Electrochemical sensing platform based on Zeolite/Graphite/Dimethylglyoxime nanocomposite for highly selective and ultrasensitive determination of nickel

In this work, the fabrication and analytical application of a novel, unique, mercury-free, and user-friendly vol-tammetric sensor of Ni(II) based on glassy carbon electrode (GCE) modified with zeolite(MOR)/graphite(G)/ dimethylglyoxime(DMG) composite (MOR/G/DMG-GCE) and the voltammetric procedure for highly selective, ultra-trace determination of nickel ions were reported for the first time. Deposition of a thin layer of the chemically active MOR/G/DMG nanocomposite enables the selective and effective accumulation of Ni(II) ions in the form of the DMG-Ni(II) complex. In 0.1 mol L-1 ammonia buffer (pH 9.0), the MOR/G/DMG-GCE exhibited linear response in the Ni(II) ions concentration range of 0.86 -19.61 mu g L-1 and 0.57 -15.75 mu g L-1, for the accumulation time of 30 s and 60 s, respectively. For 60 s of accumulation time, the limit of detection (S/N = 3) was 0.18 mu g L-1 (3.04 nM), and sensitivity of 0.202 mu A L mu g- 1 was achieved. The developed protocol was validated by the analysis of wastewater certified reference materials. Its practical usefulness was confirmed by the determination of nickel released from metallic jewelry submerged in artificial sweat and stainless steel pot during water boiling. The obtained results were verified by electrothermal atomic absorption spectroscopy as a reference method.

Automated summary

A novel, unique, mercury-free, and user-friendly voltammetric sensor of Ni(II) based on glassy carbon electrode modified with zeolite(MOR)/graphite(G)/dimethylglyoxime(DMG) composite (MOR/G/DMG-GCE) was fabricated and applied for highly selective, ultra-trace determination of nickel ions. The chemically active MOR/G/DMG nanocomposite enabled the selective and effective accumulation of Ni(II) ions as the DMG-Ni(II) complex. The developed protocol showed linear response in the concentration range of 0.86-19.61 μg L-1 and 0.57-15.75 μg L-1 for accumulation times of 30 s and 60 s, respectively, with a limit of detection of 0.18 μg L-1 (3.04 nM) and sensitivity of 0.202 μA L μg-1.