汽油中微量元素的X射线荧光光谱分析

DETERMINATION OF TRACE ELEMENTS IN GASOLINE BY X-RAY FLUORESCENCE SPECTROMETRY

建立了波长色散X射线荧光光谱仪定量测定汽油中S、P、Mn、Fe和Pb微量元素的方法。采用内标法，分别以Zr、Co、Bi作为S和P、Mn和Fe、Pb的内标，既可校正不同种类汽油基体的差异，也可消除样品杯支撑膜下垂对测定结果的影响。在单元素测定方法的基础上，通过调整上述5种微量元素的测量次序克服了支撑膜吸附被测元素引起的干扰，使本法能够一次性完成上述5元素的测定。实验得到的加有稳定剂的Co内标溶液的稳定时间超过6个月。方法的检出限在0．8～4μg／g之间，相对标准偏差（RSD）均小于1．5％。对比实验结果表明，本方法的结果与湿法化学分析结果相符。

The method for determination of trace elements, namely phosphorus, sulfur, manganese, iron and lead, in gasoline by wavelength dispersive X ray fluorescence spectrometer was developed. By using internal analysis method with zirconium, cobalt, bismuth as the internal standard of phosphorus and sulfur, manganese and iron, lead respectively, the matrix effects of various types of gasoline could be corrected, and the influence of sample support film sagging on the determination could also be eliminated. Based on the single element determination, a simultaneous multi-element determination method was established, by which with an appropriate measurement sequence of the five elements the trouble caused by trace element adsorption on sample support film could be reduced or avoided. The stabilization of cobalt internal solution was studied and one stabilizer solution was found, which could stabilize the cobalt internal solution more than six months. The detection limit （LLD） of this method was between 0.8 and 4 μg/g, and the relative standard deviation （n=7） was less than 1.5%. The results obtained from this method were in satisfactory agreement with those obtained from wet chemical analysis method.