The analysis of non-conducting materials by low-pressure discharges: sediments and dry residues

Abstract The suitability of glow discharges for the analysis of major, minor and trace elements in a variety of matrices is well corroborated by experience accrued to date. To further elucidate the potential of these sources, the hollow cathode discharge (HCD) was tested in two application areas not yet fully developed. In the first instance, an investigation was carried out to assess the capability of this source for characterizing and assaying electrically non-conducting powders. Both the conventional HCD and a version boosted through superposition of a microwave field at 2450 MHz were used to examine the mineral composition and morphological features of coastal marine sediments previously processed for preparation of a new multielemental reference material. Assumptions on the ablation mechanism were also formulated. In the second case, several analytes (Al, As, P, Pb, S, Sb, Si, Sn and Ti) were quantified in aqueous solutions after drying. The boosted source was found to considerably enhance the spectral emission compared to that of a conventional source, as demonstrated by burn-off curves and calibration graphs. Both examples testify to the wide range of possibilities offered by this type of discharge.