Objective To optimize N, O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization-gas chromatography for rapid determination of four kinds of chlorophenols.
Methods Mixtures of solvents (hexamethylene:ethyl acetate) at different ratios were compared for the extraction effects of four chlorophenols (2-chlorophenol, 2, 4-dichlorophenol, 2, 4, 6-trichlorophenol, and pentachlorophenol) and one internal standard (2, 4-dibromophenol). The best conditions of BSTFA derivatization were confirmed by orthogonal experiment, including derivation medium, derivatization reagent dosage, derivative temperature, and derivative time. Then gas chromatography with electron capture detector and internal standard was applied to rapidly determine four kinds of chlorophenols in water to verify the applicability of the established method.
Results Using hexamethylene:ethyl acetate (v/v, 4:1) as extraction solvent showed the best extraction effect. According to the results of orthogonal experiment, the best derivative conditions for the selected four chlorophenols included using cyclohexane:acetic ether (4:1) as derivation medium, BSTFA derivatization reagent volume at 140 μL, derivative temperature at 80℃, and derivative time for 30 min. The methodology validation results showed that the linear relationships of the four chlorophenols were good with R2> 0.997 in corresponding concentration ranges, the detection limits were from 0.01 μg/L (2, 4, 6-trichlorophenol) to 0.8 μg/L (2-chlorophenol), and the quantitative limits were from 0.05 μg/L (2, 4, 6-trichlorophenol) to 3.0 μg/L (2-chlorophenol). The addition standard recoveries were in the range of 85.2%-101.2%, and the relative standard deviations were between 0.65% and 3.21% (n=5). After applying to 100 drinking water samples, the relative standard deviations for the optimized method versus national standard testing method were 1.4%-3.7%.
Conclusion The optimized method is advantaged in simple operation, accurate quantification, and nontoxic derivatization reagent; therefore, it is suitable for rapid detection for water samples.
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