BS 1728-14-1965.pdf

BRITISH STANDARD BS 1728-14: 1965 Method for the determination of Nickel In aluminium Part 2: Magnesium; Part 3: Zinc (mercuric potassium thiocyanate method); Part 4: Zinc (polarographic method); Part 5: Copper (absorptiometric method); Part 6: Iron (volumetric-titanous chloride method); Part 7: Zinc (zinc oxide method); Part 8: Iron (absorptiometric 1 : 10 phenanthroline method); Part 9: Manganese (volumetric-arsenite/nitrite method); Part 10: Manganese (absorptiometric method); Part 11: Silicon (perchloric acid method); Part 12: Silicon (absorptiometric-molybdenum blue method); Part 13: Titanium (absorptiometric-chromotropic acid method). The preparation of this series of methods has been authorized by the Non-Ferrous Metals Industry Standards Committee as part of a general programme for the standardization of methods for the sampling and analysis of non-ferrous metals. The methods have been found to give reliable and reproducible results and, while in some instances they may appear to be lengthy, it should be appreciated that they are primarily intended as “referee” methods to be used in cases of dispute. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 and 2 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-14:1965 © BSI 10-19991 Introduction a) Principle. The alloy is dissolved in hydrochloric and nitric acids. Heavy metals are precipitated with sodium hydroxide and copper is removed by electrolysis. The nickel is then precipitated with dimethylglyoxime and determined gravimetrically. b) Range. The method is recommended for nickel contents from 0.2 per cent to 3 per cent. c) Reproducibility. Experiments have been carried out independently by a number of analysts using this method. The degree of reproducibility that can be expected is shown by the following results obtained: Apparatus a) Class A volumetric glassware complying with the relevant British Standards shall be used throughout. b) Platinum-gauze electrodes of stationary type and of suitable size. c) Electrodeposition apparatus fitted with stirrer or means of agitation, e.g. compressed air, and capable of providing a direct current of 3 amperes. Solutions required All reagents shall be of the highest purity obtainable, and distilled water shall be used throughout. Citric acid (20 per cent w/v). Dissolve 200 g of citric acid (C6H8O7.H2O) in water, dilute to 1 litre and mix. Dimethylglyoxime (1 per cent w/v). Dissolve 10 g of dimethylglyoxime in potassium hydroxide solution (3 per cent w/v) dilute to 1 litre with the potassium hydroxide solution and mix. Hydrazine hydrochloride (10 per cent w/v). Dissolve 100 g of hydrazine hydrochloride in water, dilute to 1 litre and mix. Hydrochloric acid (50 per cent v/v). Dilute 500 ml of hydrochloric acid (sp. gr. 1.16 to 1.18) to 1 litre and mix. Nitric acid (50 per cent v/v). Dilute 500 ml of nitric acid (sp. gr. 1.42) to 1 litre and mix. Sodium hydroxide (0.5 per cent w/v). Dissolve 5 g of sodium hydroxide in water, dilute to 1 litre and mix. Sulphuric acid (50 per cent v/v). To 400 ml of water add cautiously 500 ml of sulphuric acid (sp. gr. 1.84) mix, cool, dilute to 1 litre and mix. Sulphurous acid. Pass sulphur dioxide gas into 100 ml of water until a saturated solution is obtained. Procedure Adjust the weight of sample and quantities of reagents as follows: Weigh the appropriate quantity of sample, transfer to a 250 ml beaker and add the appropriate quantity of hydrochloric acid (50 per cent). When the reaction subsides add 5 ml of nitric acid (50 per cent), boil for 5 minutes and dilute to 100 ml. Filter off the insoluble matter on a paper pulp pad or a medium texture filter paper1) and wash with hot water. Reserve the filtrate and washings. Transfer the pad or paper and the precipitate to a platinum vessel of suitable size, dry, and ignite at 550650 °C for 30 minutes. Cool, add 5 ml of hydrofluoric acid2), then add nitric acid (50 per cent) dropwise to oxidize the silicon until a clear solution is obtained. Add a few drops of sulphuric acid (50 per cent) and evaporate to dryness. Take up the residue with a few ml of water containing a few drops of sulphuric acid (50 per cent) and add this solution to the main filtrate. Adjust the volume to about 200 ml. Weigh the appropriate quantity of sodium hydroxide, transfer to a 600 ml beaker and dissolve in 100 ml of water. Add 5 ml of hydrazine hydrochloride solution (10 per cent), mix, then transfer to this the sample solution with continuous stirring. Heat to boiling. Continue boiling for 12 minutes, then allow the residue to settle, filter through a hardened medium texture filter paper3) or paper pulp pad and wash well with hot sodium hydroxide solution (0.5 per cent). Nickel contentStandard deviation per cent 0.24 0.53 0.67 2.50 0.010 0.010 0.013 0.032 Nickel content Sample weight Hydrochloric acid (50 per cent) Sodium hydroxide per cent less than 1 over 1 g 2 1 ml 50 25 g 30 20 1) Whatman No. 40 is suitable. 2) This refers to the usual analytical reagent of 40 per cent w/w. 3) Whatman No. 540 is suitable. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-14:1965 2 © BSI 10-1999 Dissolve the residue with hot nitric acid (50 per cent) adding a little sulphurous acid if manganese is present. Wash with hot water, add 10 ml of sulphuric acid (50 per cent) and evaporate to dense white fumes. Cool, add 100 ml of water and heat until soluble salts are dissolved. Filter off the silica on a medium texture filter paper4) and wash with hot water (Note 1). Adjust the volume to 150 ml and add 5 ml of nitric acid (50 per cent). Insert a pair of platinum electrodes in the solution and electrolyse with stirring at about 3 amp for 20 minutes. Check for completeness of deposition of copper by adding a little water and continue the electrolysis; no further copper should be deposited on the newly immersed portion of the cathode. When deposition is complete, without interrupting the current, remove the beaker containing the electrolyte and wash down the electrodes into the same beaker. Adjust the volume of the solution to 200 ml, add 10 ml of citric acid solution (20 per cent) and neutralize with ammonia solution (sp. gr. 0.880.91). Heat to about 90 °C and add, with stirring, 20 ml of dimethylglyoxime solution (1 per cent) for up to 20 mg of nickel and 5 ml for each additional 10 mg of nickel. Allow to stand without further heating for 30 minutes (Note 2), cool to room temperature, filter through a weighed sintered glass crucible (porosity 3) and wash with cold water. Dry the crucible and precipitate at 110120 °C for two hours, cool and weigh. Calculation NOTE 1If the copper content is known to be less than 0.1 per cent omit the electrolysis and continue from paragraph 8 of the procedure. NOTE 2Allow the solution to stand for 2 hours for nickel contents below 0.5 per cent. 4) Whatman No. 40 is suitable. where A = weight (g) of nickel, glyoxime, W = weight (g) of sample taken. Nickel per cent A20.32× W - -= Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-14: 1965 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. 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