Separation and determination of quaternary ammonium compounds by high-performance liquid chromatography with a hydrophilic polymer column and conductometric detection

An HPLC method has been developed for separation and determination of long alkyl chain quaternary ammonium compounds. A column packed with a hydrophil ic polymer packing, Shodex Asahipak GF-310 HQ, and a water-acetonitrile mix ture containing 4,4'-bipyridyl and hydrochloric acid were used to depress h ydrophobic adsorption of the quaternary ammonium compounds and increase the sensitivity of the conductometric detection with a micromembrane suppresso r. Dodecyltrimethylammonium, cetyltrimethylammonium, tetradecyldimethylbenz ylammonium and stearyltrimethylammonium ions can be completely separated fr om one another and quantified at 0.1 nmol level. (C) 1999 Elsevier Science B.V. All rights reserved.