Abstract: Electron probe microanalysis (EPMA) is a method for in-situ analysis of major element contents in minerals. However, it is a challenge to improve precision and accuracy for the analysis of trace elements by EPMA. Changing accelerating voltage, increasing beam current, and increasing counting time are the common methods to improve the precision. However, these methods are easy to destroy the samples and cause element migration, resulting in the inaccuracy of the analytical results. Increasing the counting time will also reduce the analytical efficiency. In this paper, a method of simultaneous determination of an element by multi-spectrometer is proposed to improve the intensity of characteristic X-ray. In this method, multi-spectrometer is used to measure the characteristic X-ray intensity of an element simultaneously. The total characteristic X-ray intensity of standard and unknow are obtained by multi-spectrometer. Then, combined the content of the element in the standard, the content of the element in unknows can be calculated. This method can significantly improve the characteristic

X-ray intensity, leading to high precision and low detection limit. In this study, the contents of Al and Ti in a reference quartz standard were measured by the method of simultaneous determination of an element by multi-spectrometer, to verify the application of this method in trace element analysis. Two wavelength dispersive spectrometer with one TAP crystal and one TAPL crystal were used to measure Al simultaneously, and three wavelength dispersive spectrometer with three PETL crystals were used to measure Ti simultaneously. The multipoint background method, and the condition of 20 kV accelerating voltage, 500 nA beam current, and 20 μm beam diameter were used. The detection limit of Al and Ti in this study were 2.6×10-6(3σ) and 2.1×10-6(3σ), respectively. The analyses result of Al and Ti in this reference standard were
163.8×10-6±5.8×10-6 (3σ) and 56.5×10-6±2.0×10-6 (3σ) respectively, which are all close to the reference values (154×10-6±15×10-6 for Al and 57×10-6±4×10-6 for Ti), and show a good long-term stability.

Key words: EPMA, trace element, multi-spectrometer, simultaneous determination, quartz