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Abstract：
Metal occupational exposure limits mainly focus on total content of the respective metals of interest. The methods applied for trace metal analysis in occupational health and safety laboratories are usually standardized to pragmatic consensus digestion schemes, ensuring comparability of results. The objective of the present study entailed the evaluation of a recently developed HNO3-only microwave-assisted digestion procedure by comparison with the German consensus hot-block digestion and other national digestion schemes. An inter-laboratory comparison test with participation of nine national occupational health and safety laboratories from Europe and North America was organized. For adequate emulation of what workers are at risk of inhaling four different industrial metal processing workplace dusts (electronic recycling, high-speed steel grinding, cylinder head cleaning, and battery combustion ash) were homogenized and sieved to the particle size < 100 µm diameter at IFA. The participants were asked to process air sample-typical amounts according to the German hot-plate technique, the IFA microwave-assisted digestion scheme as well as their national or in-house conventional digestion method for airborne dust and analyze for Cd, Co, Cr, Co, Fe, Mg, Ni, Pb, and Zn. Recoveries (relative to consensus open-vessel digestion) obtained for the new IFA microwave-assisted digestion were between 88 and 114% and relative reproducibility standard deviations were <10% for most metals of interest. The in-house digestion procedures applied varied widely but (whether microwave, hot block, or open vessel) yielded comparable results for the predominantly elemental alloy type dusts supplied. Results become more diverse for the combustion dust, especially if a combination of microwave-assisted digestion procedures with high temperatures and hydrofluoric acid is applied. ISO 15202-2 is currently being revised; this digestion procedure will be included as a possible variant in annex 2.
摘要：
金属职业接触限值主要集中在相关金属的总含量。职业健康和安全实验室中用于痕量金属分析的方法通常被标准化为实用的共识消化方案，确保结果的可比性。本研究的目的是通过与德国共识热块消化和其他国家消化方案进行比较，评估最近开发的仅HNO3微波辅助消化程序。组织了来自欧洲和北美的9个国家职业健康和安全实验室参加的实验室间比较测试。为了充分模拟哪些工人有可能吸入四种不同的工业金属加工工作场所粉尘(电子回收，高速钢磨削，气缸盖清洗,和电池燃烧灰）在IFA下均质化并筛分至粒径<100µm直径。参与者被要求根据德国热板技术处理典型数量的空气样品，IFA微波辅助消解方案及其国家或内部常规消解方法，用于空气中的粉尘和Cd分析，Co,Cr,Co,Fe,Mg,Ni,Pb,和Zn。新的IFA微波辅助消解获得的回收率（相对于一致的开放容器消解）在88％至114％之间，大多数感兴趣的金属的相对重现性标准偏差<10％。内部消化程序的应用变化很大，但(无论是微波，热块，或开放式容器）对于提供的主要元素合金型粉尘产生了可比的结果。结果变得更加多样化的燃烧粉尘，特别是如果微波辅助消解程序与高温和氢氟酸的组合应用。ISO15202-2目前正在修订中；此消化程序将作为可能的变体包含在附件2中。
