Confirmation of organophosphorus pesticide residues in food applying gas chromatography/mass spectrometry with chemical ionization and pulsed positive negative detection

A confirmatory technique for residue analysis of organophosphorus pesticides in food samples applying gas chromatography/mass spectrometry is described. The use of capillary columns is essential to achieve the separation of the great number of pesticides in use. Chemical ionization with the simultaneous recording of positive and negative ions results in the highest detection sensitivity for all 72 compounds. A selection of three ions was made for each pesticide and the parameters were optimized to gain highest detection sensitivity. The method was proved with food samples from the daily routine control.