Immersed solvent microextraction of phenol and chlorophenols from water samples followed by gas chromatography–mass spectrometry

A homemade immersed solvent microextraction (SME) device was successfully developed for the trace enrichment of phenols from aqueous samples. A microdrop of butyl acetate was suspended from the tip of a microsyringe needle, immersed in an aqueous spiked solution for a preset time. The microdrop was then retracted into the microsyringe and injected directly into a gas chromatography–mass spectrometry (GC–MS) injection port. Effects of different parameters such as the type of solvent, extraction time, stirring rate, and temperature were investigated and optimized. To reduce the polarity of phenols and prevent tailing effects, all the phenols were derivatized prior to extraction using acetic anhydride in basic media. The enrichment factor and linearity was studied by preconcentration of 1 ml of HPLC-grade and river water, spiked with a standard solution of phenols at a concentration range of 0.05–50 μg l−1 (R.S.D. < 10%). The correlation coefficient was satisfactory (r2 > 0.98) for all the studied analytes. Detection limits were obtained using HPLC-grade and river water, i.e. 5–22 ng l−1. The proposed method was successfully applied to the extraction and determination of some environmentally important phenols in different water samples.