SENSITIVE AND SPECIFIC ASSAY OF TERTIARY AMINE DRUGS WITH PHTHALIC ANHYDRIDE

Document Type : Original Article

Authors

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Assiut University, Assiut

Abstract

The reaction of tertiary amines with phthalic anhydride/acetic anhydride mixture was studied and developed into a sensitive assay for the amines. The method is based on the condensation of the two anhydrides under the catalytic effect of the tertiary amine function, either free or in the form of a salt. The condensation product had a lmax at 302 nm for all the drugs tested with apparent molar absorptivitis in the range 5.79 x 104- 1.08 x 105. Absorption Versus concentration was found linear up to about 6 mcg/ml for all drugs studied. The method has been applied for the analysis of certain tertiary amine drugs belonging to different pharmacological groups e.g. pilocarpine nitrate, butethamat citrate, atropine sulphate, bietamiverine dihydrochloride, codeine phosphate and toclase citrate in pure form as well as in pharmaceutical preparations without prior separation and with good accuracy (100 38%), recoveries and precision (SD ± 0.41).