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

Abstract An HPLC method has been developed for separation and determination of long alkyl chain quaternary ammonium compounds. A column packed with a hydrophilic polymer packing, Shodex Asahipak GF-310 HQ, and a water–acetonitrile mixture containing 4,4′-bipyridyl and hydrochloric acid were used to depress hydrophobic adsorption of the quaternary ammonium compounds and increase the sensitivity of the conductometric detection with a micromembrane suppressor. Dodecyltrimethylammonium, cetyltrimethylammonium, tetradecyldimethylbenzylammonium and stearyltrimethylammonium ions can be completely separated from one another and quantified at 0.1 nmol level.