Ultra-sensitive determination of Zn, Cd, Ni, Cu, and Pb in high salt matrix water samples using solid phase extraction coupled with solution cathode glow discharge atomic emission spectrometry

Herein, we developed a highly sensitive method based on solution cathode glow discharge atomic emission spectrometry (SCGD-AES) coupled with solid-phase extraction (SPE) for the determination of Zn, Cd, Ni, Cu, and Pb in high salt matrix water samples. The trace metals were collected from 100 mL water which was adjusted the pH to 4–10 (this step was unnecessary for most environmental water samples due to their inherent pH compatibility) using a column (i.d. = 6.6 mm) of a chelating resin (bed height = 7.2 cm) and eluted with 5 mL 1 M HNO₃ at a flow rate of 3 mL/min. At the same time, the pH of the eluate would be adjust from 0 to 0.9 (a suitable acidity for SCGD) by the resin column. Then the heavy metals in elute were detected by SCGD with constant current mode. When 100 mL sample water was enriched, the detection limits of Zn, Cd, Ni, Cu, and Pb were 1, 0.6, 2, 0.6, and 6 μg/ L which were improved by almost 20 times. And the tolerance of SCGD for Cd, Cu, Ni, Pb, and Zn detection against the salt matrix (exemplified by Na) could reach up to 10000 mg/L. The method’s accuracy and practicality were validated through successful application to environmental water samples, high salt matrix simulated water and certified reference materials (GBW08608).