Packaging and storage—
Preserve in well-closed containers in a dry place.
Identification—
A:
Dissolve 1 g of Gelatin in 100 mL of hot water. To this solution add about 20 mL of a mixture of 0.2 M potassium dichromate and 3 N hydrochloric acid (4:1): a yellow precipitate is formed.
B:
To a hot solution (0.2 mg per mL) add
tannic acid TS: turbidity is produced.
Microbial limits 
61
—
The total bacterial count does not exceed 1000 cfu per g, and the tests for
Salmonella species and
Escherichia coli are negative.
Residue on ignition 281—
Incinerate 5.0 g without the use of sulfuric acid, but with the addition of 1.5 to 2.0 g of paraffin to avoid loss due to swelling, then finish ashing in a muffle furnace at 550
for 15 to 20 hours: the weight of the residue does not exceed 2.0%.
Odor and water-insoluble substances—
A hot solution (1 in 40) is free from any disagreeable odor, and when viewed in a layer 2 cm thick is only slightly opalescent.
Sulfur dioxide—
Dissolve 20.0 g in 150 mL of hot water in a flask having a round bottom and a long neck, add 5 mL of phosphoric acid and 1 g of sodium bicarbonate, and at once connect the flask with a condenser.
[NOTE—Excessive foaming can be alleviated by the addition of a few drops of a suitable antifoaming agent.
] Distill 50 mL, receiving the distillate under the surface of 50 mL of 0.1 N iodine. Acidify the distillate with a few drops of hydrochloric acid, add 2 mL of
barium chloride TS, and heat on a steam bath until the liquid is nearly colorless. The precipitate of barium sulfate, if any, when filtered, washed, and ignited, weighs not more than 3 mg, corresponding to not more than 0.004% of sulfur dioxide, correction being made for any sulfate that may be present in 50 mL of the 0.1 N iodine. Gelatin used in the manufacture of capsules or for the coating of tablets yields not more than 109.3 mg of barium sulfate, corresponding to not more than 0.15% of sulfur dioxide.
Arsenic, Method I 211—
Pepsin solution—
Dissolve 0.5 g of pepsin in 80 mL of 0.1 N hydrochloric acid, dilute with 0.1 N hydrochloric acid to 100 mL, and mix.
Standard preparation—
Transfer 3.0 mL of Standard Arsenic Solution to an arsine generator flask, and dilute with Pepsin solution to 52 mL. Add 3 mL of hydrochloric acid and 4 mL of isopropyl alcohol, and mix.
Test preparation—
Mix 3.75 g with 40 mL of
Pepsin solution in an arsine generator flask. Heat cautiously to a temperature between 65
and 70
, and, while maintaining this temperature for 30 minutes, sonicate the solution for 2 minutes at each 10-minute interval of heating time. Cool, wash down the sides of the generator with
Pepsin solution, and dilute with
Pepsin solution to 52 mL. Add 3 mL of hydrochloric acid and 4 mL of isopropyl alcohol, and mix.
Procedure—
Proceed as directed for Procedure except omit the addition of 20 mL of 7 N sulfuric acid and 1 mL of isopropyl alcohol to the Standard preparation and to the Test preparation. The resulting solution obtained from the Test preparation meets the requirements of the test: the limit is 0.8 ppm.
Heavy metals 231—
To the residue obtained in the test for
Residue on ignition add 2 mL of hydrochloric acid and 0.5 mL of nitric acid, and evaporate on a steam bath to dryness. To the residue add 1 mL of 1 N hydrochloric acid and 15 mL of water, and warm for a few minutes. Filter, and wash with water to make the filtrate measure 100 mL. Dilute 8 mL of the solution with water to 25 mL: the limit is 0.005%.
