Journal of Chromatography & Separation Techniques
Open Access
ISSN: 2157-7064
+44 1300 500008
ISSN: 2157-7064
+44 1300 500008
Valentin A Krylov and A J Sozin
N I Lobachevskii Nizhny Novgorod State University, Russia
Posters & Accepted Abstracts: J Chromatogr Sep Tech
At present time, there is a great interest to simple substances, including isotopically enriched ones, with the ultimately low content of impurities. A suitable method for production and ultra purification of the initial substances is their use in the form of volatile hydrides. Gas chromatography-mass spectrometry is the most promising method of analysis of highpurity substances which make it possible to reliably detect the impurities with high sensitivity. It is for the first time that the method of gas chromatography-mass spectrometry was used to determine the impurity composition monoisotopic silanes 28SiH4, 29SiH4, 30SiH4 and germanes 72GeH4, 74GeH4, 76GeÐ4. Introducing of gaseous samples into gas chromatograph was carried out by automatic two-position valve â??Valco EH2C6WEZPH-CER5â?, connected with the developed sampling vacuum system. 56 impurity components have been determined including the permanent gases, arsine, phosphine, the homologs of silane, disiloxane, sulfur hexafluoride, carbon bisulfide, hydrocarbons, chloro- and fluoroorganic substances. The positive chemical ionization method was used to identify impurities missing in the individual state and thus, not included in the library of mass spectra. It is the first found that monoisotopic hydrides contain an increased concentration of substances that have displaced isotopic composition. The quantitative analysis has been conducted by the method of absolute calibration. The determination of substances missing in the individual state was based upon the dependence of analysis sensitivity on their ionization cross section. The limits of detection for impurities are 2x10-6 â?? 1x10-9 mol. %, which are by 8-20 times lower than those given in literature.
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