SIMULTANEOUS DETERMINATION OF TRACE IMPURITIES IN HIGH-PURITY CHROMIUM METAL AND CHROMIUM DISILICIDE BY INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY AFTER COPRECIPITATION

Although chromium(III) was quantitatively coprecipitated with lanthanum hydroxide, chromate(VI) was not. The different behaviour of chromate(VI) was used for the analysis of chromium metal and chromium disilicide. Chromium (III) was oxidized to dichromate(VI) by fuming with perchloric acid and converted into chromate(VI). The pH was adjusted to 11.0 with sodium hydroxide solution. Ten trace elements (As, Co, Cu, Fe, Mn, Ni, Ti, V, Zn and Zr) in chromium metal and chromium disilicide were quantitatively coprecipitated with lanthanum hydroxide and separated from the chromium matrix. These trace elements were simultaneously determined by inductively coupled plasma atomic emission spectrometry using matrix-matched calibration solutions.