Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.
(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)
Sealed inductively coupled plasma analytical atomic emission spectroscopy
Abstract
Conventional inductively coupled plasma-atomic emission spectroscopy (ICP-AES) has disadvantages which can limit its usefulness in situations for which sample is restricted, materials are hazardous, or detection limits are insufficient. Large volumes of argon (10 to 15 L min$\sp{-1}$) flowing at high velocities (10 m s$\sp{-1}$) result in analyte dilution and short analyte residence times. Some of the limitations of conventional ICP-AES may be overcome by forming a non-flowing or low-flow discharge inside a quartz container. To detect metals, modifier gases such as hydrogen and hydrogen chloride must be included in the argon gas stream feeding the sealed ICP. Experimental variables for a sealed ICP system are investigated and optimized for emission spectroscopic determination of arsenic and phosphorus. Important parameters include: generator power, modifier content, discharge container geometry, operating pressure, and operating procedure. Less important are total gas flow rate, container preparation and construction, and induction coil geometry. The optimum geometry is a 40-mm sphere with an induction coil approximately 5-mm larger in diameter. A generator power of 950 W and a hydrogen content of 4% result in detection limits for arsenic and phosphorus that are in the low parts-per-billion range, comparable to those obtained with other analysis techniques. A hypothesis explaining observations of analyte emission transients is developed to provide direction for subsequent container designs. Proof of this hypothesis will require techniques to probe surface species and species distribution within the sealed ICP container. A potential application of the sealed ICP is the analysis of permanent and reactive gases. This potential is demonstrated by the quantitative and qualitative analysis of silane, a pyrophoric gas used to fabricate semiconductor devices. A six-fold excess of hydrogen chloride is required to prevent deposition of silicon oligomers. Al, As, C, Cu, Fe, Ge, Mg, Na, Sn, Ti, and Zr are detected in silane-containing mixtures. Fe, Ge, Mg, Sn, Ti, and Zr are identified in the silane. Changes in the emission spectrum when silane is added to the discharge indicate that silane alters the processes occurring in the plasma, affecting the emission of other elements.
Subject Area
Analytical chemistry
Recommended Citation
Jahl, Matthias J, "Sealed inductively coupled plasma analytical atomic emission spectroscopy" (1992). Doctoral Dissertations Available from Proquest. AAI9219450.
https://scholarworks.umass.edu/dissertations/AAI9219450