SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

A54
SOLID PHASE MICROEXTRACTION GAS CHROMATOGRAPHIC ANALYSIS OF
ORGANOPHOSPHORUS PESTICIDES IN BIOLOGICAL SAMPLES
Nikolaos Raikos*·a, lfigeneia Grigoratou b , Georgios Theodoridis b , Heleni Tsoukali a ,
Dimitrios Psaroulis'
aLaboratory of Toxicology and Forensic Medicine, Medical School; bLaboratory ofAnalytical Chemistry,
Department of Chemistry, Aristotle University, 541 24, Thessaloniki, Greece
A headspace solid phase microextraction (HS-SPME) method in combination with GC-NPD was
developed for the determination of a mixture of organophosphorus pesticides (malathion, parathion,
methyl parathion and diazinon) in biological samples. Fenithothrion was selected as the internal standard.
A 85 !-lm polyacrylate (PA) SPME fiber was selected for sampling. Various extraction parameters were
studied and optimized: salt addition, desorption time, extraction time, extraction temperature. Best
conditions found were: 0.8 g NaCI added in 3 ml aqueous sample, 20 min sampling at 70 ec, 3 min
desorption at 230°C, The HS-SPME method in combination with GC-NPD provided satisfactory detection
sensitivity and liner dynamic range. The method was applied in the determination of the pesticides in
various biological specimens: human whole blood, plasma, liver, kidney and cerebrospinal fluid. The
inherent selectivity provided by the NPD detector together with the efficient sample clean-up of the HS­
SPME resulted in clear chromatograms with no interferences. Extraction recovery varied significantly from
specimen to specimen. Linear response data for these OPPs was obtained with correlation coefficients
ranging between 0.9866 and 0.9999. High GC signals were observed for diazinon, as a result low limits of
detection were observed. Limits of detection (LODs) were in the range of 2-10 nglg for diazinon. In
contrast the signals obtained for methyl parathion and malathion were significantly lower, thus higher
limits of detection were observed. Estimated LODs ranged from 35 to 55 ng/g for methyl parathion. The
proposed methodology renders an efficient, cost effective and simple and sample preparation process for
the determination of OPPs. Most important, the technique overcomes limitations and obstacles of
conventional methods such as the use of expensive and toxic organic solvents and the application of tedious
and cumbersome procedures.
Keywords: Organophosphorus pesticides, HS-SPME, Biological samples
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