Evaluation of Uncertainty in the Determination of Trihalomethanes in Drinking Water by Gas Chromatography
Objective:In order to timely and effectively operate GB/T 5750.10-2023,the uncertainty of the determination of five volatile chlorinated disinfection by-products trihalomethanes in drinking water by gas chromatography was evaluated.Method:According to JJF 1059.1-2012,a mathematical model was established to evaluate the uncertainty of five trihalomethanes(chloroform,carbon tetrachloride,dichloro-bromomethane,chlorodibromomethane and tribromomethane)in drinking water by gas chromatography.Result:When the contents of the five trihalomethanes in drinking water were 1.97 μg·L-1,2.01 μg·L-1,1.96 μg·L-1,2.03 μg·L-1 and 1.98 μg·L-1,respectively,the inclusion probability was 95%,and the inclusion factor k=2 had extended uncertainties of 0.21 μg·L-1,0.16 μg·L-1,0.14 μg·L-1,0.16 μg·L-1 and 0.24 μg·L-1,respectively.Conclusion:Through the analysis of uncertainty,it is found that the standard curve fitting residuals are the main source of uncertainty for the determination of five volatile chlorination by-products in drinking water by gas chromatography.Attention should be paid to the operation specification during the experimental operation,so as to increase the number of detections of the standard curve and reduce the uncertainty of curve fitting.
gas chromatographychlorination by-productsdrinking wateruncertainty
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