Packaging and storage
Preserve in tight, light-resistant containers.
Identification
Triturate a quantity of finely powdered Tablets, equivalent to about 1 g of iopanoic acid, with two 10-mL portions of solvent hexane, and decant and discard the liquid. Allow the residue to dry spontaneously, triturate with 15 mL of acetone, and filter. Repeat the trituration with another 15-mL portion of acetone, evaporate the combined filtrates on a steam bath to a volume of not more than 1 mL, add, with constant stirring, 20 mL of water, filter, wash the precipitate with two 5-mL portions of water, and dry at 105
for 2 hours: the iopanoic acid so obtained melts between 150
and 158
, with decomposition, and responds to the
Identification test under
Iopanoic Acid.
Halide ions
A portion of the powdered Tablets prepared for the
Assay, equivalent to about 500 mg of iopanoic acid, meets the requirements of the test for
Halide ions under
Iopanoic Acid.
Assay
Weigh and finely powder not fewer than 20 Tablets. Weigh accurately a portion of the powder, equivalent to about 1 g of iopanoic acid, and triturate with 10 mL of solvent hexane. Allow the mixture to settle, decant the hexane through a small filter, repeat the trituration with 10 mL of solvent hexane, filter through the same filter, and discard the filtrates. Warm the residue with 10 mL of neutralized alcohol at 70
, filter through the same filter, and wash the undissolved residue with four 10-mL portions of neutralized alcohol at 70
, passing the washings through the same filter. Cool the combined filtrate and washings to room temperature, add 3 to 5 drops of
thymol blue TS, and titrate with 0.1 N sodium hydroxide VS. Each mL of 0.1 N sodium hydroxide is equivalent to 57.09 mg of C
11H
12I
3NO
2.