Mobile phase variations in thermospray liquid chromatography-mass spectrometry of pesticides.
The effect of four different mobile phase compositions with reversed-phase methanol-water (50:50) + 0.05 M ammonium acetate, methanol-water (50:50) + 0.05 M ammonium formate, acetonitrile-water (50:50) + 0.05 M ammonium acetate and acetonitrile-water (50:50) + 0.05 M ammonium formate were compared in filament-on thermospray liquid chromatography-mass spectrometry for the determination of carbamate and chlorotriazine pesticides. In the positive-ion mode, [M + H]+ and [M + NH4]+ were generally the base peaks for the chlorotriazines and the carbamates, respectively. Depending on the mobile phase used, other adduct ions obtained corresponded to [M + CH3CN + H]+, [M + CH3OH + NH4]+, [M + CH3COONH4 + NH4 - 2H2O]+, [M + CH3CN + NH4]+, [M + CH3COONH4 + H - H2O]+ and the dimer [2M + H]+. In the negative-ion mode, [M - H]- and adducts with the ionizing additive [M + CH3COO]- or [M + HCOO]- were obtained. Other ions for the carbamates carbaryl and oxamyl corresponded to [M - CONHCH3 + CH3COOH]- and [M - CON(CH3)2 + HCOO]-, respectively. The variation of mobile phase composition provides additional structural information in thermospray liquid chromatography-mass spectrometry with no appreciable loss of sensitivity. Applications are reported for the determination of carbamate and chlorotriazine pesticides at the ng/g level in spiked and real soil samples, respectively.
Durand
G
G
Environmental Chemistry Department, CID-CSIC, Barcelona, Spain.
de Bertrand
N
N
Barceló
D
D
D002219:Carbamates; D002853:Chromatography, Liquid; D006843:Hydrocarbons, Chlorinated; D007202:Indicators and Reagents; D007306:Insecticides / Q000032:analysis; D013058:Mass Spectrometry; D010573:Pesticide Residues; D010575:Pesticides / Q000032:analysis*; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis; D012997:Solvents
D002219:Carbamates; D006843:Hydrocarbons, Chlorinated; D007202:Indicators and Reagents; D007306:Insecticides; D010573:Pesticide Residues; D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants; D012997:Solvents