Identification—
A:
To about 5 mL of Aerosol spray, collected in a separator, add about 10 mL of water and 3 mL of dilute hydrochloric acid (1 in 2), wash with two 15-mL portions of chloroform, and discard the chloroform washings. Render the solution in the separator alkaline with 5 to 6 mL of ammonium hydroxide, and extract with three 20-mL portions of chloroform, filtering the chloroform extracts through a pledget of cotton previously moistened with chloroform. Evaporate the combined chloroform extracts with the aid of gentle heat to dryness, and dry the residue in vacuum over silica gel for 24 hours: a potassium bromide dispersion of the lidocaine so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of
USP Lidocaine RS.
B:
To about 2 mL of Aerosol spray, collected in a test tube, add 10 to 15 drops of
cobaltous chloride TS, and shake for about 2 minutes: a bright green color develops, and a fine precipitate is formed (lidocaine).
C:
To about 2 mL of Aerosol spray, collected in a test tube, add 5 mL of water, 1 mL of 2 N nitric acid, and 3 mL of
mercuric nitrate TS: a light yellow color develops (lidocaine).
Assay—
Accurately weigh 1 Aerosol container and actuator. Transfer a counted number of not less than 10 doses to a 125-mL conical flask by carefully discharging the doses in a manner such as to avoid loss of material, and take precautions to protect the specimen from absorption of atmospheric moisture. Accurately weigh the container and actuator to obtain the specimen weight. To the specimen add 20 mL of chloroform, mix, and add 10 mL of dioxane and 2 drops of
crystal violet TS. Titrate with 0.1 N perchloric acid in dioxane VS to a blue endpoint. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 23.43 mg of C
14H
22N
2O.
61
—
It meets the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa.