Determination of Heavy Metal Ions in Infant Milk Powder Using a Nanoporous Carbon Modified Disposable Sensor

Highly Dense TiO2 Nanorods as Potential Electrode Material for Electrochemical Detection of Multiple Heavy Metal Ions in Aqueous Medium

This study describes the direct deposition of extremely dense TiO2 nanorods (NRs) on an ITO substrate for the improved detection of heavy metal ions (HMIs). A facile hydrothermal method was employed to synthesize TiO2 NRs on the ITO substrate at ~130 °C. Synthesized TiO2 NRs were analyzed for morphological, structural, and electrochemical properties. As an electrode material, TiO2 NRs were used for the simultaneous detection of three HMIs (i.e., Cr3+, Cu2+, and Hg2+), which showed a remarkably high sensitivity of ~92.2 µA.mM-1.cm-2 for the Cu2+ ion. Relatively low sensitivities of ~15.6 µA.mM-1.cm-2 and ~19.67 µA.mM-1.cm-2 were recorded for the Cr3+ and Hg2+ ions, respectively. The fabricated TiO2 NR-based HMI sensor showed an effective dynamic linear detection range with low LOD values of ~21.7 mM, 37 mM, and ~ 28.5 mM for Cr3+, Cu2+, and Hg2+, respectively. The TiO2 NR-based HMI sensor exhibited efficient charge transfer over the electrode toward the trace detection of Cr3+, Cu2+, and Hg2+. Moreover, the reliability of the TiO2 NR-based HMI sensor was assessed, which exhibited a promising stability of 30 days. The obtained results indicate that TiO2 NRs grown on an ITO substrate are a promising electrode material for detecting hazardous Cr3+, Cu2+, and Hg2+ and might eventually be commercialized in the near future.

A novel electrode for simultaneous detection of multiple heavy metal ions without pre-enrichment in food samples

Integrating a pre-enrichment step into electrochemical detection methodologies has traditionally been employed to enhance the performance of heavy metal detection. However, this augmentation also introduces a degree of intricacy into the sensing process and increases energy consumption. In this work, Mo-doped WO3 is grown in situ on carbon cloth by one-step electrodeposition. The electrode detect multiple heavy metal ions simultaneously in the range of 0.1-100.0 μM with LODs ranging from 11.2 to 17.1 nM. The electrode successfully detected heavy metal ions in diverse food samples. This pioneering detection strategy realized the direct and simultaneous detection of multiple heavy metal ions by utilizing the valence property of WO3 and oxygen vacancies generated by molybdenum doping. The Mo-WO3/CC pre-enrichment-free detection electrode boasts straightforward preparation, a streamlined detection procedure, swift response kinetics, and superior performance relative to previously reported electrodes, which makes it possible to develop a portable heavy metal ion detection device.