Evaluation on the Uncertainty of Benzene Measured by Two-stage Thermal Desorption-Gas Chromatography

Objectives To evaluate the uncertainty of benzene determined by two-stage thermal desorption-gas chromatography.

Methods Identifying the source of uncertainty, expressing the combined standard uncertainty and expended uncertainty by calculating the component of uncertainty.

Results The expended uncertainty was 9. 4% when the confidence level was 95% and the coverage factor was 2.

Conclusions The largest contributions of components were the preparation of standard solution and the procedure of standard curve fitting. These components could be cut down by using standard product and apparatus with low uncertainty, adding the dots and measuring times of standard curve fitting, and enhance the ability of personnel in experimentation. Thereby the value of expended uncertainty would be decreased.