Substoichiometric Isotope Dilution Analysis for the Determination of Iron in Biological Materials and Comparison with Substoichiometric Isotope Dilution Mass Spectrometry

Substoichiometric isotope dilution analysis for the determination of trace iron has been studied by using synergistic extraction of iron(III) with a substoichiometric amount of 4-isopropyltropolone (Hipt) in the presence of an excess of 3,5-dichlorophenol (DCP) in heptane. Optimum conditions for the substoichiometric extraction of iron(III) in g to sub-g levels were examined and the high selectivity for iron(III) toward various metal ions encountered in the analysis of biological materials was confirmed. The present method was applied to a biological reference material (NIES, CRM No.9, sargasso) without any pre-separation and was successfully evaluated. Furthermore, substoichiometric stable isotope dilution mass spectrometry using the present extraction method was also used with the above sample. Applicability and practicability was compared for both substoichiometric methods.     

Transformation of microcrystalline state of hydrogenated silicon to amorphous one due to presence of more electronegative impurities

When a slight fraction (～ 2 mol %) of N₂ is added into H₂, sputtering atmosphere for microcrystalline hydrogenated Si films, without changing other fabrication parameters, the amorphous film rather than microcrystalline one forms. The stabilization mechanism of the amorphous film of Si is discussed through TEM and IR observations of this kind of transformation from microcrystal to amorphous state.