5:15 PM - 6:30 PM
[HTT16-P15] Trace element quantification in organic materials by low temperature plasma ashing
Keywords:plasma ashing, isotopic analysis, organic material
Inorganic chemical analysis of various environmental samples has been applied to clarify the elemental cycle on the earth's surface, and determination of elemental concentrations among biological samples and fossil fuels is sometimes necessary for the purpose. Instrumental analyses by Atomic absorption spectrometry, ICP optical emission spectrometry, and ICP mass spectrometry are frequently used for the determination, and decomposition of samples is usually required prior to the analysis. For the decomposition and removal of organic hydrocarbons, which are the main components of organic samples, pretreatment methods using the high-temperature ashing method and the microwave thermal decomposition method have been conventionally used. In the former method, the loss of volatile elements due to high temperature and contamination from the surrounding environments are concerned. In the latter case, there are potential spectral and non-spectral interferences due to a large amount of dissolved organic components remaining in the solution. In particular, a large amount of organic sample must be pretreated for the isotope analysis of trace inorganic elements, so the limitation of the decomposable sample amount is a fundamental problem in the latter method.
Our group has been working on the establishment of a low-temperature plasma ashing method using oxygen radicals as the pretreatment method to efficiently remove organic hydrocarbons in organic samples. Organic hydrocarbons are gradually oxidized in oxygen plasma generated by glow discharge under reduced pressure, and finally removing them into the gas phase. In this report, elemental recovery yields in the low-temperature ashing treatment were evaluated using a commercially available organometallic standard solution. As a result, the yield changed depending on factors such as volatility of element oxides, formation of insoluble compounds during ashing, and solubility of residual ash in various inorganic acids. This method was applied to crude oil, seaweed, and brown rice, and their elemental yields were evaluated.
Our group has been working on the establishment of a low-temperature plasma ashing method using oxygen radicals as the pretreatment method to efficiently remove organic hydrocarbons in organic samples. Organic hydrocarbons are gradually oxidized in oxygen plasma generated by glow discharge under reduced pressure, and finally removing them into the gas phase. In this report, elemental recovery yields in the low-temperature ashing treatment were evaluated using a commercially available organometallic standard solution. As a result, the yield changed depending on factors such as volatility of element oxides, formation of insoluble compounds during ashing, and solubility of residual ash in various inorganic acids. This method was applied to crude oil, seaweed, and brown rice, and their elemental yields were evaluated.