. A4.2 Determination Transfer 200 ml of the sample to a 500 ml beaker, add 15 ml of the sulphuric acid, heat to boiling

DKS 2258:2010

and evaporate until dense white fumes are evolved, reducing the volume to between 5 ml and 10 ml. Allow to cool, cautiously dilute to about 25 ml and add 70 ml of the oxidizing solution. Heat to boiling and boil the solution for 4 min, then cool rapidly to room temperature. Transfer the solution to a 100 ml one-mark volumetric flask and dilute to the mark with water. At the same time carry out a blank test on the reagents alone. Measure the absorbance of the solution at a wavelength of 520 nm using the reagent blank as reference standard and read the amount of manganese present from the calibration chart (see A4. 1). Alternatively, compare the colour of the solution with the series of prepared colour standards in matched Nessler cylinders, noting the manganese content of the standard that most nearly matches the test solution. A5. CALCULATION Manganese content, expressed as milligrammes of manganese, Mn per kilogramme = 0.005 M1 where M1 = mass of manganese found (µg).

DKS 2258:2010

ANNEX B

DETERMINATION OF SULPHATED RESIDUE ON IGNITION

B.1 APPARATUS The following apparatus is required: Platinum dish, approximately 50mm diameter. B.2 REAGENT The reagent used shall be of recognized analytical reagent quality; Sulphuric acid, concentrated, 98 %( m/m) (36N) B.3 PROCEDURE Evaporate carefully, in small portions, 500 ml of the sample to small bulk in a pre-ignited weighed platinum dish. Add a few drops of concentrated sulphuric acid and evaporate to dryness in a fume cupboard until no further fumes are evolved. Finally ignite the residue to constant mass at 850 ± 50°C. B.4 CALCULATION Sulphated residue on ignition, in milligrammes per kilogramme = 2000 x M2 Where M2 = mass of residue found (g).

DKS 2258:2010

ANNEX C

DETERMINATION OF CHLORIDE CONTENT

C.1 OUTLINE OF THE METHOD The chloride present is determined nephelometrically using silver nitrate. C.2 APPARATUS The following apparatus is required:

a) Photoelectric absorptiometer with 4 cm cells. Alternatively matched Nessler cylinders. b) Fifteen one-mark volumetric flasks, 100 ml capacity.

C.3 REAGENTS The reagents used shall be of a recognized analytical reagent quality.

a) Nitric acid, concentrated, 70% (m/m) (16N) b) Silver nitrate, approximately 0.1 N solution c) Standard chloride solution. Dissolve 1.648 g of previously dried sodium chloride in water

and dilute to 1000 ml. Further dilute 10 ml of this solution to 1000 ml with water. 1 ml of the diluted solution ≡ 10 µg CI. C.4 PROCEDURE C4.1 Preparation of standard solutions Into thirteen 100 ml one-mark volumetric flasks each containing about 65 ml of water, transfer amounts of the standard chloride solution, containing from 0 (blank) to 120 µg increasing by stages of 10 µg of chloride, and treat each solution in the following manner: 'BS 612 , 1983, 'Nessler cylinder' Dilute to about 95 ml, add 1 ml of the nitric acid and 2 ml of the silver nitrate solution, dilute to the mark with water, mix well and allow to stand in the dark at room temperature for not less than 5 min and not more than 15 min. These solutions are used directly for visual comparison. If an instrument is to be used, measure the absorbances of the solutions in the absorptiometer using a neutral filter and, with the reagent blank as reference standard, prepare a calibration chart. C4.2 Determination Transfer 10 ml of the sample to a 100 ml one-mark volumetric flask and dilute to about 65 ml with water. Add 1 ml of the nitric acid and 2 ml of the silver nitrate solution, dilute to the mark with water, mix well and allow to stand in the dark at room temperature for not less than 5 min and not more than 15 min. At the same time carry out a blank on the reagents alone. Measure the absorbance of the solution in the absorptiometer using a neutral filter and, with the reagent blank as reference standard, read the amount of chloride present from the calibration chart (see C4.1). Alternatively, compare the turbidity of the solution with the series of prepared standard solutions in matched Nessler cylinders, noting the chloride content of the standard solution that most nearly matches the test solution. C.5 Calculation Chloride content, expressed as milligrammes of chlorine, CI, per kilogramme = 0.1 x M3.

DKS 2258:2010

where M3 = mass of chloride found (µg).

DKS 2258:2010

ANNEX D

DETERMINATION OF AMMONIACAL NITROGEN CONTENT

D.1 OUTLINE OF THE METHOD

Ammonia is distilled from the sample after the addition of sodium carbonate and is determined photometrically using Nessler's reagent or alternatively by visual comparison. D.2 APPARATUS The following apparatus is required; (a) Photoelectric absorptiometer or spectrophotometer with 4 cm cells. Alternatively, matched Nessler

cylinders. (b) Twelve one-mark volumetric flasks, 100 ml capacity. (c) All-glass distillation apparatus, with 1000 ml distillation flask. D.3 REAGENTS The reagents used shall be of a recognized analytical reagent quality. Water, purified if necessary to free it from ammonia, shall be used throughout. A satisfactory water can usually be obtained by shaking 5000 ml of distilled water with 10 g of a strong cation exchange resin in the hydrogen form or by passing water through a column of such resin. The water may also be prepared by distillation of tap water in all-glass apparatus after the addition of 1 ml of a 500 g/I sulphuric acid solution per litre. The distillate shall be tested with Nessler's reagent and when free from ammonia, shall be collected in a glass-stoppered bottle. a) Sodium carbonate, anhydrous (b) Nessler's reagent. Dissolve 3.5 g of potassium iodide and 1.25 g of mercury (II) chloride in 80 ml of water. Add a cold saturated aqueous solution of mercury (II) chloride, stirring constantly, until a slight red precipitate remains, then add 12 g of sodium hydroxide. Allow this to dissolve, add a little more of the saturated mercury (II) chloride solution until a slight turbidity is obtained, and dilute to 100 ml with water. Allow to settle, decant and store in the dark. (c) Standard ammonia solution. Dissolve 3.141 g of ammonium chloride in water and dilute to 1000 ml. Further dilute 10 ml of this solution to 1000 ml with water. 1 ml of the diluted solution ≡ 10 µg NH3.

D.4 PROCEDURE D.4.1 Preparation of colour standards

Into eleven of the 100 Ml one-mark volumetric flasks, each containing 60 ml of water,

transfer amounts of the standard ammonia solution containing from 0 (blank) to 100 µg of

ammonia, increasing by stages of 10 µg, and treat each solution in the following manner:

Dilute to about 95 ml, add 2 ml of the Nessler's reagent, dilute to the mark, mix thoroughly and allow to

stand for a period of 10 min to 15 min.

These colour standards are used directly for visual comparison. If an instrument is to be used, measure

the absorbances of the solutions at a wavelength of the 370 nm, using the reagent blank as reference

standard, and prepare a calibration chart.

D.4.2 Determination Transfer 50 ml of sample to the distillation flask, dilute to 500 ml with water and add 0.5 g of

DKS 2258:2010

sodium carbonate. Connect the flask to the distillation assembly, heat to boiling and collect 100 ml of distillate. Transfer a 20 ml aliquot portion to another 100 ml volumetric flask and dilute to about 95 ml. Add 2 ml of the Nessler's reagent, dilute to the mark, mix thoroughly and allow to stand for a period of 10 min to 15 min. At the same time, carry out a blank test using the reagents alone. Measure the absorbance of the solution at a wavelength of 370 nm, using the blank as reference standard, and read the amount of ammonia present from the calibration chart (see D.4.1).

Alternatively, compare the colour of the solution with the series of prepared colour standards in matched

Nessler cylinders, noting the ammonia content of the standard that most nearly matches the test solution.

Collect a further 100 ml of distillate and treat in the same way; no ammonia should be present in this

second portion of distillate.

D.5 CALCULATION Ammoniacal nitrogen content, expressed as milligrammes of ammonia, NH3, per kilogramme = 0.1 M4.

where M4 = mass of ammonia found in the aliquot portion of the sample taken (µg).

DKS 2258:2010

ANNEX E DETERMINATION OF NITROGEN OXIDES CONTENT

E.1 OUTLINE OF THE METHOD The nitrogen oxides present are first oxidized using potassium permanganate solution and then treated

with 2, 4-xylenol reagent. The resulting nitro-xylenol is distilled and the amount present in the distillate is

determined photometrically or alternatively by visual comparison.

E.2 APPARATUS The following apparatus is required;

a) Photoelectric absorptiometer or spectrophotometer with 4 cm cells, alternatively matched Nessler

cylinders. b) Water bath, capable of being controlled at 35 ± 10C,

c) Twelve one-mark volumetric flasks, 100 ml capacity.

d) All-glass distillation apparatus

E.3 REAGENTS

The reagents used shall be of a recognized analytical reagent quality.

a) Mercury (ii) acetate

b) Sulphuric acid, approximately 31 N solution. Add 400 ml of concentrated sulphuric acid, 98% (m/m)

(36N) (free of nitrogen), to 100 ml of water. To ensure complete elimination of nitrogen oxides, prepare the

concentrated sulphuric acid as follows: Cautiously add 450 ml of concentrated sulphuric acid to

approximately 110 ml of water and heat until white fumes are liberated, Cool; repeat the dilution and

heating twice,

c) Hydrogen peroxide, 1 g/l solution

d) 2, 4-xylenol, 10 m/l solution in glacial acetic acid, freshly prepared

e) Sodium hydroxide, approximately 2N solution

f) Sodium hydroxide, approximately 0.2N solution. Dilute 100 ml of the 2N sodium hydroxide solution

(see item (5) above) to 1000 ml with water.

g) Potassium permanganate, 0.1 N solution

h) Standard nitrogen solution. Dissolve 0.3609 g of potassium nitrate in water and dilute to 100 ml.

1 ml of the solution ≡ 500 µg N.

E.4 PROCEDURE

E4.1 Preparation of standard distillate

To 9 ml of water contained in a small flask carefully add 30 ml of the sulphuric acid solution. Cool to

35°C, then pour the diluted acid into a 100 ml grou nd glass stoppered boiling tube containing

DKS 2258:2010

1.00 ml of the standard nitrogen solution.

Add 1 ml of the 2, 4-xylenol reagent and mix well. Transfer the tube to the water bath and maintain at 35 ± 1°C for 30 min. At the end of this period, remove from the bath and transfer the contents of the tube completely to the distillation flask and dilute with 100 ml of water. Connect the flask to the distillation assembly, heat to boiling and collect approximately 60 ml of the distillate in a 100 ml one-mark volumetric flask containing 10 ml of the 2N sodium hydroxide solution. Cut the water supply to the condenser towards the end of the distillation so as to ensure that no nitrated 2, 4-xylenol remains in the condenser. Dilute to the mark with water and mix thoroughly. E4.2 Preparation of colour standards Into ten of the 100 ml one-mark volumetric flasks, transfer amounts of from 1 ml to 10 ml of the distillate, increasing in stages of 1 ml, corresponding to nitrogen contents from 5 µg to 50 µg. Dilute each solution to the mark with the 0.2N sodium hydroxide solution and mix thoroughly. These colour standards are used directly for visual comparison. If an instrument is used, measure the absorbances of the solution at a wavelength of 445 nm, using the 0.2 N sodium hydroxide solution as reference standard, and prepare a calibration chart. E4.3 Determination Transfer 10 ml of the sample to a 100 ml ground glass stoppered boiling tube. Add 2 or 3 drops of the potassium permanganate solution and 0.5 ml of the sulphuric acid solution drop by drop from a burette, shaking the tube during the addition. Then add the hydrogen peroxide solution, drop by drop. until the permanganate colour is just discharged. Immerse the tube in ice water and. when cold, add a further 29.5 ml of the sulphuric acid solution drop by drop, mixing continuously, keeping the temperature below 40°C during this addition. Add 0.2 g of the mercury (II) acetate and. when dissolved, add 1 ml of the 2, 4-xylenol reagent, mix well and immerse the tube in the water bath, controlled at 35 ± 0.1 °C , for 30 min. At the end of this period remove from the bath, transfer the contents of the tube completely to the distillation flask, and dilute with 100 ml of water. Connect the flask to the distillation assembly, heat to boiling and collect approximately 60 ml of the distillate in a 100 ml one-mark volumetric flask containing 10 ml of the 2N sodium hydroxide solution. Cut the water supply to the condenser towards the end of the distillation so as to ensure that no nitrated 2,4-xylenol remains in the condenser. Dilute to the mark with water and mix thoroughly. Carry out a blank test on 30 ml of the sulphuric acid solution E3(6), adding it drop by drop to 10 ml of water contained in a 100 ml ground glass stoppered boiling tube immersed in ice water, keeping the temperature below 40°C during the addition. Continu e the procedure as from the second paragraph of E4.3. Measure the absorbances of the test solution and of the blank solution at a wavelength of 445 nm, using the 0.2N sodium hydroxide solution as reference standard. Subtract the absorbance of the blank from that of the test solution and read the amount of nitrogen present from the calibration chart (see E4.2). Alternatively, compare the colours of the test and blank solutions with the series of prepared colour standards in matched Nessler cylinders. Note the nitrogen contents of the matching standards and determine the nitrogen content of the sample by difference.

DKS 2258:2010

E.5 CALCULATION Nitrogen oxides content, expressed as milligrammes of nitrogen, N, per kilogramme = 0.1 M5, where M5 = mass of nitrogen found (µg).

DKS 2258:2010

ANNEX F DETERMINATION OF IRON CONTENT

F.1 OUTLINE OF THE METHOD The iron present is reduced to the iron (II) state and determined photometrically using 2, 2'-bipyridyl or alternatively by visual comparison. F.2 APPARATUS The following apparatus is required; (a) Photoelectric absorptiometer or spectrophotometer with 4 cm cells. Alternatively, matched Nessler

cylinders. (b) Thirteen one-mark volumetric flasks, 100 ml capacity. (c) One mark volumetric flask, 250 ml capacity. F.3 REAGENTS The reagents used shall be of a recognized analytical reagent quality.

a) hydrochloric acid, approximately N solution b) hydroxyl ammoniumchloride, 50 g/l solution c) ammonium acetate, 400g/l solution d) 2, 2'-bipyridyl, 1 g/I solution. Dissolve 0.1 g of the reagent in 50 ml of water containing 2 ml of the

N hydrochloric acid solution and dilute to 100 ml e) Standard iron solution. Dissolve 7.022 g of ammonium iron (II) sulphate in a mixture of 600 ml of

water and 350 ml of concentrated sulphuric acid, 98% (m/m) (36N), and dilute to 100 ml with water. Further dilute 10 ml of the solution so obtained to 1000 ml with water.

1 ml of the diluted solution ≡ µg Fe. F.4 PROCEDURE F4.1 Preparation of colour standards Into eleven of the 100 ml one-mark volumetric flasks, each containing 50 ml of water and 2 ml of the N hydrochloric acid solution, transfer amounts of the standard iron solution, containing from 0 (blank) to 100 µg of iron, increasing by stages of 10 µg and treat each solution in the following manner: Add 4 ml of the hydroxylammonium chloride solution and allow to stand for 1 min. Add 5 ml of the ammonium acetate solution and 3 ml of the 2, 2'-bipyridyl solution. Dilute the contents of each flask to 100 ml and mix thoroughly. These colour standards are used directly for visual comparison. If an instrument is to be used, measure the absorbances of the solutions at a wavelength of 51 5 nm, using the reagent blank as reference standard, and prepare a calibration chart. F4.2 Determination Transfer 10 ml of the sample to a 100 ml one-mark volumetric flask. Add 2 ml of the N hydrochloric acid solution, 4 ml of the hydroxylammonium chloride solution, and allow to stand for 1 min. Add 5 ml of the ammonium acetate solution, mix and add 3 ml of the 2, 2'-bipyridyl solution. Dilute to 100 ml with water and mix thoroughly. Measure the absorbance of the solution at a wavelength of 51 5 nm, using the reagent blank as reference standard, and read the amount of iron present from the calibration chart (see F4.1). Alternatively, compare the colour of the solution with the series of prepared colour standards in matched

DKS 2258:2010

Nessler cylinders, noting the iron content of the standard that most nearly matches the test solution. F.5 CALCULATION Iron content, expressed as milligrammes of iron, Fe, per kilogramme = 0.1 M6 , where M6 = mass of iron found (µg)

DKS 2258:2010

ANNEX G DETERMINATION OF COPPER CONTENT

G.1 OUTLINE OF THE METHOD The copper present is reduced with ascorbic acid and a violet coloured complex is formed by addition of 2, 2' biquinolyl. This complex is extracted with amyl alcohol and measured photometrically or alternatively by visual comparison. G.2 APPARATUS The following apparatus is required; (a) Photoelectric absorptiometer or spectrophotometer with 4 cm cells. Alternatively, matched Nessler

cylinders. (b) Eight one-mark volumetric flasks, 50 ml, capacity

G.3 REAGENTS The reagents used shall be of a recognized analytical reagent quality.

(a) Sodium sulphate, anhydrous.

(b) Amyl alcohol.

(c) Hydrochloric acid, N solution.

(d) Hydrochloric acid, concentrated, 36% (m/m) (11 N).

(e) Tartaric acid, 500 g/I aqueous solution. (f) Sodium hydroxide, 5 N aqueous solution.

(g) Ascorbic acid, 100 g/I aqueous solution, freshly prepared.

(h) 2, 2'-biquinolyl, 0.5 g/I solution in amyl alcohol. (j) Standard copper solution, Dissolve 0.3928 g of copper (II) sulphate pentahydrate in water, add 25 ml of 6N sulphuric acid solution, add dilute to 1000 ml. Further dilute 10 ml of the solution to 100 ml.

1 ml of the diluted solution ≡ 1 0 µg Cu.

(k) Narrow range indicator papers, covering the range pH 5.5 to pH 7.0.

G.4 PROCEDURE

G4.1 Preparation of colour standards Into six 100 ml beakers transfer amounts of the standard copper solution containing from 0 (blank) to 100 µg of copper, increasing by stages of 20 µg, and treat each solution in the following manner: Dilute to approximately 30 ml with water and transfer to a 500 ml stoppered separating funnel. Dilute with water to approximately 400 ml and add 2 ml of the tartaric acid solution. Adjust the pH of the solution to approximately 6.0 by addition of the sodium hydroxide solution, using a narrow range indicator paper externally. Add 2 ml of the ascorbic acid solution, shake to mix thoroughly and allow to stand for 5 min. Add 10 ml of the 2,2'-biquinolyl solution and shake well for about 2 min. Extract the copper complex with two 20 ml portions of amyl alcohol and transfer the extracts to a 100 ml beaker. Add about 2 g of the anhydrous sodium sulphate to the combined extracts and stir thoroughly to remove traces of water. Filter into a 50 Ml one-mark volumetric flask and wash the sodium sulphate crystals twice with 2 ml portions of amyl alcohol. Transfer the washings to the flask and dilute to the mark with amyl alcohol. These colour standards are used directly for visual comparison. If an instrument is to be used, measure the absorbances of the solutions at a wavelength of 545 nm, using the reagent blank as reference standard, and prepare a calibration chart.

DKS 2258:2010

G4.2 Determination Transfer 10 ml of the sample to a 500 ml stoppered separating funnel. Add 1 ml of the concentrated hydrochloric acid, dilute to 400 ml with water and add 2 ml of the tartaric acid solution. Adjust the pH of the solution to approximately 6.0 by addition of the sodium hydroxide solution, using a narrow range indicator paper externally. Add 2 ml of the ascorbic acid solution, shake to mix thoroughly and allow to stand for 5 min. Add 10 ml of the 2,2'-biquinolyl solution and shake well for about 2 min. Extract the copper complex with two 20 ml portions of amyl alcohol and transfer the extracts to a 100 ml beaker. Add about 2 g of the anhydrous sodium sulphate to the combined extracts and stir thoroughly to remove traces of water. Filter into a 50 ml one-mark volumetric flask and wash the sodium sulphate crystals twice with 2 ml portions of amyl alcohol. Transfer the washings to the flask and dilute the solution to the mark with amyl alcohol. At the same time carry out a blank test on the reagents alone. Measure the absorbance of the solution at a wavelength of 545 nm, using the reagent blank solution as reference standard, and read the amount of copper present from the calibration chart (see G4.1). Alternatively, compare the colour of the solution with the series of prepared colour standards in matched Nessler cylinders, noting the copper content of the standard that most nearly matches the test solution. G.5 CALCULATION Copper content expressed as milligrammes of copper, Cu, per kilogramme = 0.1 x M7 where M7 = mass of copper found (µg).

DKS 2258:2010

ANNEX H METHOD FOR THE DETERMINATION OF CONDUCTIVITY

H1. OUTLINE OF THE METHOD A sample of the water is boiled in a conical flask for a period of 5 min. The flask is sealed and the flask and contents cooled to 20 ± 2°C and the conductivit y measured within 15 min. H2. APPARATUS The following apparatus is required; (a) 500 ml conical flask, fitted with a ground glass joint (b) Guard tube, fitted with a ground glass joint, containing soda lime (self-indicating) nominal aperture size 0.71 mm to 1.18 mm. c) Conductivity meter H3. PROCEDURE Transfer 400 ml of the water into the flask. Heat the flask until the water boils and continue boiling for 5 min. Remove the flask from the heat and immediately insert the guard tube. Cool the flask and contents rapidly under running water. Measure the conductivity within 15 min of cooling to 20 ±2ºC.