Chemometric assisted ultrasound leaching-solid phase extraction followed by dispersive-solidification liquid–liquid microextraction for determination of organophosphorus pesticides in soil samples

Abstract

Ultrasound leaching-solid phase extraction (USL-SPE) followed by dispersive-solidification liquid–liquid microextraction (DSLLME) was developed for preconcentration and determination of organophosphorus pesticides (OPPs) in soil samples prior gas chromatography–mass spectrometry analysis. At first, OPPs were ultrasonically leached from soil samples by using methanol. After centrifugation, the separated methanol was diluted to 50mL with double-distillated water and passed through the C18 SPE cartridge. OPPs were eluted with 1mL acetonitrile. Thus, 1mL acetonitrile extract (disperser solvent) and 10µL 1-undecanol (extraction solvent) were added to 5mL double-distilled water and a DSLLME technique was applied. The variables of interest in the USL-SPE-DSLLME method were optimized with the aid of chemometric approaches. First, in screening experiments, fractional factorial design (FFD) was used for selecting the variables which significantly affected the extraction procedure. Afterwards, the significant variables were optimized using response surface methodology (RSM) based on central composite design (CCD). Under the optimum conditions, the enrichment factors were 6890–8830. The linear range was 0.025–625ngg−1 and limits of detection (LODs) were between 0.012 and 0.2ngg−1. The relative standard deviations (RSDs) were in the range of 4.06–8.9% (n=6). The relative recoveries of OPPs from different soil samples were 85–98%.