Solid phase microextraction for organochlorine pesticidesin water samples using MWCNTs-doped polypyrrole coated on steel fiber before determination by gas chromatography electron capture detector

The analysis of organochlorine pesticides (OCPs) residues has received an increasing attention in the last decades. The solid-phase microextration (SPME) is a convenient and fast analytical method, which has been widely used for the determination of volatile and semivolatile organic compounds in aqueous samples. In this study, the multiwalled carbon nanotubes/polypyrrole composite (MWCNTs- PPy) coated on steel fiber was used for extraction OCPs from water samples by the SPME technique. The effects of various parameters on the efficiency of SPME process such as extraction time, extraction temperature, ionic strength, desorption time, and desorption temperature were studied. Under optimized conditions, the detection limits for the OCPs varied between 0.051 and 0.39 pg mL^-1, the interday and intra-day relative standard deviations for various OCPs using a single fiber were 6.5-11.5% and 3.6-11.5, respectively. The linear ranges varied between 0.001 and 1 ng mL^-1. The proposed method was successfully applied to the analysis of ground water samples with the recoveries from 86 to 110%