| Solid-phase microextraction(SPME) is a simple and effective adsorption and desorption technique, which eliminates the need for solvents or complicated apparatus, for concentrating volatile or semi-volatile compounds in liquid samples or headspace. SPME is compatible with analyte separation and detection by gas chromatography and high-performance liquid chromatography, and provides linear results for wide concentration of analytes. By controlling the polarity and thichness of the coating on the fibers, maintaining consistent sampling time, and adjusting other extraction parameters, an analyte can ensure highly consistent, quantifiable results for low concentration analytes.Organochlorine pesticides such as Hexachlorobenzene (HCB) and diphenyl-dichloro-trchloroetane(DDT) and its metabolites are one of the most dangerous pollutants because of their high liposolubility and tend to bioaccumulate along the food chain involving a wide range of trophic levels. The increasing risks to human health, generated by the widespread use of organochlorine pesticides in our environment is well established. The determination of organochlorine pesticides is of major importance.In this study, firstly, the operation parameters of GC-ECD were optimized , HCB, DDT and its metabolites in environmental water samples were analyzed by head space solid-phase microextraction (HS-SPME) coupled with gas chromatographic electron capture detection (GC-ECD). The three different SPME fibers were used for comparing the recoveries in determining HCB, DDT and its metabolites. All the HS-SPME analytical parameters including salinity, temperture, adsorbtion and desorption time were optimized. The results show that both the detection limits and relative recoveries of HS-SPME are better than the traditional liquid-liquid extraction (LLE). The PDMS fiber is the best for the extractions of HCB, DDT and its metabolites among the three tested fibers.
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