Sensitivity improvement of solution cathode glow discharge-atomic emission spectrometry by using refrigerating anodes for optical determination of metal elements

In this study, a refrigerating anode method was developed to improve solution cathode glow discharge-atomic emission spectrometry (SCGD-AES) for the determination of elements. Spectral characteristics of metal anodes at different temperatures were studied in the range from 10 to 30 degrees C. The spectral signals of metals were enhanced by reducing the metal anode temperature during the plasma discharge. Moreover, the method of the refrigerating anode improved the stability of spectral emission of metal elements. Compared with the unrefrigerated system under the same experimental conditions, the detection limits of Ag, Cd, Cu, Mn and Zn were 0.6, 9.1, 5.3, 8.7 and 16 mu g L-1, respectively, which represented the improvements by 6.5, 3.5, 3.2, 3.9 and 3.1 times, respectively. The measurement results of Ag, Cd, Cu, Mn and Zn in a certified reference solution (BWB2446-2016) and an actual water sample from the Yangtze river by SCGD-AES with the refrigerating anode were in agreement with the reference values measured by ICP-OES. The water sample recovery from the Yangtze river ranged from 101.5 to 110.0%, suggesting that the measurement results exhibited high accuracy and reliability. All the results indicated that SCGD-AES coupled with a refrigerating anode could improve its analytical ability and provide an analytical method for in situ, real-time and on-line determination of metal elements in water samples.