Electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry for the direct determination of trace amounts of impurities in slurries of silicon carbide

Fluorination-assisted electrothermal vaporization (Em)-inductively coupled plasma-atomic emission spectrometry (ICP-AES) for the direct determination of trace amounts of refractory impurity elements in silicon carbide ceramic powders using slurry sampling has been developed. Investigation indicated that a polytetrafluoroethylene (PTFE) emulsion is a useful fluorinating reagent for the destruction of silicon carbide and simultaneous vaporization of the refractory impurities like B, Mo. Ti, and Zr. The vaporization behaviors of the analytes in slurry and solution were comparatively investigated in the presence of PTFE. The fluorinating vaporization processes and the influence factors for this method have been also studied in detail. The experimental results indicated that 80 mug silicon carbide (10 mul of 0.8% (m/v) slurry) could be destroyed and vaporized completely with 600 mug of PTFE under the selected conditions. Calibration was performed using the standard addition method with aqueous standard solutions. The accuracy was checked by comparison of the results with those obtained by solution fluorination-assisted ETV-ICP-AES and pneumatic nebulization (PN)-ICP-AES involving a wet-chemical decomposition of the sample. Detection limits between 0.5 mug g(-1) (8) and 0.2 mug g(-1) (Mo) were achieved. In most cases, the precision expressed as relative standard deviation (R.S.D.) was better than 8%. (C) 2001 Elsevier Science B.V. All rights reserved.