Quantitative determinations of two decongestants and an antihistamine in combination using paired ion high-pressure liquid chromatography.

A single method for the quantitative determinations of three active ingredients, phenylephrine hydrochloride, phenylpropanolamine hydrochloride, and brompheniramine maleate, and one inactive ingredient (sodium benzoate) in a commercial product for colds is reported. The method is based on paired ion high-pressure liquid chromatography using 1-heptanesulfonic acid as the counterion. It is accurate and precise. The relative standard deviations based on six readings are reported. This method is sensitive; less than 1 microgram of each ingredient can be assayed. The peak area of each ingredient is related to its concentration.