NaI -- 149.89 -- [7681-82-5].
Sodium Iodide contains not less than 99.0 percent and not more than 101.5 percent of NaI, calculated on the anhydrous basis.
Identification: A solution (1 in 20) responds to the tests for Sodium and for Iodide.
Alkalinity: Dissolve 1.0 g in 10 mL of water, and add 0.15 mL of 0.10 N sulfuric acid: no red color is produced by the addition of 1 drop of PhPh TS.
Water: not more than 2.0%.
Iodate: It meets the requirements of the test for Iodate under Potassium Iodide, 100 mg of Sodium Iodide being used in the control.
Thiosulfate and barium: It meets the requirements of the test for Thiosulfate and barium under Potassium Iodide.
Potassium: A solution of 1.0 g in 2 mL of water yields no precipitate with 1.0 mL of sodium bitartrate TS.
Heavy metals: Dissolve 2.0 g in 25 mL of water: the limit is 0.001%.
Limit of nitrate, nitrite, and ammonia: Add 5 mL of 1 N sodium hydroxide and about 200 mg of aluminum wire to a solution of 1.0 g of Sodium Iodide in 5 mL of water, contained in a test tube of about 40-mL capacity. Insert a pledget of purified cotton in the upper portion of the test tube, and place a piece of moistened red litmus paper over the mouth of the tube. Heat in a steam bath for 15 minutes: no blue coloration of the paper is discernible.
Assay: Weigh accurately about 500 mg of Sodium Iodide, and dissolve in about 10 mL of water. Add 35 mL of hydrochloric acid, and titrate with 0.05 M potassium iodate VS until the dark brown solution which is produced becomes pale brown. Add 1 mL of amaranth TS, and continue the titration slowly until the red color just changes to yellow. Each mL of 0.05 M potassium iodate is equivalent to 14.99 mg of NaI.
NaI -- 149.9 -- 7681-82-5
DEFINITION
Content:
99.0 per cent to 100.5 per cent (dried substance).
CHARACTERS
Appearance: White or almost white, crystalline powder or colourless crystals, hygroscopic.
Solubility: Very soluble in water, freely soluble in ethanol (96 per cent).
IDENTIFICATION
A. Solution S (see Tests) gives the reactions of iodides.
B. Solution S gives the reactions of sodium.
TESTS
Solution S: Dissolve 10.0 g in carbon dioxide-free water R prepared from distilled water R and dilute to 100 ml with the same solvent.
Appearance of solution: Solution S is clear (2.2.1) and colourless.
Alkalinity: To 12.5 ml of solution S add 0.1 ml of bromothymol blue solution R1. Not more than 0.7 ml of 0.01 M hydrochloric acid is required to change the colour of the indicator.
Iodates: To 10 ml of solution S add 0.25 ml of iodide-free starch solution R and 0.2 ml of dilute sulphuric acid R and allow to stand protected from light for 2 min. No blue colour develops.
Sulphates: Maximum 150 ppm.
Thiosulphates: To 10 ml of solution S add 0.1 ml of starch solution R and 0.1 ml of 0.005 M iodine. A blue colour is produced.
Iron: Maximum 20 ppm.
Dilute 5 ml of solution S to 10 ml with water R.
Heavy metals: Maximum 10 ppm.
Loss on drying: Maximum 3.0 per cent, determined on 1.00 g by drying in an oven at 105 °C for 3 h.
ASSAY
Dissolve 1.300 g in water R and dilute to 100.0 ml with the same solvent. To 20.0 ml of the solution add 40 ml of hydrochloric acid R and titrate with 0.05 M potassium iodate until the colour changes from red to yellow. Add 5 ml of chloroform R and continue the titration, shaking vigorously, until the chloroform layer is decolorised. 1 ml of 0.05 M potassium iodate is equivalent to 14.99 mg of NaI.
NaI
Formula Wt 149.89
CAS Number 7681-82-5
REQUIREMENTS
Assay: Minimum 99.5% NaI
pH of a 5% solution: 6.0-9.0 at 25C
MAXIMUM ALLOWABLE
Insoluble matter: 0.01%
Chloride and bromide (as Cl): 0.01%
Iodate (IO3): 3 ppm
Nitrogen compounds (as N): 0.002%
Phosphate (PO4): 0.001%
Sulfate (SO4): 0.005%
Barium (Ba): 0.002%
Heavy metals (as Pb): 5 ppm
Iron (Fe): 5 ppm
Calcium (Ca): 0.002%
Magnesium (Mg): 0.001%
Potassium (K): 0.01%
