A: Infrared Absorption 197K.

B: Ultraviolet Absorption 197U—

C: A solution (1 in 100) responds to the tests for Chloride 191.

Solvent— Prepare a mixture of chloroform and methanol (9:1).

Standard preparations— Dissolve a quantity of USP Propoxycaine Hydrochloride RS in Solvent, and dilute quantitatively, and stepwise if necessary, with Solvent to obtain a solution containing 0.5 mg per mL. Dilute quantitatively with Solvent to obtain Standard preparations having the following compositions:

Test preparation— Dissolve an accurately weighed quantity of Propoxycaine Hydrochloride in Solvent to obtain a solution containing 50 mg per mL.

Procedure— Apply separately 5 µL of the Test preparation and 5 µL of each Standard preparation to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Position the plate in a chromatographic chamber, and develop the chromatograms in a solvent system consisting of a mixture of chloroform, methanol, and isopropylamine (96:2:2) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate, with the aid of warm circulating air. Examine the plate under short-wavelength UV light, and again after exposing the plate to iodine vapors for a few minutes and spraying it with 7 N sulfuric acid. In each instance, compare the intensities of any secondary spots observed in the chromatogram of the Test preparation with those of the principal spots in the chromatograms of the Standard preparations: no secondary spot is more intense than the principal spot obtained from Standard preparation A (0.5%), and the sum of the intensities of all secondary spots obtained from the Test preparation does not exceed 1.0%.