Multiresidue determination of pyrethroid pesticides in fruit juices by matrix solid-phase dispersion and gas chromatography-negative chemical ionization-mass spectrometry

A rapid method based on matrix solid-phase dispersion was developed for the determination of ten pyrethroid pesticides in commercial juices.Meanwhile,negative ion structure and fracture mechanism of these pesticides of negative chemical ionization mass spectrometry were evaluated.The group of pesticides was added to juice and blended with neutral alumina,the mixture was packed into disposable filtration column,this column was tandem with florisil as cleaning and was eluted with ethyl acetate.The analysis of samples was accomplished using gas chromatography with negative chemical ionization mass spectrometric detection(GC-NCIMS) in the selected ion monitoring mode(SIM),and with PCB103 as internal standard.Recovery studies were performed at 50 and 250 μg/kg fortification levels for each pesticide,and the average recoveries ranged from 86.7 to 114.8% with a relative standard deviation between 1.9% and 14.1% for the different pesticides. The detection limit of the method was less than 1.0 μg/kg for most of pesticides except for the permethrin.The developed method was linear over the range assayed,10～500μg/kg,with correlation coefficients 0.997.The proposed method was applied to the analysis of these compounds in commercial juice samples.At least two pesticides was found in most of the samples.