Sensitive determination of carbamates in fruit and vegetables by a combination of solid-phase extraction and dispersive liquid-liquid microextraction prior to HPLC

摘要

We report on a new method for sample pretreat-ment. It is based on solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME) and was applied to the determination of carbamates in apple and cucumber. The carbamates carbofuran, carbaryl, and pirimi-carb were first extracted from samples by SPE. The analytes were then eluted from the sorbent with acetonitrile, and the DLLME technique was then applied to the resulting eluate. Finally, the analytes in the extraction solvent were determined by HPLC. Several parameters affecting the SPE-DLLME process were optimized. The new method provides enrichment factors that range from 5,400 to 7,650, Calibration plots are linear in the range from 0.25 to 100 μg kg~(-1) for carbofuran and carbaryl, and from 0.10 to 100 μg kg~(-1) for pirimicarb, with correlation coefficient (r~2) ranging from 0.9980 to 0.9997. The limits of detection range from 5 to 60 pg kg~(-1) (at S/N=3). The method was successfully applied to the extraction and sensitive determination of carbamates in apple and cucumber samples.