Determination of several pesticides with a chemical ionization ion trap detector

A total of one hundred (twenty five each) apple, peach, tomato, and potato samples were analyzed for twelve pesticides and two pesticide metabolites with a slightly modified Luke multiresidue extraction procedure, separation by capillary column gas chromatography with cold on-column injection, and detection by mass chromatography with an ion trap mass spectrometer in the chemical ionization mode (GC/CIMS). Residues of carbaryl, captan, dichloran, dimethoate, methamidophos, phosmet, and tetrahydrophthalimide were found in several samples, with peaches containing the most residues. None of the residues found were above legal tolerances. Recovery studies were performed at the 0.5 ppm fortification level of each pesticide and metabolite at least three times in each of the four crops. Recoveries were between 73 and 120%, with an average coefficient of variation of 11%. Because the computer can be programmed to search for several hundred targeted ions, the use of capillary column GC/CIMS is a promising method that should be explored by regulatory agencies for the analysis of pesticide residues.