Direct atomic spectrometric analysis of aluminium oxide by continuous powder introduction into microwave induced plasma

Abstract

A direct solid sampling microwave induced plasma atomic emission spectrometric procedure for trace impurities determination in metal oxide samples has been developed. Test samples (0.5–1 g) were ground and placed in the sample chamber of a continuous powder introduction (CPI) system, which was directly connected to the MIP. Powder samples were carried in an argon stream as a dry aerosol. The atomic vapor generated in the plasma produced a stable signal, allowing scanning of emission spectra in selected wavelength ranges. The effects of operating conditions and sample particle size on the analytical signal were evaluated. Calibration for Cu, Mg, Si and Zn was performed using different metal oxide samples (Al₂O₃, MgO, SnO₂, La₂O₃) of spectrographic grade for element content up to about 10 μg g⁻¹. The detection limit values for some elements obtained with the CPI-MIP-AES method were in the range of 45–220 ng g⁻¹. The proposed method was validated by analyzing the SRM 699 Alumina (reduction grade) certified reference material using both calibration with solid standards and standard addition technique with solution standards. The results obtained were typically within the 95% confidence interval of the certified or information value.