Simple and rapid determination of benzoylphenylurea pesticides in river water and vegetables by LC-ESI-MS

Liquid chromatography with electrospray mass spectrometry (LC-ESI-MS) instrumentation equipped with a single quadrupole mass filter has been used to determine several benzoylphenylurea insecticides (diflubenzuron, triflumuron, hexaflumuron, lufenuron and flufenoxuron). Chromatographic and MS parameters were optimised to obtain the best sensitivity and selectivity for all pesticides. Solid-phase extraction (SPE) using C-18 cartridges was applied for preconcentration of pesticide trace levels in river water samples. Recoveries of benzoylphenylurea pesticides from spiked river water (0.01 and 0.025 mu g L-1) were between 73 and 110% and detection limits were between 3.5 and 7.5 ng L-1. The applicability of the method to the determination of benzoylphenylurea insecticides in spiked cucumber, green beans, tomatoes and aubergines was evaluated. Samples were extracted into dichloromethane without any clean-up step. The limits of detection ranged from 1.0 to 3.2 ng mL(-1) (0.68 and 2.13 mu g kg(-1) in the vegetable samples). Mean recoveries ranged from 79 to 114% at spiking levels of 0.0 1 and 0.03 mg kg(-1). The method was applied to determine traces of benzoylphenylureas in both river water and vegetable samples with precision values lower than 10%. Interferences due to the matrix effect were overcome using matrix-matched standards.