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Analysis of electronic specialty gases by enclosed inductively coupled plasma atomic emission spectrometry
Two versions of an enclosed inductively coupled plasma source for atomic emission spectrometry have been developed for the direct analysis of specialty gases: a low-flow enclosed ICP (EICP) discharge sustained inside a spherical quartz container, and an extended, closed-torch ICP (ECT-ICP) based on a conventional ICP torch. The former is optimized for halogens and hydrogen halogenides, and the latter is designed for volatile inorganic hydrides, phosphine in particular. Both techniques offer rapid multielement analysis, wide linear dynamic range, direct sample introduction, minimal sample consumption, and instant atomization of both particulate and gaseous impurities. All parts of the arrangements on are leak-proof and corrosion resistant to ensure safe handling of toxic, corrosive, or otherwise reactive samples and to minimize sample contamination. ^ Four complementary calibration approaches have been studied: gas standard dilution, vapor phase introduction, and exponential dilution, Arsine, silane, and hydrogen sulfide diluted with argon were used as gas standards for As, Si, and S calibration. Volatile compounds (e.g., trimethylaluminum, carbon tetrachloride, iron pentacarbonyl, diethylzinc, trimethylchlorosilane, triethylgermanium chloride, tetramethyltin, tetraethyllead) were introduced into an exponential dilution flask flushed with argon for Al, C, Fe, Pb, Si, Sn, and Zn calibration. Different organometallic compounds can be employed in the exponential dilution technique; however, some of them partially decompose or adsorb to the surfaces before reaching the EICP discharge owing to their reactivity. ^ Indirect semiquantitative calibration based on the ratios of spectral line intensities measured in the EICP and a conventional ICP has been evaluated. The electron and excitation temperatures in both sources were determined and maintained in a certain fashion, so that atomic line intensities in both were correlated. ^ Three chlorine samples were analyzed using an EICP discharge in 100% chlorine. Detection limits ranged from low ppb (Al, As, Fe, Ge, Pb, Sn, Si, Zn) to sub-ppm (C, S) levels. Phosphine samples were diluted 10-fold with argon for the analysis by ECT-ICP, and the detection limits in phosphine were approximately 10 times higher than in chlorine. Hydrogen bromide was analyzed qualitatively. ^
George G Glavin,
"Analysis of electronic specialty gases by enclosed inductively coupled plasma atomic emission spectrometry"
(January 1, 2000).
Doctoral Dissertations Available from Proquest.