Development and comparison of direct immersion solid phase micro extraction Arrow-GC-MS for the determination of selected pesticides in water

Pesticides are compounds which can affect human, environmental and aquatic system health. Therefore, the detection and determination of these compounds at trace level concentrations is of great importance. In this study selected pesticides out of four classes were investigated as target analytes: Dichlorovos as an insecticide, terbutryn as herbicide, cybutryne from the group of biocides and quinoxyfen as an example of fungicides. A direct immersion solid phase micro extraction (SPME) Arrow-GC?MS method was developed and validated for fully automated microextraction of the target compounds from aqueous samples. In this regard, the most important experimental parameters of the extraction: Extraction time, extraction temperature, pH, ionic strength of the sample and the Arrow type, were studied and optimized. In addition, the developed method was compared with the conventional SPME, regarding sensitivity, relative recovery and precision. The limit of detection values of SPME Arrow were between 0.68 and 544 ng L-1 for dichlorvos and quioxyfen, respectively, and significantly less than similar values obtained from conventional SPME (4.63 and 4400 ng L-1 for the same compounds). For all investigated pesticides, recovery rates ranged between 90 and 116% for the Arrow as well as 85 and 107% for the classical SPME fiber. Relative standard deviations (RSD %) were 4.3?7.8 and 3.5?11.8 for the Arrow and classic SPME, respectively. Also, coefficient of determination (R2) range was within the range of 0.993?0.999 for SPME Arrow and 0.990?0.996 for classic SPME.