Gas chromatographic determination of organochlorine and organophosphorus pesticides in human fluids using solid phase microextraction

Abstract

This paper explores the feasibility of developing procedures based on solid phase microextraction (SPME) for the determination of pesticides in human body fluids, including serum and urine samples. The advantages of SPME procedures could greatly help in sample treatment reduction that is highly recommendable in biological monitoring for pesticides. Two procedures based on direct immersion SPME and GC/ECD/FPD analysis were investigated for organochlorine (hexachlorobenzene, β-HCH, lindane, δ-HCH, endosulfan ether, heptachlor, aldrin, heptachlor epoxide, α-endosulfan, p, p′-DDE, endrin, β-endosulfan, p, p′-DDD, endosulfan sulphate, p, p′-DDT, methoxychlor) and organophosphorus pesticides (diazinon, parathion methyl, fenitrothion, malathion, fenthion, chlorpyrifos, methidathion) in serum and urine samples. Quantitative application of SPME for the determination of selected pesticides in biological fluids required dilution of samples prior to SPME, in order to reduce matrix influence on the extraction of pesticides, and the use of surrogate standards for accurate quantitation. In this way, quantitation can be carried out by means of external standards prepared in ultra-pure water. Optimised procedures were applied to spiked samples in order to obtain analytical characteristics. Recoveries obtained were generally satisfactory and over 70% in most cases, with relative standard deviations in the range of 1–20% at all concentration levels tested. Limits of detection, calculated as the signal equal to three times background noise using chromatograms of samples spiked at the lowest level, were in the range of 1–10 ng ml −1 for serum samples (δ-HCH, 20 ng ml −1 and methidathion, 15 ng ml −1), and in the range of 0.1–0.4 ng ml −1 for organophosphorus pesticides in urine samples (methidathion, 20 ng ml −1). Finally, developed procedures were applied to real-world samples obtained from exposed and non-exposed subjects, several organochlorine pesticides being detected in some of the samples.