Studies on Multiresidue Determination of Pesticides in Fruits and Vegetables by Gas Chromatography/Mass Spectrometry

CHAO-HONG LIU¹, CHUN-LUNG CHENG¹, SHUR-JYUAN SHIH¹, GOW-CHIN YEN² AND SHIN-SHOU CHOU¹

1. National Laboratories of Foods and Drugs, Department of Health, Executive Yuan Nankang, Taipei 115, ROC.
2. Graduate Institute of Food Science, National Chung-Hsing University Taichung, Taiwan 402, R.O.C.

 ABSTRACT

   A multiresidue method using gas chromato-graphy/mass spectrometry (GC/MS) was evaluated for the determination of several pesticides in fruits and vegetables. The pesticides were extracted using a slightly modified Luke multiresidue procedure, separated by capillary column gas chromatography and detected by mass chromatography with quadrupole mass spectrometer in the electron impact mode. Recovery studies of chlorpyrifos, diazinon, endosulfan, fenarimol, fenvalerate, folpet, iprodione, malathion, methamidophos, phosmet and procymidone were performed at the 0.5 ppm spike level in cherry tomatoes, chin-chian pe-tsai, Chinese cabbages, kidney beans and oranges. Recoveries were between 64.6 and 124.6%, with the exception of methamidophos which produced interference due to the constituents of the samples. Coefficients of variation ranged between 0.3 and 17.6%, with an average of 5.3%. The estimated limits of detection of the pesticides (except methamidophos) in the crops were at the 0.1 ppm level. Because the mass spectrometer is capable of achieving higher levels of molecular specificity as compared to the traditional GC detectors and can be programmed to search for several hundred target ions simultaneously, GC/MS may be a promising method for the use of regulatory agencies with which to monitor pesticide residues in daily food products.

Key words: Pesticides, residues, multiresidue method (MRM), GC/MS