Enhancing the detectability of Ag, Cd, Hg, In, Pb, Tl, and Zn in water by solution anode glow discharge coupled with argon jet cathode and external magnetic field

An atomic emission spectrometry based on solution anode glow discharge coupled with argon jet cathode and magnetic field (SAGD-AJC-MF) was constructed for the detection of trace Ag, Cd, Hg, In, Pb, Tl, and Zn in water samples, where a plasma was produced between a platinum spiral-wrapped ceramic capillary anode and an argon jet titanium (Ti) nozzle cathode, and an external magnetic field was used to enhance excitation efficiency by altering electron trajectories and increasing the collision frequency between electrons and neutral atoms. The results found that the optimal operating parameters are pH = 1.6 HNO₃ as supporting electrolyte, 3.4 mL min⁻¹ solution flow rate, 300 mL min⁻¹ Ar flow rate, and 2.0 mm discharge gap. A 0.55 T external magnetic field reduces the red-hot degree of the cathode Ti nozzle, widen the application range of voltage and reduce the interference. The emission intensities, sensitivities and limit of detection (LOD) were improved by 2.0–3.3, 2.6–4.7 and 2.8–5.2 times, respectively. The SAGD-AJC-MF are employed for the analysis of water samples by standard addition method, the measured results are basically consistent with those obtained by ICP-AES, and the recoveries in spiked Yellow River and wastewater samples are ranged from 89.2 % to 107.8 %, confirming the feasibility, accuracy and reliability. In short, the SAGD-AJC-MF has outstanding performance in water quality monitoring and environmental warning due to a compact, portable and low-cost analytical instrument.