Compact glow discharge for the elemental analysis of aqueous samples

Glow discharge sources have shown impressive analytical performance, cost effectiveness, and versatility but have traditionally been ill-suited for the analysis of liquids or solutions. However, in recent years, glow discharges operated at atmospheric pressure have shown progress in this direction. In particular, glow discharges have been operated with the solution to be analyzed acting as one of the electrodes (most typically, and most successfully, the cathode). These sources exhibit many of the traditional advantages of glow discharges (such as low power requirements) and possess the additional benefit of not requiring vacuum equipment. In the present study, a modified design is introduced and its analytical performance is evaluated. The modification from the most similar source is primarily a reduction in discharge volume (nearly 5-fold, to 2 mm(3)) and a corresponding increase in power density. With the new design, detection limits for a range of metals are greatly improved, with most now in the single and sub-part per billion range.