Determination of benzoylphenylurea insecticides in pome fruit and fruiting vegetables by liquid chromatography with diode array detection and residue data obtained in the dutch national monitoring program

Abstract

Liquid chromatography (LC) with diode array detection was used to screen for residues of the benzoylphenylurea (BPU) insecticides diflubenzuron, teflubenzuron, triflumuron, hexaflumuron, lufenuron, chlorfluazuron, flufenoxuron, and flucycloxuron in pome fruit and fruiting vegetables. The general sample preparation and extraction method for our gas chromatography (GC) and LC multiresidue methods scheme was used as a starting point. Crop samples were extracted with acetone and partitioned into dichloromethane-petroleum ether. Solid-phase extraction on aminopropyl-bonded silica cartridges was used to separate the BPU insecticides from major interfering sample components. LC separations were performed on a reversed-phase column, with an acetonitrile-water gradient as mobile phase. A diode array detector was used to monitor the insecticides at 260 nm and to acquire spectral information for additional confirmation. Recoveries and repeatability data were collected for 7 benzoylphenylurea insecticides in mushroom, Chinese cabbage, apple, and cucumber samples representing different commodity groups at one spike level. The limits of detection ranged from 20 to 50 μg/kg for all BPU insecticides studied and is dependent on the matrix-pesticide combination. A confirmation method for BPU insecticides based on GC-mass spectrometry (ion-trap detector) of the characteristic degradation products is also reported. Residues of BPU insecticides in pome fruit and fruiting vegetables found during our Dutch pesticide residue monitoring program in 1995-1998 are presented.