ELECTROTHERMAL VAPORIZATION INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY FOR DETERMINATION OF METAL IMPURITIES IN SLURRIES OF ALUMINUM-OXIDE

A new analytical procedure for the direct determination of metal impur ities in aluminium oxide by ultrasonic slurry sampling-electrothermal vaporization-inductively coupled plasma mass spectrometry (ETV-ICP-MS) is reported. The elements studied include Cr, Cu, Ga, Fe, Mg, Mn, Na, V and Zn, Two samples of fine alumina powder (including the certified reference material NIST SRM 699) were used in this study without any additional pre-treatment. Analytical results of the external calibrati on using aqueous standards, the external calibration using matched mat rix standards and the standard additions method are presented and comp ared, The most appropriate (average accuracy of 97 +/- 5.5% for sample NIST SRM 699) was the standard additions procedure of calibration. An acceptable agreement was found between the results of the slurry samp ling procedure and the certified or reference values, and the repeatab ility of measurements was always better than 13.6%. Some other analyti cal figures-of-merit, e.g., limits of detection, are also presented. T he absolute limits of detection (for the analysis of 15 mu l samples) ranged from 0.8 to 8.3 pg. The speed and multi-element analytical pote ntial of this technique seem to be very advantageous.