A: Infrared Absorption 197F.

B: To 1 mL of a 1 in 10 solution add 5 mL of 1 N sodium hydroxide and 1 drop of cupric sulfate TS, and shake vigorously: a deep blue color develops.

C: To 1 mL of a solution (1 in 100) add 1 mL of 1 N hydrochloric acid, and heat on a steam bath for about 30 minutes. Cool, add 100 mg of hydroxylamine hydrochloride, mix, and add 5 mL of 1 N sodium hydroxide. Allow to stand for 5 minutes, then adjust with 1 N hydrochloric acid to a pH of between 2.5 and 3.0, and add 1 drop of ferric chloride TS: a purplish red color develops.

Test solution: 50 mg per mL, in water.

(Official January 1, 2007)

Potassium biphthalate solution— Dissolve 20.42 g of potassium biphthalate in glacial acetic acid contained in a 1000-mL volumetric flask. If necessary, warm the mixture on a steam bath to achieve complete solution, observing precautions against absorption of moisture. Cool to room temperature, dilute with glacial acetic acid to volume, and mix.

Procedure— Transfer about 400 mg of Dexpanthenol, accurately weighed, to a 300-mL flask fitted to a reflux condenser by means of a standard-taper glass joint, add 50.0 mL of 0.1 N perchloric acid VS, and reflux for 5 hours. Cool, observing precautions to prevent atmospheric moisture from entering the condenser, and rinse the condenser with glacial acetic acid, collecting the rinsings in the flask. Add 5 drops of crystal violet TS, and titrate with Potassium biphthalate solution to a blue-green endpoint. Perform a blank determination, and note the differences in volumes required. Each mL of the difference in volumes of 0.1 N perchloric acid consumed is equivalent to 20.53 mg of C9H19NO4.