On the coupling of hydride generation with atmospheric pressure glow discharge in contact with the flowing liquid cathode for the determination of arsenic, antimony and selenium with optical emission spectrometry

The miniaturized atmospheric pressure glow discharge (APGD) sustained between a liquid flowing cathode and a He nozzle jet anode was combined with hydride generation (HG) to improve the performance of the determination of As, Sb and Se with optical emission spectrometry (OES). As(III), Sb (III) and Se(IV) species were converted into volatile hydrides in the reaction with NaBH4 and right after that they were delivered to the near-anode region of APGD through the nozzle. The transport efficiency of As, Sb and Se to the discharge was several times higher, while intensities of atomic emission lines of As, Sb and Se were improved 3 orders of magnitude (as compared to intensities acquired for the near-cathode region in a APGD system with a typical introduction of analytes through sputtering of the flowing liquid cathode). The effect of the concentration of NaBH4 and HCl in a sample solution, the discharge current, the flow rate of He carrier/jet-supporting and He shielding gases on the emission yield coming from As, Sb, Se, He and H atomic lines and OH and N-2 band heads as well as the electron number density was thoroughly studied. Under compromised conditions, limits of detection (3 sigma criterion) of As, Sb and Se were respectively 4.2, 1.2 and 3.1 mu g L-1. Usefulness of the method was confirmed by the analysis of Sniadecki and Marchlewski highly mineralized spring waters (Kudowa Zdroj, Poland) on the content of As, Sb and Se. Recoveries of elements added to these spring waters were within 90.3-103.7% proving good accuracy of the HG-APGD-OES method. (C) 2015 Elsevier B.V. All rights reserved.