DIRECT DETERMINATION OF TRACE-ELEMENTS IN NIOBIUM, TANTALUM AND THEIROXIDES BY INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY AFTER MICROWAVE DISSOLUTION

Analytical schemes for the determination of trace elements in high-pur ity niobium, tantalum and their oxides are proposed. The schemes are b ased on microwave dissolution of the metals and oxides followed by ind uctively coupled plasma atomic emission spectrometry (ICP-AES) determi nation of impurities in the solutions. The possibilities of intereleme nt and off-peak background corrections in ICP-AES analysis are discuss ed. The accuracy of the results obtained is confirmed by the determina tion of trace elements after a matrix sorption separation procedure. F or a number of elements, a comparison of the results obtained by ICP-A ES without and with the matrix separation procedure and by electrother mal atomic absorption spectrometry (ETAAS) shows good agreement. The l imits of detection for direct ICP-AES determination are in the range 0 .4-1.0 mu g g(-1) for Ba, Ca, Fe, Mg, Mn, Y and La; between 2.0 and 10 .0 mu g g(-1) for B, Cd, Co, Cr, Cu, Hf,Mo, Na, Nb, Ni, Pb, Sr, Ti, Zr and Ta; and for K, Sb and W a detection limit of 20 mu g g(-1) is ach ieved. The schemes proposed are intended for rapid routine analysis. ( C) 1997 Elsevier Science B.V.