High-performance liquid chromatographic/mass spectrometric and high-performance liquid chromatographic/tandem mass spectrometric analysis of carbamate pesticides

Abstract

The thermospray ionization mass spectra of selected carbamate pesticides were obtained using both single-stage and triple-stage quadrupole mass spectrometry in conjunction with high-performance liquid chromatography. With the use of the single-quadrupole mass spectrometer and ammonium acetate as the mobile phase, enhanced sensitivity for the analytes of interest was obtained by monitoring the relatively intact [M + 1]+ or [M + 18]+ adduct ions. Further structural characterization of the carbamates was not readily obtainable owing to the lack of diagnostic bond cleavages. The single-stage quadrupole analyses were therefore complemented by triple-stage quadrupole analyses. Here, collisionally activated daughter ion spectra exhibited structure-specific fragmentations. In addition, the enhanced selectivity and specificity provided by tandem mass spectrometry allowed use of the technique as a rapid screening tool for carbamates without the need for the chromatographic separation step.

Analysis of chlorotriazines and their degradation products in environmental samples by selecting various operating modes in thermospray HPLC/MS/MS

“…This will be very valuable since the identification of unknown pesticide metabolites formed during degradation processes can be unequivocally identified. These difficulties have prompted the need of using HPLC in combination with tandem MS which has been applied to the determination of chlorotriazine pesticides (Voyksner, 1987;Voyksner et al, 1990) and organophosphorus (Betowski and Jones, 1988) and carbamate insecticides (Chiu et al, 1989), all of which testify to an increasing use of tandem MS for screening different groups of pesticides in environmental matrices.…”

Mass spectrometric analysis of nitrogen- and phosphorus-containing pesticides by liquid chromatography-Mass Spectrometry

“…At present, TSP is most widely used because of its sensitivity as compared to PB and its compatibility with conventional high-performance liquid chromatography (HPLC) systems as compared to ESI. The lack of structural information obtained from TSP mass spectra can readily be overcome, for example, by variation of the gas-phase and vaporizer temperature to induce controlled chemical reactions during TSP vaporization and ionization [7], the use of external ionization media and tandem mass spectrometry techniques [19], repeller-induced fragmentation [20], additional cluster ions formed with solvent or additive molecules, and by using the complementary information of positive and negative ion spectra [7,14,15]. These techniques provide adequate structural information for the identification and confirmation of pesticides in environmental samples [6,14].…”

Ion formation of N-Methyl carbamate pesticides in thermospray mass spectrometry: The effects of additives to the liquid chromatographic eluent and of the vaporizer temperature

“…The validity of this statement is curroborated by the fact that reported mass spectra of the carbamates, as obtained by the application of var ious ionization conditions (i.e., conven tional chemical ionization (Cl) [il -l7] and LCjMS interfacing . [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]), show large differences. This is illustrated by the data for carbofuran which are summarized in Table 1.…”