DETERMINATION OF THE PESTICIDES DIFLUBENZURON AND CLOFENTEZINE IN PLUMS, STRAWBERRIES AND BLACK-CURRANT-BASED FRUIT DRINKS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ATMOSPHERIC-PRESSURE CHEMICAL-IONIZATION MASS-SPECTROMETRY

A high performance liquid chromatographic/atmospheric pressure chemica l ionization-mass spectrometric (HPLC/APCI-MS) method has been develop ed for the determination of the pesticides diflubenzuron (1-(4-chlorop henyl)-3-(2,6-difluorobenzoyl)urea) and clofentezine (3,6-bis(2-chloro phenyl)-1,2,4,5-tetrazine) in plums, strawberries and blackcurrant-bas ed fruit drinks, Samples were homogenized with acetone, extracted into dichloromethane + cyclohexane and cleaned-up by high performance gel permeation chromatography. HPLC was performed on an ODS column with me thanol+water at 1 mL/min. Detection was by negative-ion selected-ion m onitoring APCI-MS, Comparison of response with solvent and matrix-matc hed standards showed some ehancement of response for the latter, and t hese standards were consequently used for quantification. The calibrat ion was Linear over the range 0.05-0.50 ng/mu L in all three matrices. The mean overall recovery of diflubenzuron and clofentezine from spik ed extracts (0.086 mg/kg) in all three matrices was 76% and 70% respec tively with relative standard deviations of 15% and 12% respectively ( n=12), The limit of detection was both compound and commodity dependen t and ranged from 0.01-0.05 ng/mu L, equivalent to 0.003-0.014 mg/kg i n the crop.