Negative thermal ionization mass spectrometry of selenium part 3.* Selenium trace determination in food samples

Abstract

Selenium traces are analysed in different animal tissue samples with isotope dilution mass spectrometry using the formation of negative Se− thermal ions (NTI-IDMS) for isotope ratio measurements. An enriched82Se spike is applied for the isotope dilution technique. After decomposition of the food samples with a HNO3/HCIO4 mixture selenium is separated by the formation of SeH2 using a hydride generation system which is normally applied for atomic absorption spectrometry. Selenium hydride is absorbed in a cone. HNO3 solution, from which sample mass spectrometric determinations are carried out. The recovery of selenium for the total sample treatment has been determined with a75Se tracer to be about 62%. The precision of the IDMS method in the concentration range of 0.1–10 μg/g lies between 1.8% and 4.1 %. The IDMS results agree well with the certified values of the analysed standard reference materials. A comparison of these results with those achieved by an isotope dilution method, using the formation of piazselenol and gas-chromatographic separation (GC-IDMS), and by hydride generation atomic absorption spectrometry (HGAAS) is given. Whereas the NTI-IDMS and GC-IDMS results are in very good agreement, HGAAS can be affected by interferences.