A miniaturized atmospheric pressure glow microdischarge system generated in contact with a hanging drop electrode – a new approach to spectrochemical analysis of liquid microsamples

Abstract

A newly developed atmospheric pressure glow discharge (APGD) microplasma system generated in contact with a hanging drop electrode (HDE) was investigated here in detail. The proposed system enabled very low consumption of sample solutions (0.4 mL min⁻¹) and power (below 50 W). Additionally, self-ignition of the discharge was observed when sample solutions were introduced into the plasma zone. Under optimized conditions, limits of detection for Ag, Cd and Zn were 2.1, 2.4 and 6.0 μg L⁻¹, respectively, which are comparable with those obtained using a bulky ICP-OES system, while mean repeatability was within 2–5%. Tolerance of the applied microplasma system to the presence of easily ionizable elements (EIEs), i.e., Ca, Mg, Na, and K, was also studied. The effect of addition of organic compounds (methanol, ethanol, and formic and acetic acids) into sample solutions on the analytical performance of the applied microplasma system was examined as well. Accuracy of the proposed method was verified by analysis of a pig kidney (ERM-BB186) certified reference material (CRM). Additionally, tap and spring waters spiked with Ag, Cd and Zn ions were analyzed and recoveries of these analytes were determined.