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In this work, a method for the dynamic headspace liquid-phase microextraction/gas chromatography/mass determination of trihalomethanes (THMs) such as chloroform, dichlorobromomethane, chlorodibromomethane and bromoform in drinking water has been described.Three organic solvents-xylene, ethylene glycol and 1-octanol were compared and 1-octanol was the most sensitive solvent for the analytes.Extraction conditions such as headspace volume, solvent volume, extraction times, extraction time period, content of NaC1 and extraction temperature were found to have influence on extraction efficiency.The optimized conditions were 15 ml headspace volume in a 50ml vial, 25 extraction times,26sec extraction time period, 25℃ extraction temperature with 0.25 g/mL NaC1.Based on the optimum conditions the extraction multiple ranged from 31 to 67 for various components.The linear range was 1-100 μg/L for THMs.The limits of detection (LODs) ranged from 0.5μg/L (for dichlorobromomethane, chlorodibromomethane and bromoform) to 0.8μg/L (for chloroform); and relative standard deviations (RSD) for most of THMs at the 10μg/L level were below 8%.Real samples collected from tap water were successfully analyzed using the proposed method.The recovery of real samples was from 95% to 108%.