Packaging and storage—
Preserve in well-closed containers.
Identification—
A filtered extract of Tablets responds to the tests for
Sodium 
191
and for
Chloride 191.
Iodide or bromide—
Digest 2.0 g of powdered Tablets with 25 mL of warm alcohol for 3 hours, cool, and filter. Evaporate the filtrate to dryness, dissolve the residue in 5 mL of water, filter if necessary, and add 1 mL of chloroform. Cautiously introduce, dropwise, with constant agitation, 5 drops of dilute chlorine TS (1 in 3): the chloroform does not acquire a violet, yellow, or orange color.
Barium—
Digest 4.0 g of powdered Tablets with 20 mL of water, filter, and divide the solution into two equal portions. To one portion add 2 mL of 2 N sulfuric acid and to the other add 2 mL of water: the solutions are equally clear after standing for 2 hours.
Calcium and magnesium—
Digest 1 g of powdered Tablets with 50 mL of water, and filter. Add 4 mL of 6 N ammonium hydroxide to the filtrate, and divide the mixture into two equal portions. Treat one portion with 1 mL of
ammonium oxalate TS and the other portion with 1 mL of
dibasic sodium phosphate TS: neither mixture becomes turbid within 5 minutes.
Assay—
Dissolve a counted number of not less than 20 Tablets in about 100 mL of water, filter into a 500-mL volumetric flask, and wash the original container and the filter with 100 mL of water in divided portions, adding the washings to the original filtrate. Dilute with water to volume. Pipet a volume of the solution, equivalent to about 90 mg of sodium chloride, to a conical flask, and add 10 mL of glacial acetic acid, 75 mL of methanol, and 0.5 mL of
eosin Y TS. Titrate, with shaking, with 0.1 N silver nitrate VS to a pink endpoint. Each mL of 0.1 N silver nitrate is equivalent to 5.844 mg of NaCl.
