EVALUATION OF UNCERTAINTY IN MEASUREMENT FOR THE LEAD IN FLOUR BY GFAAS

[Objective] To evaluate the uncertainty in measurement for the lead in flour by graphite furnace atomic absorption spectrometry,according to JJF 1135-2005 Evaluation of Uncertainty in Chemical Analysis Measurement.[Methods] The main sources of the combined uncertainty were considered,such as the uncertainty of weight,uncertainty of volume,standard solution uncertainty,standard curve uncertainty,uncertainty induced by repeatability of measurements.The components of uncertainty and the combined uncertainty were calculated.[Results] The concentration of the lead in flour was 0.122mg /kg,the expanded uncertainty was 0.020mg /kg,and the result of the measurement was(0.122 ± 0.020) mg /kg.[Conclusion] It is very important to correctly choose pretreatment methods and grasp these methods.The uncertainty induced when weighting is small,and it has a little influence on the results.