[Research on Test Method of Metallic Element Contained in Tea Based on EDXRF Technique].

ABSTRACT

As it has been certified by experimental testing that when using the energy-dispersive X-ray fluorescence (EDXRF) method to analyze the metallic elements contained in the tea the energy segment of effective X-ray fluorescence photons is located between 3 and 16 keV. Accordingly the spectral correction element is targeted at the copper elements located near the energy center(8 keV). The copper elements are also used as the picketage to be the standard curve. In the energy segment of effective X-ray fluorescence photons contained in the tea 1.25 mg · kg(-1) of the average detection limit was obtained by using the spiked method to analyze four elements of copper, iron, zinc and lead. Compared with the flame atomic absorption spectrum(FAAS), the actual relative error of the tested value by EDXRF is less than 6%, and the relative standard deviation is less than 5%. The result by T test shows that p > 0.05. The conclusions are that there are no statistically significant differences between EDXRF and FAAS. The measured results gained by the two methods agree with each other. And EDXRF can be used thoroughly to test the metal contents contained in the tea. The result shows that it is feasible to test the metallic contents contained in the tea by EDXRF, and its measured result can meet the requirements of field testing and analysis.