Packaging and storage—
Preserve in well-closed containers.
Alkalinity—
Dissolve 1.0 g in 10 mL of water, and add 0.1 mL of 0.1 N sulfuric acid and 1 drop of
phenolphthalein TS: no color is produced.
Iodate—
Dissolve 1.1 g in sufficient ammonia- and carbon dioxide-free water to obtain 10 mL of solution, and transfer to a color-comparison tube. Add 1 mL of starch TS and 0.25 mL of 1.0 N sulfuric acid, mix, and compare the color with that of a control containing, in a similar volume, 100 mg of Potassium Iodide, 1 mL of standard iodate solution [prepare by diluting 1 mL of potassium iodate solution (1 in 2500) with water to 100 mL], 1 mL of
starch TS, and 0.25 mL of 1.0 N sulfuric acid. Any color produced in the solution of the test specimen does not exceed that in the control: not more than 4 µg per g is found.
Limit of nitrate, nitrite, and ammonia—
To a solution of 1 g in 5 mL of water contained in a test tube of about 40-mL capacity add 5 mL of 1 N sodium hydroxide and about 200 mg of aluminum wire. 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 the test tube and its contents in a steam bath for 15 minutes: no blue coloration of the paper is discernible.
Thiosulfate and barium—
Dissolve 0.5 g in 10 mL of ammonia- and carbon dioxide-free water, and add 2 drops of 2 N sulfuric acid: no turbidity develops within 1 minute.
(Official until July 1, 2008)
Assay—
Dissolve about 500 mg of Potassium Iodide, accurately weighed, in about 10 mL of water, and add 35 mL of hydrochloric acid. Titrate with 0.05 M potassium iodate VS until the dark brown solution which is produced becomes pale brown. Add 2 to 3 drops 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 16.60 mg of KI.
191
and for Iodide 
for 4 hours: it loses not more than 1.0% of its weight.