Determination of endocrine disruptors in water after derivatization with N-methyl-N-(tert.-butyldimethyltrifluoroacetamide) using gas chromatography with mass spectrometric detection

The combined gas chromatographic determination of a number of hydroxyl-group containing endocrine disruptors, including 4-octylphenol, 4-nonylphenol, 2,4-dichlorophenol, pentachlorophenol, 4-tert.-butylbenzoic acid, bisphenol-A, 17β-estradiol and 17α-ethynylestradiol, was investigated. Derivatization, required for sensitive determination of these compounds, was carried out using N-methyl-N-(tert.-butyldimethyltrifluoroacetamide). A number of parameters affecting the derivatization reaction, like temperature, time, matrix, solvent, and amount of reagent were studied in detail. Quantitative yields were obtained for real-life extracts after optimization, but the hormones were only mono-substituted. Both solid-phase extraction (SPE) and liquid–liquid extraction were studied as extraction methods, with emphasis on SPE material and effect of pH. Recoveries and RSD for analysis of surface water samples were 58–106 and 6–16% (n=4), respectively, when using SPE, and 109–117 and 6–14% (n=6) when using liquid–liquid extraction. The method developed allows routine analysis of surface water for traces of endocrine disruptors. The limits of detection of were 4–6 ng/l but higher for the hormones.