Determination of phenols in water samples by single-drop microextraction followed by in-syringe derivatization and gas chromatography–mass spectrometric detection

Trace analysis of phenolic compounds in water was performed by coupling single-drop microextraction (SDME) with in-syringe derivatization of the analytes and GC–MS analysis. The analytes were extracted from a 3 ml sample solution using 2.5 μl of hexyl acetate. After extraction, derivatization was carried out in syringe barrel using 0.5 μl of N,O-bis(trimethylsilyl)acetamide. The influence of derivatizing reagent volume, derivatization time and temperature on the yield of the in-syringe silylation was investigated. Derivatization reaction is completed in 5 min at 50 °C. Experimental SDME parameters, such as selection of organic solvent, sample pH, addition of salt, extraction time and temperature of extraction were studied. Analytical parameters, such as enrichment factor, precision, linearity and detection limits were also determined. The limits of detection were in the range of 4–61 ng/l (S/N = 3). The relative standard deviations obtained were between 4.8 and 12% (n = 5).