THE ANALYSIS OF NONCONDUCTING MATERIALS BY LOW-PRESSURE DISCHARGES - SEDIMENTS AND DRY RESIDUES

The suitability of glow discharges for the analysis of major, minor an d trace elements in a variety of matrices is well corroborated by expe rience accrued to date. To further elucidate the potential of these so urces, the hollow cathode discharge (HCD) was tested in two applicatio n areas not yet fully developed. In the first instance, an investigati on was carried out to assess the capability of this source for charact erizing and assaying electrically non-conducting powders. Both the' co nventional HCD and a version boosted through superposition of a microw ave field at 2450 MHz were used to examine the mineral composition and morphological features of coastal marine sediments previously process ed for preparation of a new multielemental reference material. Assumpt ions on the ablation mechanism were also formulated. In the second cas e, several analytes (Al, As, P, Pb, S, Sb, Si, Sn and Ti) were quantif ied in aqueous solutions after drying. The boosted source was found to considerably enhance the spectral emission compared to that of a conv entional source, as demonstrated by burn-off curves and calibration gr aphs. Both examples testify to the wide range of possibilities offered by this type of discharge.