Determination of bismuth in steels and cast irons by atomic-absorption spectrophotometry with an induction furnace: direct analysis of solid samples

Abstract

A graphite induction furnace has been constructed within a Perkin-Elmer 300S atomic-absorption spectrophotometer for the determination of bismuth in 2–12-mg samples of steels and irons that are dropped into the furnace. Calibration graphs of peak absorbance versus mass of bismuth are best constructed by use of standard alloys of roughly similar composition to the samples being analysed but, in the absence of suitable standard alloys, semiquantitative results can be obtained if calibration graphs are prepared using small volumes of a standard bismuth nitrate solution. Samples of alloys can be added to the furnace at 2–5-min intervals. Information is presented on the calibration graphs and on the accuracy, precision and limits of detection of the method for 40 high-purity irons and steels and for nine cast irons. With steels containing more than 0.04 µg g^–1 of bismuth, relative standard deviations of 3–10% are usually achieved. The limit of detection for bismuth in steels is 0.004 µg g^–1 when using this method.