Doctoral Dissertations

Date of Award

8-1996

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

Michael J. Sepaniak

Committee Members

Joseph R. Peterson

Abstract

The research presented in this dissertation concerns the analysis of certain environmentally important metals and compounds. In the analysis of lanthanum and lanthanide metals (referred to herein as "lanthanide metals"), the mobility of the background ion used in the indirect absorbance detection was determined to be very important. The best background ion found was 2-ethylimidazole. The sample matrix and method of injection also had an enormous effect on the analytical figures of merit. Hydrostatic injections from water produced the best LODs (ranging from about 1.7 to 5.4 ppm for the metals studied) and efficiency but had high asymmetry and coefficients of variation. Hydrostatic injections from running buffer exhibited good reproducibility but poor LODs. This method of lanthanide determination has limited applicability due to the necessity of stacking to achieve moderate LODS.

The analysis of the uranyl cation in groundwater developed herein exhibits high selectivity and good LODs (25 ppb) although a system peak is produced which could not be resolved from the analyte peak. Capillary length and diameter affected detectability and the resolution between the system and analyte peaks. This method is applicable to realistic samples and is a sensitive, rapid, inexpensive screening tool for the detection of the uranyl cation. some impurities. The method developed herein lacked the necessary precision for the determination of the two major components. However, the LODs seen in the analysis of the impurities (from 2.5 to 14 ppb) were good. When a real liquid propellant sample was analyzed, the hydroxylamine peak obscured the possible ethanolamine and ammonia peaks; when diethanolamine was spiked into the sample at a concentration of 30 ppb, the signal was easily detected. Diethanolammonium nitrate can be present as an impurity in the triethanolammonium nitrate used in the formulation of the liquid propellant and this method is shown to be a speedy, inexpensive and sensitive determination.

Note: The term "rare earth metals" is used in the title due to paperwork requirements for graduation. The term "lanthanide metals" is used throughout the dissertation to refer to lanthanum and the lanthanide series.

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