Highly sensitive determination of Cd, Co, Hg, Ni, Pb, Tl, Zn by solution cathode glow discharge-optical emission...

Solution cathode glow discharge-optical emission spectroscopy (SCGD-OES) is an emerging analytical technique for trace element detection. By eliminating the need for nebulizers, vacuum pumps, and auxiliary gas supplies, it presents significant potential for the development of portable analytical instruments. However, enhancing the detection sensitivity and anti-interference capability remains essential to meet broader application requirements. Utilizing higher-energy plasma is a viable approach to improve elemental emission responses and mitigate matrix effects, such as the application of a higher current, thereby advancing the technique's practical utility.

This study introduces a pulsed-like SCGD system integrated with OES, where a tungsten anode undergoes periodic vertical movement along the y-axis to enhance the detection of Cd, Co, Hg, Ni, Pb, Tl, and Zn. The emission intensities of these elements synchronize with the anode's motion, reaching their maximum when the anode is closest to the solution cathode within the studied inter-electrode gap. Under optimized conditions, emission intensities were enhanced by factors ranging from 3.5 to 7.2, and signal-to-background ratios improved by factors of 2.4-7.5. The limits of detection for Cd, Co, Hg, Ni, Pb, Tl, and Zn were 4, 17, 31, 19, 21, 2, and 6 μg L^-1, respectively. Furthermore, the system exhibited strong tolerance to coexisting ions, maintaining performance at concentrations up to 300 mg L^-1, and in certain cases up to 500 mg L^-1.

A novel pulsed-like SCGD-OES system has been developed, which enhances detection sensitivity and interference resistance through periodic anode movement. This setup offers a compact, cost-effective, and highly sensitive platform with strong matrix tolerance, demonstrating significant potential for use in portable instruments designed for on-site heavy metal analysis in environmental samples.