Kunikazu Ide

Determination of traces of selenium in heat-resisting alloys by graphite-furnace atomic-absorption spectrometry after co-precipitation with arsenic

Traces of selenium in complex nickel- and cobalt-based heat-resisting alloys have been determined by co-precipitation and graphite-furnace atomic-absorption spectrometry. The alloys are dissolved in a mixture of concentrated hydrochloric acid, concentrated hydrofluoric acid and 30% hydrogen peroxide. Selenium does not volatilize to any significant extent during the dissolution and concentration. Selenium is separated from the matrices as the element by co-precipitation with arsenic and is redissolved in nitric acid. Zinc is added to the solution to stabilize selenium during the ashing step and thus to enhance the absorbance in the atomization step. Standard solutions for the calibration are prepared in a similar manner to sample solutions after dissolution of the arsenic carrier. The detection limit for selenium is 0.3 ppm in the heat-resisting alloy.