Identification of organophosphorus insecticides and their hydrolysis products by liquid chromatography in combination with UV and thermospray-mass spectrometric detection.
Liquid chromatography with ultraviolet detection (LC-UV) and positive and negative ion mode (PI and NI, respectively) thermospray LC-mass spectrometry (LC-MS) were used for the analysis of the organophosphorus pesticides azinphos-methyl, diazinon and parathion-methyl and their corresponding breakdown products obtained after basic hydrolysis (pH 7-11). LC analysis was performed in the reversed-phase mode using methanol-water (80:20) or methanol-water (70:30) + 0.1 M ammonium acetate for LC-UV or LC-MS, respectively. By employing NI thermospray LC-MS the identification of p-nitrophenol, showing the [2M-H]- ion as the base peak, was feasible and confirmed the LC-UV chromatogram at 220 nm. When the PI mode was used, [M + NH4]+ and [M + H]+ ions were obtained as base peaks for azinphos-methyl and diazinon, respectively. The degradation rates varied from diazinon, which showed no degradation during a period of ten days, to azinphos-methyl and parathion-methyl, for which degradation occurred rapidly when the pH was increased from 7 to 11.
Farran
A
A
Department of Chemical Engineering, ETSEIB, Barcelona, Spain.
De Pablo
J
J
Barceló
D
D
D001387:Azinphosmethyl / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D003976:Diazinon / Q000032:analysis*; D006868:Hydrolysis; D007306:Insecticides / Q000032:analysis*; D013058:Mass Spectrometry; D008743:Methyl Parathion / Q000032:analysis*; D010278:Parathion / Q000031:analogs & derivatives*; D013056:Spectrophotometry, Ultraviolet
D007306:Insecticides; D001387:Azinphosmethyl; D008743:Methyl Parathion; D010278:Parathion; D003976:Diazinon