On-line ion-pair solid-phase extraction-liquid chromatography-mass spectrometry for the analysis of quaternary ammonium herbicides

An ion-pair on-line solid-phase extraction procedure using C-8 extraction d isks, suitable for liquid chromatography-mass spectrometry analysis is deve loped to determine quaternary ammonium herbicides (quats) in water samples. The separation of these compounds was performed using ion-pair chromatogra phy with heptafluorobutyric acid (15 mM, pH 3.3) and acetonitrile gradient elution. Detection was carried out using a quadrupole mass spectrometer. Wa ter sample volumes up to 50 ml can be preconcentrated with recoveries highe r than 70%. Good precision and accuracy (day-to-day and run-to-run) were ob tained and the detection limits ranged from 6 to 85 ng l(-1). The proposed on-line ion-pair solid-phase method enables compliance with European Commun ity directives for drinking waters (100 ng l(-1)). (C) 2000 Elsevier Scienc e B.V. All rights reserved.