Investigation of sample decomposition for the trace determination of arsenic, antimony and selenium in organic and inorganic materials using the Wickbold combustion method

Summary

The suitability and efficiency of the Wickbold combustion unit in combination with the new pre-combustion unit VE (manufactured by Fa. Heraeus Quarzglas GmbH) is investigated with respect to its use for the decomposition of samples for the determination of the trace elements arsenic, antimony and selenium. Certified solid reference samples were analyzed for their contents of these elements by decomposition in this apparatus and detection by hydride-AAS. Several additional experimental parameters were investigated in detail. Different absorption solutions were tested as well as the influence of the temperature of the new oven and the influence of the sample size. The new pyrolysis unit is compared with the traditional Wickbold pyrolysis method. Furthermore, the Wickbold method and an aqua regia extraction were compared. The advantages of the Wickbold unit combined with the new combustion unit are shown (especially) for routine analysis of several volatile elements. The versatility of the unit for this group of elements is demonstrated for inorganic as well as organic samples. As there is little need for additional chemicals, this method works with almost no blank value, resulting in very low limits of detection. These are mainly influenced by the method of detection. It is possible to detect 2 μg/L arsenic, 3 μg/L selenium and 5 μg/L antimony without enrichment.