A single-step procedure for the extraction and derivatization of carboxylic pesticides from aqueous samples is described. The acidic compounds, including phenoxy herbicides, were extracted from aqueous samples using tetrahexylammonium hydrogensulphate as a catalyst and were subsequently derivatized with pentafluorobenzyl bromide to volatile stable and electron-capturing derivatives. Analysis was performed by gas chromatography with electron-capture detection combined with negative-ion chemical ionization mass spectrometry. The recovery of the compounds was 108 ± 8%. Detection limits were typically 0.05 μg/1, using mass unit resolution. Highly contaminated samples required increased resolution (1000 ≤ Rf≤ 4000) for reduced chemical background and enhanced selectivity for detection at low-ppb levels. The method was applied to the determination of some phenoxycarboxylic pesticides in surface water and in blood samples. © 1993.
Meiring, H. D., den Engelsman, G., & de Jong, A. P. J. M. (1993). Determination of polar pesticides by phase-transfer catalysed derivatization and negative-ion chemical ionization gas chromatography-mass spectrometry. Journal of Chromatography A, 644(2), 357–365. https://doi.org/10.1016/0021-9673(93)80720-S