Labeling—
The package bears a statement to the effect that the sterility of Oxidized Regenerated Cellulose cannot be guaranteed if the package bears evidence of damage, or if the package has been previously opened. Oxidized Regenerated Cellulose meets the requirements for
Labeling under
Injections 
1
.
Identification—
To about 200 mg add 10 mL of 0.25 N sodium hydroxide, and shake for 1 minute. Add 10 mL of water, and shake: the solution so obtained shows no more than a slight haze and is substantially free from fibers and from foreign particles. Allow to stand for 10 minutes: any swollen fibers initially present are no longer visible. Acidify with 3 N hydrochloric acid: a flocculent white precipitate is formed.
Sterility 71:
meets the requirements; the test specimen weighing approximately 250 mg and 0.5 mL of 0.1 N sodium hydroxide being added to the portions of media used.
Loss on drying 731—
Dry about 150 mg at 90
for 2 hours: it loses not more than 15% of its weight.
Nitrogen content—
Transfer about 1 g, previously dried and accurately weighed, to a 500-mL Kjeldahl flask. Arrange a 125-mL conical flask, containing 30 mL of boric acid solution (1 in 25) and 6 drops of mixed indicator (1 part of
methyl red TS and 4 parts of
bromocresol green TS), beneath the condenser of the distillation apparatus so that the tip of the condenser is well below the surface of the boric acid solution. To the Kjeldahl flask containing the sample add 1 g of Devarda's alloy, 100 mL of recently boiled water, a small lump of paraffin, and 100 mL of 1 N sodium hydroxide. Connect the Kjeldahl flask to the condenser by a suitable trap bulb. Heat the mixture in the flask until 45 to 50 mL of distillate has collected in the receiver. Rinse the condenser, and titrate the boric acid solution with 0.02 N sulfuric acid VS to a pale pink endpoint that persists for 30 seconds. Perform a blank determination, and make any necessary correction. Each mL of 0.02 N sulfuric acid is equivalent to 0.2801 mg of nitrogen. The nitrogen content does not exceed 0.5%.
Formaldehyde—
Transfer 500 mg to a 500-mL iodine flask. Add 250 mL of water, and allow to stand for not less than 2 hours with intermittent shaking. Pipet 0.5 mL of the supernatant into a glass-stoppered test tube, and add 10 mL of
chromotropic acid TS. Stopper the tube loosely, and heat in a boiling water bath for 30 minutes. Cool, and determine the absorbance of the solution at 570 nm, with a suitable spectrophotometer, using a mixture of 0.5 mL of water and 10 mL of
chromotropic acid TS as the blank: the absorbance does not exceed that produced when 0.5 mL of dilute formaldehyde solution (1 in 40,000) is treated in the same manner (0.5% CH
2O).
Assay—
Transfer about 1 g of Oxidized Regenerated Cellulose, previously dried at 90
for 2 hours and accurately weighed, to a 250-mL conical flask. Pipet 10 mL of 0.5 N sodium hydroxide VS into the flask, swirl to dissolve, and add 100 mL of water. Immediately titrate with 0.1 N hydrochloric acid VS to a phenolphthalein endpoint. Perform a blank determination, and note the difference in volumes required. Each mL of the difference in volumes of 0.1 N hydrochloric acid consumed is equivalent to 4.50 mg of carboxyl (COOH).
