Determination of minor and trace elements in ferrochromium and ferromanganese by inductively coupled plasma atomic emission spectrometry

Abstract

A procedure using inductively coupled plasma atomic emission spectrometry (ICP-AES) has been developed for the analysis of ferrochromium and ferromanganese, i.e., for the determination of aluminium, cobalt, chromium, copper, manganese, molybdenum, nickel, silicon, titanium and vanadium. The sample is dissolved with a mixture of phosphoric and sulphuric acids in a polytetrafluoroethylene vessel without the application of hydrofluoric acid. In this way both ferrochromium and ferromanganese samples are quantitatively converted into a soluble form. No separation of the analyte elements from the matrix is required. The sample dissolution procedure, the instrumental conditions for ICP-AES, some important spectral interferences, the precision of determination and detection and determination limits are given. The detection limits were 12 ng ml^–1 for Co, Cu and V; 60 ng ml^–1 for Mn, Mo, Ni, Si and Ti; 120 ng ml^–1 for Al and Cr. The precision of determination characterized by ten standard deviations was 20–40 ng ml^–1 for Co, Cu and V; 200–400 ng ml^–1 for Al, Cr, Mn, Mo, Ni, Si and Ti. The sample dissolution was also performed in a microwave oven. The analytical procedures were verified by means of Czechoslovak, British and German ferrochromium and ferromanganese certified reference materials. The silicon content in the ferroalloys was also verified by a gravimetric method. For comparison, the samples were analysed by flame atomic absorption spectrometry.