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Analysis of electronic specialty gases by sealed inductively coupled plasma-atomic emission spectrometry (SICP -AES)

Reha Kadir Tepe, University of Massachusetts Amherst

Abstract

The Sealed Inductively Coupled Plasma Atomic Emission Spectrometer (SICP-AES) was developed for toxic and reactive gas analysis. The most important challenge in using this technique routinely to determine the metallic impurities in toxic and reactive gases is calibrating the system for metals such as Fe, Ni, Cr, and Mo. The unavailability of appropriate gaseous standards that contain these metals prevents a straightforward approach toward calibration. ^ Two classes of organometallic Fe and Ni compounds were investigated for calibration. The first consists ferrocene, Fe(C5H5) 2, and nickelocene, Ni(C5H5)2. Corresponding diffusion tubes of these compounds were employed to calibrate for Fe and Ni in chlorine. The detection limits of Fe and Ni were 20 and 9 pg mL −1, respectively. ^ The second class of compounds were carbonyls of Fe and Ni. Fe(CO) 5 and Ni(CO)4 are in gas phase at room temperature. This property allowed one to use them as calibration materials without significant modification to the gas handling system. However, their high toxicity required extreme caution. The detection limit of Fe was 290 pg mL−1. ^ Iron pentacarbonyl proved to be extremely useful in calibrating the system for Fe in presence of Cl2. Unfortunately a Ni carbonyl standard mixture was not commercially available owing to its high toxicity. As a result, the production of these carbonyls as a calibration source was investigated. ^ These carbonyls were synthesized by the reaction between Fe and Ni powders in the presence of carbon monoxide at high pressures and temperatures. The quantification was accomplished by using a number of different chemicals such as nitric acid and dilute iodine solutions. ^ Additionally, the system was calibrated for sulfur in Cl2. Sulfur hexafluoride, SF6, was employed as the calibration material . Since 100% SF6 was used, there was a need to dilute it five orders of magnitude to obtain low ppm concentrations of S. Therefore, a gas handling system was designed that allowed the accurate dilution of SF6. Sulfur detection limit was 195 ppb (v/v). ^ Finally, anhydrous hydrogen bromide was analyzed qualitatively by SICP-AES. All the emission lines of bromine between 200–900 nm were tabulated, the molecular features, and the impurities were identified. ^

Subject Area

Analytical chemistry|Chemical engineering

Recommended Citation

Tepe, Reha Kadir, "Analysis of electronic specialty gases by sealed inductively coupled plasma-atomic emission spectrometry (SICP -AES)" (1999). Doctoral Dissertations Available from Proquest. AAI9920658.
http://scholarworks.umass.edu/dissertations/AAI9920658

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