Simultaneously determination of multi metal elements in water samples by liquid cathode glow discharge-atomic emission spectrometry

In this work, a liquid cathode glow discharge-atomic emission spectrometry (LCGD-AES) was constructed for simultaneously determination of K, Na, Ca, Mg and Zn in water samples (tap water, mineral water, Yellow River water and waste water), in which the glow discharge plasma was produced between the needle-like Pt anode and electrolyte around a quartz capillary cathode. The effects of the supporting electrolyte, discharge voltage and organic additives on emission intensity were investigated in detail. The limits of detections (LODs) of metals were compared with those measured by the closed-type electrolyte-cathode discharge-atomic emission spectrometry (ELCAD-AES). In addition, the measured results of water samples using LCGD-were verified by ICP. The results showed that the optimal operation conditions are pH = 1 HNO3 as supporting electrolyte, addition of 0.15% formic acid and 650 V discharge voltage. The R-2 and the RSD are ranged from 0.9887 to 0.9990 and 1.10% to 2.19%, respectively. LODs of K, Na, Ca, Mg and Zn are 0.02, 0.04, 0.19, 0.04 and 0.05 mg L-1, which are in agreement with the ELCAD-AES, and satisfied the recommended levels of the China standards for drinking water quality. The obtained results of Na, K, Ca, Mg and Zn in water samples by LCGD and ICP have certain difference. This result provides an alternative analytical method for the determination of metal elements in water samples. (C) 2016 Elsevier B.V. All rights reserved.