A new potentiometric sensor based on a high-performance composite for nanomolar determination of mercury (II) in environmental samples

Abstract

A new potentiometric sensor for the rapid determination of Hg²⁺ based on modified carbon paste electrode consisting of room temperature ionic liquid, 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF₆), multi-walled carbon nanotubes (MWCNTs), alumina nanoparticles and a synthetic macrocyclic diamide ‘7,10,13-triaza-1-thia-4,16-dioxa-6,14-dioxo-2,3;17,18-dinaphtho-cyclooctadecane’ as an efficient ionophore was constructed. Prepared composite is an ideal paste because it has low drift of potential, high selectivity and fast response time (10 s), which leads to a more stable potential signal. The morphology and properties of electrodes surface were characterised by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy. A linear dynamic range of 2.01–2.01 × 10⁷ µg L⁻¹ with detection limit of 1.40 µg L⁻¹ Hg²⁺ was obtained at pH range of 2.5 to 4.5. The prepared modified electrode shows several advantages such as simple preparation method, high stability of the composite paste, high sensitivity, long-term life time (at least 13 weeks) and remarkable potentiometric reproducibility. The modified electrode was successfully applied for the accurate determination of trace amounts of Hg ²⁺ in environmental samples.

Keywords:

• alumina nanoparticles
• carbon paste electrode
• ionic liquids
• mercury
• potentiometric sensor
• multi-walled carbon nanotubes

Acknowledgements

The authors thank the staff of the organic laboratory for guidance about the preparation of the TDN. The authors wish to thank from Dr Ali Shirzadmehr for valuable discussions and his suggestions.

Supplementary material

Supplementary Table S1 is available online.