Infrared Determination of Piloearpine in Ophthalmic Solutions

Abstract

Official methods for piloearpine salts are aqueous and nonaqueous titrations that lack specificity. In the proposed method, piloearpine is extracted from the sample with chloroform and determined by infrared spectrophotometry with the absorbance maximum of 9 μ. Identity of the piloearpine is confirmed by comparing spectra of sample and standard between 5 and 11 μ. Recoveries of piloearpine from simple aqueous solutions of the nitrate ranged from 99 to 104%. Analysis of 9 commercial products declaring 0.5—4% piloearpine salt showed good precision between duplicates. Further study is recommended.