Quantitative analysis of parathion and parathion-methyl by combined capillary column gas chromatography negative ion chemical ionization mass spectrometry

Deuterium-labelled parathion and parathion-methyl were prepared and used as internal standards in an analytical procedure for precise determinations of parathion and parathion-methyl in complex matrices. The use of negative chemical ionization mass spectrometry in the selected ion monitoring mode gave an extremely high sensitivity and selectivity for these compounds. Calibration curves showed linearity with a correlation of 99.9% in the investigated region (0.5–500 pg) and detection limits could generally be expanded to the ppt (ng/kg) level. The procedure was applied for quantitative determination of the parathions in a marine sediment near a chemical deposit.