Objective To identify the best experimental condition for simultaneous determination of four chlorophenols in drinking water by single-drop microextraction (SDME) and gas chromatography-mass spectrometry (GC-MS).
Methods The method involved addition of 2, 4-dibromophenol as internal standard into 50 mL water samples, followed by extraction and derivatization at different conditions, and quantification using GC-MS detection. The best conditions for SDME efficiency was applied to analyze four chlorophenols in drinking water. The results determined by this method were compared with those by the national standard method.
Results The optimized conditions for SDME were summarized as follows: hexane-toluene (1:1) as solvent; N-methyl-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTF) as derivatization reagent; 20% MTBSTFA; microextraction was performed in a medium of 200 g/L NaCl, with a stirring rate of 200 r/min for 30 min. Calibration curves for the four chlorophenols (2-chlorophenols, 2, 4-dichlorophenols, 2, 4, 6-trichlorophenols, and pentachlorophenols) were linear within the range of 0.2-100.0 μg/L. The correlation coefficients were 0.999 3, 0.999 3, 0.998 7, and 0.999 9, respectively. The limits of detection were 0.021, 0.018, 0.026, and 0.035 μg/L, respectively. The average recoveries ranged from 85.6% to 104.0% at three spiked levels of 1, 10, and 80 μg/L for each chlorophenol, and the relative standard deviations ranged from 2.5% to 9.4%. No significant difference was found in the results between the proposed method and the national standard method.
Conclusion The proposed method is simple, rapid, highly consistent with the standard method, and thus suitable for the determination of chlorophenols in drinking water.
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