engleski

Optimisation of a multi-residue method for trace determination of persistent organochlorine pollutants in soil

A high resolution gas chromatographic (GC) method with electron capture or ion trap mass spectrometric detection was optimized for simultaneous determination of 35 persistent organochlorine pollutants in soil. The method was validated for the analysis of 15 organochlorine pesticides and 20 polychlorinated biphenyl (PCB) congeners. Soil samples of different pedological characteristics were fortified with a mixture of target analytes at the mass fraction levels of about 1 and 50 μg/kg of each compound. Extraction of air-dried soil samples was accomplished by a microwave-assisted extraction (MAE) procedure using a 1:1 acetone/n-hexane mixture as extracting solvent. The extracts were purified either by washing with concentrated sulphuric acid (not applicable for determination of endrin and dieldrin due to their sensitivity to concentrated mineral acids) or by solid-phase extraction (SPE) on the commercially available Florisil (1 g, 6 mL) SPE columns. The GC analysis was performed on two different fused silica capillary columns (60 m x 0.25 mm i.e., film thickness 0.25 μm). The Rtx-CLPesticides column enabled an efficient separation of all 35 analytes in less than 50 min, while on the Rtx-5 column 2, 4-DDT and PCB-114 co-eluted chromatographically. Method performance parameters including the extraction efficiency of organochlorine pollutants from different soils and under different MAE conditions, the efficiency of purification of soil extracts for analysis of target analytes and the effects of possibly co-eluted soil matrix components on the selectivity and sensitivity of GC analysis were investigated in details.

Organochlorine pesticides; polychlorinated biphenyls; analysis in soil

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