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

Evaluation of Uncertainty in Determining Free Silica in Silica Dust in Air of Workplace by Pyrophosphoric Acid Method

[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 free silica in silica dust in the air of workplace by pyrophosphoric acid method. [Methods] Free silica in silica dust was measured by pyrophosphoric acid method according to the Determination of Dust in the Air of Workplace-Part 4： Content of Free Silica in Dust（GBZ/T 192.4-2007）. The uncertainty in the process was sourced, quantified, and systematically calculated. [Results] With 58.9% of free silica in silica dust by pyrophosphoric acid method, the extended uncertainty was 2.9%（k=2）. Post-treatment of digestion [urel（x）=1.76×10-2], uniformity of organic materials [urel（org）=1.61×10-3], and repeated measurements [urel（w＇）=1.77×10-2] were the key factors influencing the reliability of results by pyrophosphoric acid method. [Conclusion] The method is applicable to evaluate the main sources of result error in the uncertainty evaluation of free silica of silica dust in the air of workplace by pyrophosphoric acid method.