Determination of Trace Quantities of Chromium and Manganese in Steel, Ore, and Liquid Samples by Atomic Absorption Spectrometry Atomic absorption spectrometry (AAS) is a powerful and versatile technique for the determination of trace metals, and all chemistry students should he introduced t o it. There are several excellent analytical chemistry texts which introduce the student to the theory behind AAS, hut unfortunately few of these texts give experiments which demonstrate the practical use of this technique. In order to demonstrate the use of AAS to the students we developed a praetical determination of chromium and manganese in steel, ore, and liquid samples. The procedure consists of five steps: (1) preparation and standardization of manganese and chromium solutions (the chromium solutions contained sodium sulfate as a masking agent'); (2) digestion of the weighed solid samples or dilution of the liquid samples; (3) preparation of the Perkin-Elmer Model 303 atomic absorption spectmphotometer; (4) procurement of the absorption data; and ( 5 ) preparation of the calibration curves and calculation of the results. The calibration curves and the results were obtained with the aid of a Hewlett-Packard Model 9830 programmable calculator whieh was equipped with a plotter. The student values agreed well with the actual values far a variety of unknowns, and the experiment could he completed in two 3-hr periods. This experiment demonstrates valuable techniques. The students not only learn and experience the operating techniques, but they also experience typical sampling procedures, digestion procedures, and computer operation. Finally, they learn to appreciate the atomic absorption procedure when they compare it to the colorimetric procedure.2 Copies of the procedures and results are available upon request.
J. A,, and Chriswell, C. D., A n d Chem., 43.465 (1911). Skoog, D. H., and West, D. M., "Fundamentals of Analytical Chemistry," 2nd Ed., Holt, Rinehart and Winston, Inc.,New York, 1969, pp. 692-693. 1 Hurlbut,
Metropolitan State College Denver, Colorado 80204
734 / Journal of Chemical Education
Jeffrey A. Hurlbut Lowell K. Gilbert Bruce N. Buddington Terry F. Rees
