Behaviour of carbamate pesticides in gas chromatography and their determination with solid-phase extraction and solid-phase microextraction as preconcentration steps

This work reports a study of the chromatographic behaviour of seven carbamate pesticides (aldicarb, carbetamide, propoxur, carbofuran, carbaryl, methiocarb, and pirimicarb) by gas chromatography-mass spectrometry (GC-MS). Variables such as injector temperature, solvent, injection mode, and the degree of ageing of the chromatographic column were studied. One of the aims of this work was to achieve a controlled decomposition of carbamates by a solid-phase microextraction (SPME) preconcentration step with a polyacrylate fibre in order to obtain reproducible chromatographic signals of the degradation products. Optimisation of the SPME process was accomplished by means of experimental design. Several methods using ultrapure water were developed with different preconcentration configurations: SPME-GC-MS, SPE followed by SPME-GC-MS, and SPE plus GC-MS. For all the pesticides studied, method detection limit (MDL) values below 0.1 microg L-1 were reached in at least one of the proposed configurations.