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 rea gent for the destruction of silicon carbide and simultaneous vaporization o f the refractory impurities like B, Mo. Ti, and Zr. The vaporization behavi ors of the analytes in slurry and solution were comparatively investigated in the presence of PTFE. The fluorinating vaporization processes and the in fluence factors for this method have been also studied in detail. The exper imental 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 u nder the selected conditions. Calibration was performed using the standard addition method with aqueous standard solutions. The accuracy was checked b y comparison of the results with those obtained by solution fluorination-as sisted 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 ex pressed as relative standard deviation (R.S.D.) was better than 8%. (C) 200 1 Elsevier Science B.V. All rights reserved.