| Method of analysis Sodium Hexameta Phosphate (SHMP) |
| 1.0 PROCEDURE 1.1 Sampling Quantity: For solid 30 gm, for Liquid 50 ml. 1.2 Description: In solid form: White or almost white, crystalline powder or colourless crystals. Spread approx. 2.0 gm of sample in a clean dry Petri dish and observe with unaided eye and observe against specification. In Liquid: Clear colorless to slightly yellow liquid free from suspended particles. 1.3 Assay: [Sodium Hexameta Phosphate](62.0 % to 69.0 %) 1.3.1 Reagents a) Ammonium Molybdate (10 percent w/v): Dissolve 10 g of Ammonium Molybdate in 100 ml distilled water. b)Dilute Nitric Acid (2 N): Mix 190 ml of 50 percent Nitric acid with distilled water to produce 1000 ml. c) Nitric Acid (2 percent): Dilute 10ml of conc. Nitric acid (70 percent) to 710ml with distilled water. d) Potassium Nitrate (1 percent): Dissolve 1 g potassium nitrate in 100 ml of distilled water. e) Phenolphthalein , 1N Sodium hydroxide, 1N Sulphuric acid. To read this SOP click here Preparation and Standardization of 0.1M Hydrochloric acid. 1.3.2 Procedure for Sodium Hexameta Phosphate Dry about 10g of Sodium Hexa Meta Phosphate at 110°C overnight. Keep in a desiccators and bring to room temperature. Take 1.0 gram (accurately weighed) in a 100ml beaker. Dissolve in 25.0 ml of distilled water. Transfer to a 500ml standard volumetric flask. Make up the volume to 500 ml with distilled water (1g Sodium Hexa Meta Phosphate /500ml). Take exactly 25 ml (50mg Sodium Hexa Meta Phosphate) into a 500ml beaker. Add 5ml of conc. Nitric acid and stir well. Add 220 ml of distilled water kept at 60°C. Stir well. Wait for 10 minutes. Add 10g of Ammonium Nitrate (purified).At 50° C, add 100ml of 10percent Ammonium Molybdate (freshly prepared) and stir well with a glass rod for 10 minutes. Repeat stirring after 1minute gap. Keep for 30 minutes. Filter the precipitate using Whatman No. 40 circles and wash with 10ml of dilute nitric acid (2N), followed by potassium nitrate solution (1 percent) until the filtrate is no longer acidic to litmus (Blue litmus remains blue). Dissolve the precipitate from the filter paper in 60ml of 1N sodium hydroxide, add phenolphthalein, and titrate the excess sodium hydroxide with 1Nsulphuric acid. Calculate the volume of 1N sodium hydroxide consumed by the precipitate. Each ml of 1N sodium hydroxide consumed is equivalent to 0.003086 g P2O5. Calculation Sodium Hexa Meta Phosphate (68percent P2O5) Phosphates as P2O5 =percent by mass on dry basis. Where, V1 = Volume of H2SO4 (titre value), N1 = Normality of H2SO4, N2 = Normality of NaOH), Wt. = mass in gram of the material taken for the test. [60-(V1xN1/N2)] x [0.06172/wt.] Alternatively calculate the P2O5 content as follows; P2O5 content of SHMP = (‘x’ × 6.2%) Where, ‘x’ is the volume of 1N sodium hydroxide NaOH (‘x’= 60ml – unused volume of 1N NaOH) e.g., if ‘x’ is equal to 11 ml, P2O5 content of SHMP = 11 × 6.2 = 68.2%. |
