Study of a direct current atmospheric pressure glow discharge in helium with wet aerosol sample introduction systems

• Published in: Journal of analytical atomic spectrometry 2014-04, Vol.29 (4), p.674-68
• Main Authors: Moß, Katharina Karoline, Reinsberg, Klaus-Georg, Broekaert, José Alfons Clement
• Format: Article
• Language: English
• Subjects: Aerosols; Atmospheric pressure; Copper; Direct current; Discharge; Drying; Glow discharges; Spectroscopy
• ISSN: 0267-9477; 1364-5544
• DOI: 10.1039/c3ja50190f

In this study a He DC atmospheric pressure glow discharge (APGD) is characterized under dry conditions and with the introduction of wet aerosols. The aerosols are generated by a conventional pneumatic nebulization system using a MicroMist nebulizer placed in a double pass spray chamber according to Scott or alternatively by a custom-built drop-on-demand (DOD) system based on printer cartridges. The experiments are performed at a He gas flow of 500 mL min −1 and 40 mA current. The influences of the H 2 O load on the discharge rotational temperature ( T rot ), excitation temperature ( T exc ) and the electron number density ( n e ) are determined. Temperature reductions when comparing dry and wet conditions are found to be around 500 K for the T rot and 240-400 K for the T exc . Detection limits for the elements Cd, Cu, Mg, Mn and Na are presented for pneumatic nebulization coupled to a continuous flow injection system. They are found to be between 10 μg L −1 for Na and 140 μg L −1 for Cu. In the case of the drop-on-demand system a value of 16 μg L −1 for Na was obtained. The applicability of the discharge to the determination of Na in a tap water sample at concentration levels of 20 mg L −1 is shown for both introduction systems and the accuracy of the results is found to be within 1.3 mg L −1 as compared to the result of inductively coupled plasma optical emission spectrometry (ICP-OES). A small scale He-atmospheric pressure glow discharge was characterized and applied for elemental determinations, with solutions using a pneumatic nebulizer and a drop-on-demand nebulization system.