能量色散X射线荧光法测定石油产品中总硫含量不确定度的评定

Evaluation of uncertainty in measurement of total sulfur content in petroleum products by energy dispersion X-ray fluorescence spectrometry

关键词:  能量色散X射线荧光法  总硫含量  不确定度  相对标准不确定度

Key words:  energy dispersive X-ray fluorescence method  total sulfur content  uncertainty  relative standard uncertainty

摘要:

采用能量色散X射线荧光法测定石油产品中总硫的含量,选择在高浓度或低浓度的工作曲线下对样品进行检测,对在测定过程中引入的各项不确定度进行评定,各项不确定度以相对标准不确定度量化表示,通过计算出样品的扩展不确定度,为最终数据的报出提供可靠的保障和参考。通过分析得出,该方法的不确定度主要由拟合曲线、计数率、样品的重复测定、标样总硫含量的误差、仪器的重复性导致的。在取置信度为95%,包含因子k=2,对于总硫质量分数为816 mg/kg的样品,测定结果为(816±25)mg/kg,对于总硫质量分数为2.640%的样品,结果为(2.640±0.092)%。 

Abstract:

The total sulfur content in petroleum products by energy dispersive X-ray fluorescence spectrometry was determined. The sample can be determined by low or high sulfur content, and the uncertainty of total sulfur that be introduced in petroleum product was evaluated. The uncertainties are quantified by relative standard uncertainties, and the extended uncertainty of the standard is obtained by calculation, which can provide reliable guarantee and reference for the report of final data. The analysis result shows that the uncertainty of this method is mainly caused by the fitting curve, the counting rate, the repeated determination of samples, the error of total sulfur content of the standard samples, and the repeatability of the instrument. Under the condition that the confidence probability is 95% and the inclusion factor k=2, for the samples with total sulfur mass fraction less than 1000 mg/kg,and the result is (816±9) mg/kg, and for the samples with the mass fraction between 0.1% and 5.0%, the result is (2.640±0.045)%, both of the extended uncertainty corresponding to both are lower than the requirement of repeatability of the standard, indicating that the data produced by the instrument has good reliability.