Direct determination of trace copper and chromium in silicon nitride by fluorinating electrothermal vaporization inductively coupled plasma atomic emission spectrometry with the slurry sampling technique

A method has been developed for the determination of trace impurities in si licon nitride (Si3N4) powders by fluorination assisted electrothermal vapor ization (ETV) /ICP-AES using the slurry sampling technique. Polytetrafluoro ethylene (PTFE) emulsion as a fluorinating reagent not only effectively des troys the skeleton of Si3N4, but also carries out selective volatilization between the impurity elements (Cu, Cr) and the matrix (Si). The experimenta l parameters influencing fluorination reactions were optimized. The detecti on limits for Cu and Cr are 1.05 ng/mL( Cu) and 1.58 ng/mL (Cr), the RSDs a re in the range of 1.9-4.2%. The proposed method has been applied to the de termination of Cu and Cr in Si3N4 ceramic powders. The analytical results w ere compared with those obtained by independent methods.