Abstract: A multiresidue analytical method was developed for the determination of 156 pesticides in concentrated fruit and vegetable juices using liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). The pesticide residues were extracted from the samples by acetonitrile containing 1% acetate acid, cleaned-up by a Waters Sep-Pak Vac cartridge, eluted with 25 mL acetonitrile-toluene (3∶1, v/v) and concentrated with a rotary evaporator. The sample was redissolved in the acetonitrile-water (3∶2, v/v), then analyzed using LC-MS/MS in multiple reaction monitoring (MRM) mode via positive electrospray ionization with an Agilent ZORBAX SB-C18 column as the analytical column. The method was validated at two fortification levels in five fruit and vegetable juices, orange, apple, grape, cabbage and carrot juices. The validation results were as follows: The overall recoveries were from 57.2% to 122.7% with the relative standard deviations (RSDs) of 0.9%-19.8%, and the limits of detection (S/N=3) and the limits of quantification (S/N=10) were 0.10-56.77 μg/kg and 0.33-189.23 μg/kg, respectively. The results demonstrated that this method is simple, rapid and characterized with acceptable sensitivity and accuracy to meet the requirements of the multiple pesticide residue analysis. This method is applicable to confirm 156 pesticide residues in the above five juices.

Key words: concentrated fruit and vegetable juices , multiple pesticide residues, QuEChERS method, liquid chromatography-tandem mass spectrometry (LC-MS/MS)