Abstract

The isocratic separation and simultaneous estimation of acetaminophen, pseudoephedrine hydrochloride, guaifenesin and dextromethorphan hydrobromide in bulk and pharmaceutical dosage forms using the technique of packed column supercritical fluid chromatography (pcSFC), has been described. Method development was based on the measurement of retention times as a function of parameters of pressure, temperature and modifier composition. An arbitrary mixture of the 4 drugs was base-line resolved on a Hypersil-Phenyl (250 x 4.6 mm) 5 pm column with a ternary mobile phase of carbon dioxide modified with 14.29% (v/v) methanol containing 1% methylamine. Detection was absorptimetric at 210 nm. The method has been fully validated and a full statistical evaluation included. Application of the method to real-time samples revealed no interferences from excipients. A comparison of the method with an HPLC method for the same assay, which appeared in literature, validated the recent proposition that pcSFC is not only a viable but also a superior alternative to HPLC for pharmaceutical analysis.