FLUORINATION AND VOLATILIZATION OF REFRACTORY ELEMENTS FROM A GRAPHITE-FURNACE FOR SAMPLE INTRODUCTION INTO AN INDUCTIVELY COUPLED PLASMA BY USING A POLYTETRAFLUOROETHYLENE SLURRY

A method was developed to determine refractory elements by inductively coupled plasma atomic emission spectrometry (ICP-AES) with sample introduction by electrothermal vaporization. A slurry of polytetrafluoroethylene was used to form fluorides rather than carbides of the elements. In this way, the refractory elements were efficiently vaporized and subsequently introduced into the plasma. The detection limits for Zr, V, Cr, W, Mo, B and Ti were improved by a factor of 7-119, compared with those of electrothermal vaporization ICP-AES without the fluorinating agent. No memory effects were observed and adequate precision was obtained. The fluorination process is also discussed.