TRACE CHARACTERIZATION OF HIGH-PURITY MOLYBDENUM AND TUNGSTEN BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY, INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY, INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY AND TOTAL-REFLECTION X-RAY-FLUORESCENCE SPECTROMETRY INVOLVING ANALYTE-MATRIX SEPARATION

A technique for the separation of 42 trace elements from up to 5 g of molybdenum and tungsten matrices was developed by means of the radiotr acer technique. It is based on adsorption of the analyses on the catio n exchanger Dowex 50 W x 9 from a 4% H2O2/0.01 mol l(-1) HNO3 solution followed by their elution with 15 mi of 4 mol l(-1) HNO3 in the oppos ite flow direction. Both matrices were removed with a separation facto r > 10(4). The separation technique was applied to the analysis of the se materials by electrothermal atomic absorption spectrometry, inducti vely coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry and total reflection X-ray fluorescence spetr ometry. For all the determination methods used, the limits of detectio n are given and compared with those of other methods. With inductively coupled plasma mass spectrometry, for 22 of the 30 assayed elements, limits of detection at the sub-ng g(-1) level were achieved. The resul ts are compared with those obtained by radiochemical neutron activatio n analysis in this work and by glow discharge mass spectrometry, secon dary ion mass spectrometry, isotope dilution mass spectrometry and by solution spectrometric methods in other laboratories. (C) 1997 Elsevie r Science B.V.