Determination of pesticides by on-line trace enrichment - Reversed-phase liquid chromatography - Diode-array detection and confirmation by particle-beam mass spectrometry

A group of pesticides has been determined by liquid chromatography with diode-array detection (DAD). The coupling of a particle-beam (PB) mass spectrometer to the outlet of the DAD enabled the identities of the pesticides to be confirmed from mass spectra obtained by electron impact ionization. On-line trace enrichment of 200 mL of sample with a PLRP-S precolumn enabled most pesticides to be determined in real samples at levels between 0.2 and 5 mu g L(-1) and with limits of detection (LOD) between 0.05 and 0.5 mu g L(-1) In the analysis of real samples, one of the pesticides studied was determined by DAD and its identity was confirmed by comparison of PB mass spectra. The use of PB-MS also enabled the detection of non-target compounds.