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

A high-performance liquid ch romatography-electrospray ionization mass spectrometry (HPLC-ES-MS) method has been developed for the determination of five benzoylurea pesticides, diflubenzuron, flufenoxuron, hexaflumuron, lufenuron, and triflumuron, in groundwater samples. Initially two atmospheric-pressure ionization techniques, electrospray (ES) and atmospheric pressure chemical ionization (APCI), both in positive- and negative-ion modes, were compared. Performance data for the method, e. g. recovery, sensitivity, precision, and linearity, show the reliability of the method for analysis of water samples. The lowest delectable concentrations of the pesticides were between 0.3 and 6.0 ng L-1 and recoveries were from 95 to 104% for water samples 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 compounds in groundwater samples.