TRACE DETERMINATION OF HERBICIDES IN ESTUARINE WATERS BY LIQUID-CHROMATOGRAPHY HIGH-FLOW PNEUMATICALLY ASSISTED ELECTROSPRAY MASS-SPECTROMETRY

High-flow pneumatically assisted electrospray (ESP) was applied to the characterization of triazine (atrazine, simazine, ametryne, cyanazine , deethylatrazine and deisopropylatrazine), phenylurea (chlortoluron, isoproturon, diuron, linuron and diflubenzuron) and other priority her bicides (alachlor, metorachlor). In LC-ESP-MS the [M + Na](+) ion was used as the base peak in most cases, with the exception of chlorotriaz ines, which showed [M + H](+) as the base peak. When LC-TSP-MS was use d, [M + H](+) was the base peak for many of the pesticides, with the e xception of linuron and diflubenzuron, which showed [M + NH4](+) as th e base peak. The ESP results were compared with those obtained with th ermospray (TSP). LC-TSP-MS offered greater sensitivity for triazines t han phenylurea herbicides, whereas the use of LC-ESP-MS offered an enh ancement in sensitivity for phenylurea herbicides. As regards the frag mentation obtained using both techniques, ESP offered a considerable a mount of structural information for the different chlorotriazines stud ied when the extraction voltage was increased from 20 to 40 V. Liquid- liquid extraction with dichloromethane was used for the trace enrichme nt of the different herbicides in estuarine water samples from the Elo rn river (France). The presence of the different triazine metabolites, atrazine, simazine, metolachlor, isoproturon and diuron was confirmed by both LC-MS techniques.