Direct determination of Cu by liquid cathode glow discharge-atomic emission spectrometry

In this study, a novel liquid cathode glow discharge-atomic emission spectrometry was developed for the direct determination of Cu in aqueous solutions, in which the glow discharge plasma was produced in the solution between the needle-like Pt cathode and the electrolyte around it. The effects of discharge voltage, solution pH, and the ionic surfactant cetyltrimethylammonium chloride (CTAC) on emission intensities were investigated. The limit of detection (LOD) of Cu was compared with those measured by closed-type electrolyte cathode discharge-atomic emission spectrometry (ELCAD-AES). The results showed that the optimal operation conditions are voltage of 135V, a pH of 1, and addition of 0.15% CTAC. CTAC can enhance the emission intensity and lower the LOD of Cu I. The net intensity of atomic emission lines of Cu I at 324.8nm with 0.15% CTAC improved by 1.5 fold, and the LODs of the Cu at 135V with 0.15% CTAC and without CTAC are 0.019 and 0.234mgL−1, respectively. The analytical capability of Cu in this study is comparable to the closed-type ELCAD-AES, and it satisfied the recommended levels of Cu in the WHO standards for drinking-water quality. This technique can be effectively used for on-line monitoring of metal ions in aqueous samples. [Display omitted] •LCGD-AES technique is developed.•Analytical performance of LCGD-AES was evaluated by determination of Cu.•Addition of 0.15% CTAC can improve the emission intensity of Cu.•The LOD of Cu in LCGD was found to be comparable to those of similar ELCAD systems.•LCGD can be a promising technique for on-line analysis of metal ions in aqueous samples.