DETERMINATION OF PIRIMIPHOS-METHYL IN PASTA BY GAS CHROMATOGRAPHY/CHEMICAL IONIZATION MASS SPECTROMETRY

A method for the determination of pirimiphos-methyl residues in pasta has been developed. The pesticide was extracted from pasta using the Luke procedure modified for low moisture, nonfatty food products. The extracts were analyzed by capillary column gas chromatography using an ion trap mass spectrometer in the chemical ionization mode as the detector. Quantification was performed using fluorene as the internal standard. The limit of detection was 0.005 ppm. Recoveries from spaghetti were 83.0% at the 0.100 ppm level and 93.3% at the 0.010 ppm level. Of 48 spaghetti samples analyzed, 38 contained detectable residues between trace (>0.005 ppm) and 0.180 ppm. Electron ionization (EI) was used to confirm residues as low as 0.016 ppm in more concentrated extracts.