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[目的]评估焦磷酸法测定工作场所空气中矽尘游离二氧化硅含量的不确定度。[方法]依据GBZ/T192.4—2007《工作场所空气中粉尘测定第四部分:游离二氧化硅含量》焦磷酸法,对某工作场所空气中矽尘游离二氧化硅含量测定,并进行不确定度来源及量化分析,最终计算合成不确定度。[结果]经焦磷酸法测定,采集的矽尘样品中游离二氧化硅含量为58.9%,扩展不确定度为2.9%(k=2)。矽尘中有机物均匀性和消解后处理过程引起的不确定度以及重复性测量引起的不确定度,对工作场所空气中矽尘游离二氧化硅焦磷酸法测定结果的不确定度贡献较大,其相对不确定度分别为:urel(org)=1.61×10-3、urel(x)=1.76×10-2和urel(w’)=1.77×10-2。[结论]此方法适用于工作场所空气中矽尘游离二氧化硅焦磷酸法测定结果的不确定度评定,并能确定测定结果误差的主要来源。
[Objective] To evaluate the uncertainty of pyrophosphoric acid determination of silica free silica in workplace air. [Method] According to GBZ / T192.4-2007 “workplace airborne dust determination Part 4: free silica content” Pyrophosphoric acid method, to measure the free silica content in the air of a workplace and to carry out The source of certainty and quantitative analysis, the final calculation of synthetic uncertainty. [Result] The content of free silica in the sample of silica dust was 58.9% and the uncertainty of expansion was 2.9% (k = 2) by pyrophosphoric acid method. Uncertainty caused by the uniformity of organic matter in silica dust and post-treatment of digestion as well as the uncertainty caused by repeatability measurement contribute more to the uncertainty of the determination result of the free silica pyrophosphoric acid in workplace air, The relative uncertainties are: urel (org) = 1.61 × 10-3, urel (x) = 1.76 × 10-2 and urel (w ’) = 1.77 × 10-2. [Conclusion] This method is suitable for evaluating the uncertainty of the determination result of silica dust free silica pyrophosphoric acid in the air of the workplace and can determine the main source of the error of the determination result.