Goddard Sharon L, Brown Richard J C
Analytical Science Division, National Physical Laboratory, Teddington, Middlesex TW11 0LW, UK.
Sensors (Basel). 2014 Nov 17;14(11):21676-92. doi: 10.3390/s141121676.
Monitoring stationary source emissions for heavy metals generally requires the use of quartz filters to collect samples because of the high temperature and high moisture sampling environment. The documentary standard method sample preparation technique in Europe, EN 14385, uses digestion in hydrofluoric acid and nitric acid (HF/HNO3) followed by complexing with boric acid (H3BO3) prior to analysis. However, the use of this method presents a number of problems, including significant instrumental drift during analysis caused by the matrix components, often leading to instrument breakdown and downtime for repairs, as well as posing significant health and safety risks. The aim of this work was to develop an alternative sample preparation technique for emissions samples on quartz filters. The alternative techniques considered were: (i) acid digestion in a fluoroboric acid (HBF4) and HNO3 mixture and (ii) acid extraction in an aqua regia (AR) mixture (HCl and HNO3). Assessment of the effectiveness of these options included determination of interferences and signal drift, as well as validating the different methods by measurement of matrix certified reference materials (CRMs), and comparing the results obtained from real test samples and sample blanks to determine limits of detection. The results showed that the HBF4/HNO3 mixture provides the most viable alternative to the documentary standard preparation technique.
由于采样环境温度高且湿度大，监测固定源排放中的重金属通常需要使用石英滤膜来采集样品。欧洲的文件标准方法（EN 14385）中的样品制备技术是在分析前先使用氢氟酸和硝酸（HF/HNO₃）进行消解，然后与硼酸（H₃BO₃）络合。然而，使用这种方法存在许多问题，包括分析过程中基质成分导致的显著仪器漂移，这常常会导致仪器故障和停机维修，同时还存在重大的健康和安全风险。这项工作的目的是为石英滤膜上的排放样品开发一种替代的样品制备技术。考虑的替代技术有：（i）在氟硼酸（HBF₄）和HNO₃混合物中进行酸消解，以及（ii）在王水（AR）混合物（HCl和HNO₃）中进行酸萃取。对这些方法有效性的评估包括干扰和信号漂移的测定，以及通过测量基质有证标准物质（CRM）来验证不同方法，并比较从实际测试样品和样品空白中获得的结果以确定检测限。结果表明，HBF₄/HNO₃混合物是文件标准制备技术最可行的替代方法。
