Determination of parts per trillion levels of benzoylurea pesticides in groundwater by high-performance liquid chromatography-electrospray ionizationmass spectrometry

A high-performance liquid ch romatography-electrospray ionization mass spec trometry (HPLC-ES-MS) method has been developed for the determination of fi ve benzoylurea pesticides, diflubenzuron, flufenoxuron, hexaflumuron, lufen uron, and triflumuron, in groundwater samples. Initially two atmospheric-pr essure ionization techniques, electrospray (ES) and atmospheric pressure ch emical ionization (APCI), both in positive- and negative-ion modes, were co mpared. Performance data for the method, e. g. recovery, sensitivity, preci sion, and linearity, show the reliability of the method for analysis of wat er samples. The lowest delectable concentrations of the pesticides were bet ween 0.3 and 6.0 ng L-1 and recoveries were from 95 to 104% for water sampl es spiked at 10 ng L-1 ; relative standard deviations were in the range 5 - 15%. The HPLC-ES-MS method was applied to the determination of the live co mpounds in groundwater samples.