| 0.1M Ceric ammonium nitrate |
| 1.0 Scope: This procedure is applicable for preparation and standardization of 0.1M ceric ammonium nitrate. 2.0 Apparatus: 2.1 1000 ml, 250 ml and 100ml volumetric flask 2.2 500 ml glass-stoppered, conical flask 2.3 100 ml graduated burette 2.4 25 ml and 1ml volumetric pipette 3.0 Reagents: 3.1 Ceric ammonium nitrate AR grade 3.2 Arsenic trioxide AR grade 3.3 Sodium hydroxide solution (8 % w/v) 3.4 Sulphuric Acid AR grade 3.5 Dilute sulphuric acid solution 3.6 Osmic acid solution 3.7 Ferroin sulphate solution 4.0 Preparation of Reagents: 4.1 Sodium hydroxide solution solution: Dissolve about 8.0 g of sodium hydroxide in distilled water and dilute 100 ml. and store in well fitted plastic bottle. 4.2 Dilute sulphuric acid solution: Dilute 14.3 ml of sulphuric acid to 250 ml with distilled water and store in well fitted transparent glass bottle. To read this GTP click here Limit Test for Iron. 4.3 Osmic acid solution Dissolve about 1.0g of Osmic acid in distilled water and dilute 100 ml. and store in well-fitted transparent glass bottle. 4.4 Ferroin sulphate solution: Dissolve about 0.7g of ferrous sulphate and 1.5g of 1,10 phenanhroline hydrochloride in 70 ml of distilled water and add sufficient distilled water to produce 100 ml. and store in well fitted transparent glass bottle. 5.0 Preparation: Shake a solution containing 56.0 ml of sulphuric acid and 54.8 g of ceric ammonium nitrate for 2 minutes and carefully add five successive quantities, each of 100 ml of water, shaking after each dilution addition, dilute the clear solution to 1000.0 ml with water. After 10 days, standardized the solution. 6.0 Standardization: Weigh accurately about 0.2 g or 200.0mg of arsenic trioxide, previously dried at 105 degree Celsius for 1 hour, and transfer to a 500- ml conical flask. By Add 25.0 ml of a 8.0% w/v solution of sodium hydroxide, swirl to dissolve, add 100 ml of water and mix. Add 30 ml of dilute sulphuric acid, 0.15 ml of osmic acid solution, 0.1 ml of ferroin sulphate solution and slowly titrate with the ceric ammonium nitrate solution until the pink colour is changed to a very pale blue, adding the titrant slowly towards the end-point in quality control. Each ml of 0.1 M ceric ammonium nitrate is equivalent to 0.004946 g of As2O3. 7.0 Calculation: Weight X 0.1 N= ————————- V X 0.004946 Where: N = molarity of ceric ammonium nitrate solution W = weight of arsenic trioxide in g V = volume consume of 0.1M ceric ammonium nitrate solution in ml. 8.0 Storage: Store in a well fitted light resistant bottle. |