Date of Award

1986

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry & Biochemistry

Program/Concentration

Chemistry

Committee Director

Patricia A. Pleban

Committee Member

John D. Van Norman

Committee Member

Frank E. Scully, Jr.

Committee Member

Kenneth G. Brown

Call Number for Print

Special Collections LD4331.C45S28

Abstract

Nickel has been widely used as a matrix modifier in the flameless atomic absorption analysis of arsenic and selenium. Its utility as a modifier for tin has been investigated using Polarized Zeeman effect Graphite Furnace Atomic Absorption Spectroscopy. Peak area, peak shape, and appearance times were compared in modified and nonmodified standards using the system computer's internal integration and a detector/readout system with 18 msec resolution.

The addition of nickel at 600 mg/L increased the tin absorbance signal five-fold. The improved signal to noise ratio resulted in a two-fold increase in the sensitivity and a lower limit of detection. The appearance time of the signal, defined as generation of ten percent of the peak height, was delayed by 30 percent, and the peaks were more symmetric. The appearance temperature of the nickel modified signal was 700 K higher than when no nickel was present. The precision of the analysis, both within a run and between runs, is improved by the addition of nickel. A mechanism to account for the altered atomization profile is proposed using the aid of Arrhenius plots.

The effect of the modifier in the presence of interfering salts was examined. Sodium and potassium sulfates exhibited severe depression of the tin signal when present at low ppm concentrations, an effect which was eliminated by the addition of nickel at 600 mg/L. Ferric chloride exhibited a progressive enhancement of the signal, an effect also eliminated by the addition of nickel. Aluminum nitrate and aluminum chloride each exhibited a more erratic and less reproducible enhancement which was reduced but not eliminated by the addition of nickel. Sulfuric acid had a mild depressive effect on the signal which was unaffected by the presence of nickel. The relative standard deviations of the measurements in these matrices was improved at virtually every level tested.

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DOI

10.25777/991w-2069

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