| Preparation of Reagents and Chemicals |
| 1.0 PROCEDURE 1.1 Acetic Acid, 1 M: Solutions of any Molarity 1M may be prepared by diluting 57 x ml (60 x g) of glacial acetic acid to 1000 ml with purified water. 1.2 Acetic Acid, Dilute Reagents : Contains approximately 6 per cent w/w of CH3COOH. Dilute 57 ml of glacial acetic acid to 1000 ml with purified water. 1.3 Acetic Acid Sp.: Acetic acid which complies with the following test. Make 25 ml alkaline with dilute ammonia solution Sp., add 1 ml of potassium cyanide solution Sp., dilute to 50 ml with purified water and add 2 drops of sodium sulphide solution; no darkening is produced. 1.4 Aluminium Chloride Solution: Dissolve 35.9 g of anhydrous aluminium chloride is sufficient water to produce 100 ml, add 0.5 g, of activated charcoal, stir for 10 minutes, filter and add to the filtrate with continuous stirring sufficient of a 10 per cent w/v solution of sodium hydroxide to adjust the pH to about 1.5. CAUTION — Care should be taken in dissolving anhydrous aluminium chloride in purified water. 1.5 Amino hydroxy naphthalene sulphonic Acid Solution: Dissolve 0.25 g of 4-amino-3- ydroxynaphthalene-1-sulphonic acid in about 75 ml of a 15 per cent w/v solution of sodium metabisulphite, warming to assist solution if necessary. Add 25 ml of a 20 per cent w/v solution of sodium sulphite, mix and add sufficient of the sodium metabisulphite solution to produce 100 ml. 1.6 4-Aminophenol: p-Aminophenol; NH2C6H4OH = 109.13 A white or almost white, crystalline powder; mp, about 186º. 1.7 Ammonia, 1 M: Solutions of any molarity 1M may be prepared by diluting 75 ml of strong ammonia solution to 1000 ml with purified water. 1.8 Ammonia-Ammonium Chloride Solution, Strong Reagents: Dissolve 67.5 g of ammonium chloride in 740 ml of strong ammonia solution and add sufficient purified water to produce 1000 ml. 1.9 Ammonia, 1 M Ethanolic; Ammoniacal Ethanol, 1M: Solutions of any morality 1 M may be prepared by diluting 75 ml of strong ammonia solution to 1000 ml make up with make up methanol. 1.10 Ammonia, 1 M Methanolic Reagents; Ammoniacal Methanol, 1 M: Solutions of any molarity x M may be prepared by diluting 75 ml of strong ammonia solution to 1000 ml make up with methanol. 1.11 Ammonia Solution, Dilute: Contains approximately 10 per cent w/w of NH3. Dilute 425 ml of strong ammonia solution to produced 1000 ml. Store protected from moisture in a cool place. 1.12 Ammonia, 18 M: For 18M and 13.5 M ammonia use analytical reagent grade of commerce containing 35 per cent and 25 per cent w/v of ammonia and weighing 0.88 g and 0.91 g per ml, espectively. Solutions of any molarity x M may be prepared by diluting 75x ml of 13.5 M ammonia or 56x ml of 18 M ammonia to 1000 ml with purified water. 1.13 Ammonia Solution Sp.: Strong ammonia solution which complies with the following additional test. Evaporate 10 ml to dryness on a purified water-bath. To the residue add 1 ml of dilute HCl acid Sp. and evaporate to dryness. Dissolve the residue in 2 ml of dilute acetic acid Sp., add sufficient purified water to produce 25 ml and add 10 ml of hydrogen sulphide solution. Any darkening produced is not greater than that of a blank solution containing 2 ml of dilute acetic acid Sp., 1.0 ml of standard lead solution and sufficient purified water to produce 25 ml. 1.14 Ammonia Solution Sp., Dilute: Dilute ammonia solution which complies with the following test.To 20 ml add 1 ml of potassium cyanide solution Sp., dilute to50 ml with purified water and add 0.1 ml of sodium sulphide soln; no darkening is produced. 1.15 Ammonia Solution, Strong Reagents: Ammonia: NH3 = 17.03Analytical reagent grade of commerce. Contains 25.0 per cent w/w of NH3 (limits, 24.5 to 25.5); wt. per ml, about 0.91 g; strength, about 13.5M A clear, colourless liquid; odour, strongly pungent and characteristic. Store protected from moisture in a cool place. 1.16 Ammonium Acetate: CH3COONH4 = 77.08 Analytical reagent grade of commerce. A colourless crystals or crystalline masses; odour, slightly acetous; so deliquescent. 1.17 Ammonium Acetate, 0.1 M: Dissolve 7.71 g of ammonium acetate in 200 ml of purified water, add 1 ml of glacial acetic acid and dilute to 1000 ml with purified water. 1.18 Ammonium Acetate Solution: Dissolve 150 g of ammonium acetate in 200 ml of water, add 3 ml of glacial acetic acid and dilute to 1000 ml with purified water. Use a freshly prepared solution. 1.19 Ammonium Carbonate, 2 M: Dissolve 156 g of ammonium carbonate in sufficient purified water to produce 1000 ml. 1.20 Ammonium Chloride, 2 M: Dissolve 106.98 g of ammonium chloride in sufficient purified water to produce 1000 ml. 1.21 Ammonium Chloride-Ammonium Hydroxide Solution: Mix 1 volume of purified water and 2 volumes of strong ammonia solution and saturate with ammonium chloride. 1.22 Ammonium Chloride Solution: A 10 per cent w/v solution of ammonium chloride. 1.23 Ammonium Citrate Solution: Dissolve, with cooling, 500 g of citric acid in a mixture of 200 ml of water and 200 ml of strong ammonia solution, filter and dilute to 1000 ml with water. Reagents 1.24 Ammonium Citrate Solution, Alkaline Reagents: Dissolve 9.00005 g of citric acid in about 150 ml of purified water and add gradually 50 ml of 5 M ammonia. Add 10 ml of chloroform and dithizone solution in 0.2-ml quantitates until the chloroform layer, after vigorous shaking, is blue or purple. Discard the chloroform layer, add 10 ml of chloroform and 0.2 ml of dithizone solution, shake and allow to separate; the chloroform layer remains green. Discard the chloroform layer and wash the aqueous layer with successive quantities, each of 15 ml, of chloroform until the washings are colourless. Dilute the aqueous layer to 300 ml of with purified water. 1.25 Ammonium Citrate Solution Sp.: Dissolve 40 g of citric acid in 90 ml of purified water, add two drops of phenol red solution and then add slowly strong ammonia solution until the solution acquires a reddish colour. Remove any lead present by extracting the solution with successive quantities, each of 30 ml, of dithizone extraction solution until the dithizone solution retains its orange-green colour. 1.26 Ammonium Molybdate Solution: A 10 per cent w/v solution of ammonium molybdate. 1.27 Ammonium Molybdate Solution, Ethanolic SOLUTION 1 — Dissolve 5 g of ammonium molybdate in 20 ml of water with the aid of heat. SOLUTION 2— Mix 150 ml of ethanol (95 %) with 150 ml of purified water and add, with cooling, 100 ml of sulphuric acid. Add 80 volumes of solution II to 20 volumes of solution I immediately before use. 1.28 Ammonium Molybdate-Sulphuric Acid Solution: Dissolve 10 g of ammonium molybdate in sufficient purified water to produce 100 ml and add the solution slowly to 250 ml of cold 10 M sulphuric acid. Store in light-resistant plastic bottles Analytical reagent grade of commerce. 1.29 Ammonium Nitrate, 0.007 M: Dissolve 0.5603 g of ammonium nitrate in sufficient purified water to produce 1000 ml. 1.30 Ammonium Oxalate: (COONH4)2, H2O = 142.11 Analytical reagent grade of commerce. A colourless crystals. 1.31 Ammonium Oxalate, 0.1 M: Dissolve 14.21 g of ammonium oxalate in sufficient purified water to produce 1000 ml. 1.32 Ammonium Oxalate Solution: A 4.0 % w/v soln. of ammonium oxalate. 1.33 Ammonium Sulphide Solution: Saturate 120 ml of 6 M ammonia with hydrogen sulphide (H2S) and add 80 ml of 6 M ammonia. The soln should be freshly prepared for use. 1.34 Ammonium Thiocyanate, x M: Solutions of any molarity x M may be prepared by dissolving 76.12x g in sufficient purified water to produce 1000 ml. 1.35 Ammonium Thiocyanate Solution: A 10 per cent w/v solution of ammonium Thiocyanate. Antimony Trichloride Reagent SOLUTION I — Dissolve 110 g of antimony trichloride in 400 ml of 1,2-dichloroethane. Add 2 g of anhydrous alumina, mix and filter through sintered glass into a 500-ml volumetric flask. Dilute to 500 ml with 1,2-dichloroethane and mix. Absorbance of the resulting solution measured in a 2-cm cell at about 500 nm, not more than 0.07 using 1,2-dichloroethane as the blank. SOLUTION 2 — Mix 100 ml of colourless, distilled acetyl chloride and 400 ml of 1,2-dichloroethane and store in a cool place. Mix 90 ml of solution I and 10 ml of Solution 2. Store in amber glass-stoppered bottles and use within 7 days. Discard any reagent in which colour develops. |
