Trace element analysis of silicon nitride powders by direct solid sampling graphite furnace atomic absorption spectrometry

Abstract

A graphite furnace atomic absorption spectrometry method using direct solid sampling has been developed for the determination of Cr, Cu, Fe, K, Mn, Sb and Zn in powdered silicon nitride. Although during the atomization of all analytes excluding Zn, conversion of silicon nitride into silicon and silicon carbide was taking place and its essential part vaporized in the form of different species, no problems occurred with background correction. Calibration could be carried out by using calibration curves obtained with aqueous standard solutions. In the determination of Fe, before sampling, the platform bottom was covered with graphite powder in order to achieve quantitative vaporization and to increase the lifetime of the platform. For the latter reason, the use of graphite powder was advantageous in the determination of Cr and Cu, too. With sample masses up to about 2 mg applied per analysis cycle, the relative standard deviations were between 5 and 18% (n = 5). For the most sensitive conditions, limits of detection between 0.1 (Zn) and 2 ng g⁻¹ (Fe) are achievable. The accuracy was checked by comparison of the results with those of four other methods including neutron activation analysis whereby good to reasonable agreement was achieved.