ION-PAIR REVERSED-PHASE HIGH-PRESSURE LIQUID-CHROMATOGRAPHY OF COUGH-COLD SYRUPS .1. PSEUDOEPHEDRINE HYDROCHLORIDE, BROMPHENIRAMINE MALEATE, AND DEXTROMETHORPHAN HYDROBROMIDE

Pseudoephedrine hydrochloride (I), brompheniramine maleate (II), and dextromethorphan hydrobromide (III) in a cough‐cold syrup were separated and determined by ion‐pair reversed‐phase high‐pressure liquid chromatography. The separation was carried out using a μBondapak C18 column (30 cm X 3.9 mm i.d.) and a mobile phase of acetonitrile‐water‐acetic acid (40:60:1) with 0.01 N 1‐octanesulfonic acid sodium salt and 0.05 N potassium nitrate. Detection was accomplished using a UV detector at 265 nm for I and II; III was monitored at 280 nm. Concentration versus peak height plots in the ranges of 0.37‐1.9 mg/ml for I,0.025‐0.126 mg/ml for II, and 0.125‐0.625 mg/ml for III were linear. Ten consecutive injections of a mixture gave a percent relative standard deviation of <1% for all three components. Average recoveries from laboratory‐prepared samples were 100.5% for I, 100.9% for II, and 100.1% for III. No precolumn cleanup was necessary, and the chromatogram was complete in 16 min. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company