Application of atmospheric pressure glow discharge generated in contact with liquids for determination of chloride and bromide in water and juice samples by optical emission spectrometry

Novel atmospheric pressure glow discharge (APGD) microplasma systems, sustained between a miniaturized flowing anode (FLA) or cathode (FLC) and a He jet, were investigated for the direct determination of Br and Cl, using optical emission spectrometry (OES). The impact of the most crucial operating parameters, i.e., the acid type and its concentration, the discharge current, the gas flow rate, and the sample flow rate, was studied for each of the proposed APGD-based systems. Under the optimized conditions, the analytical figures of merit were determined. The susceptibility to the matrix effects of both developed methods was verified as well. It was found that the mechanism of the analytes transport into the discharge likely relied on the cathode sputtering in the case of FLC-APGD and the formation of the volatile Br and Cl species for FLA-APGD. The DLs of Br and Cl were established to be relatively high, i.e., 0.15 and 1.5 mg L-1 for FLA-APGD and 2.1 and 18 mg L-1 for FLC-APGD. However, both studied methods turned out to be resistant to the presence of foreign ions in a sample, at relatively high concentrations. Hence, the proposed methods could be successfully applied for the determination of Br and Cl in water and juices samples and no major differences between the results obtained using the external standard calibration and the standard addition method were found.