Abstract

WALISZEWSKI, Stefan M et al. Use of sulfuric acid for organochlorine pesticides determination: I. Analytical quality of fat precipitated by concentrated sulfuric acid in samples with high lipid content. Rev. Int. Contam. Ambient [online]. 2008, vol.24, n.1, pp.33-38. ISSN 0188-4999.

Many papers describe analytical methods for organochlorine pesticide residue determinations in environmental samples. Gas chromatography with electron capture detection requires highly purified extracts, ie. with an efficient clean-up step. To achieve this purpose, different clean-up methods are employed. Most organochlorine pesticides are resistant to sulfuric acid, a property used for the destruction of endogenous compounds and fat precipitation. Both fat extract treatments that use sulfuric acid as a clean-up medium, and quantities of nonvolatile residues determined after the clean-up step, are described. Samples of adipose tissues (human, bovine, pig and chicken), butter and margarine were studied. The analytical method allows good (higher than 90 %) organo-chlorine pesticide recovery and an extract ready for gas chromatography with a minimal amount of nonvolatile compounds (0.8 to 2.2 mg that constitutes 0.22 to 1.87 % of the analyzed sample) determined gravimetrically. The low quantity of nonvolatile residues present in cleaned-up extracts allows multiple sample gas chromatographies without diminishing column resolution and electron capture detector response. The analytical quality study (10 repetitions for each fat sample) shows a 4.8 to 12.5 % coefficient of variation, indicating an appropriate method for fat sample monitoring studies.

Keywords : organochlorine pesticides; fats; sulfuric acid.