HPLC Determination of Physostigmine in the Presence of Degradation Products and Preservatives

Abstract

A reversed phase, ion-pairing liquid chromatographic method was developed for the analyses of physostignine-containing pharmaceuticals in the presence of its decomposition products, eseroline and rubreserine, and preservatives methyl- and propylparaben. A satisfactory resolution for the peaks for these compounds was obtained with this isocratic method. All peaks were eluted in less than 12 minutes. The capacity factors of these compounds ranged from 1.50 to 9.27. The linearity and repeatability of this method were examined. The CV's of retention times of all compounds ranged from 0.87 to 1.81%, and the CV of physostignine peak areas was 2.17%.A gradient-elution, ion-pairing HPLC method was developed for the analyses of pharmaceutical preparations containing physostigmine, eseroline, rubreserine, and benzyl alcohol as an antibacterial agent. The capacity factors of these compounds ranged from 2.75 to 10.51. The CV of retention times ranged from 0.79 to 1.27%. This method is also suitable for the simultaneous quantitation of benzyl alcohol.