Packaging and storage—
Preserve in tight containers.
Residue on ignition 
281
—
To 20 mL add 2 drops of sulfuric acid, evaporate to dryness, and ignite: not more than 2 mg of residue remains (about 0.008%).
Bromide or iodide, Free bromine or chlorine, Sulfate, and Sulfite—
Dilute it with 2 volumes of water, to perform the following tests.
Bromide or iodide—
Add 1 mL of chloroform to 10 mL of the dilution, and cautiously add, dropwise, with constant agitation, chlorine TS that has been diluted with an equal volume of water: the chloroform remains free from even a transient yellow, orange, or violet color.
Free bromine or chlorine—
Add 1 mL of
potassium iodide TS and 1 mL of chloroform to 10 mL of the dilution, and agitate the mixture: the chloroform remains free from any violet coloration for at least 1 minute.
Sulfate—
To a mixture of 3 mL of the dilution and 5 mL of water add 5 drops of
barium chloride TS: neither turbidity nor precipitate appears within 1 hour.
Sulfite—
On the completion of the test for
Sulfate, the addition to the liquid of 2 drops of 0.1 N iodine produces neither turbidity nor decolorization of the iodine.
Heavy metals 231—
Evaporate 3.4 mL (4 g) on a steam bath to dryness, add 2 mL of 1 N acetic acid to the residue, then dilute with water to 25 mL: the limit is 5 ppm.
Assay—
Place about 3 mL of Hydrochloric Acid in a glass-stoppered flask, previously tared while containing about 20 mL of water, and weigh again to obtain the weight of the substance under assay. Dilute with about 25 mL of water, add methyl red TS, and titrate with 1 N sodium hydroxide VS. Each mL of 1 N sodium hydroxide is equivalent to 36.46 mg of HCl.
