Impedance and voltammetric detection of bromate in food samples using CoPcMWCNTs nanocomposites modified glassy carbon electrode

Highlights

• A sensitive and selective bromate sensor.
• Impedance and voltammetric detection of bromate in food samples via CoPcMWCNTs-GCE.
• CoPcMWCNTs-GCE - a promising electrochemical bromate sensor for food safety assessment.

Abstract

Bromate in food and water has been linked to cancer risks for lifetime exposures, and the present techniques for its detection have significant limitations that necessitate the development of new and more efficient approaches. The study describes the synthesis and characterization of CoPcMWCNTs nanocomposites before modifying a glassy carbon electrode for bromate detection. The nanocomposite CoPcMWCNTs was prepared from cobalt nanoparticles, phthalocyanine, and functionalized MWCNTs via ultrasonication. The successful synthesis of the nanomaterials was confirmed via XRD, UV–visible spectroscopy, SEM, and TEM. The CV and EIS studies in 5 mM [Fe(CN)₆]⁴⁻/[Fe(CN)₆]³⁻ prepared in 0.1 M PBS (pH 7) revealed that the GCE-CoPcMWCNTs exhibited higher current response and faster electron transfer than the other electrodes. The electrochemical reduction of bromate was achieved in a solution containing 0.1 M H₂SO₄ at a pH of 1 using the techniques of electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). Using the SWV technique, an LoD of 1.31 μM was obtained with a sensitivity of 497.59 μA μM⁻¹ over a linear dynamic range (LDR) of 6–20 μM. In contrast, utilizing the EIS technique yielded a lower limit of detection (LoD) of 0.32 μM, accompanied by a sensitivity of 72.42 μM kΩ⁻¹, over a linear dynamic range (LDR) of 1–8 μM. The developed sensor exhibited good selectivity, high stability (93.5 %), and good reproducibility (% RSD; 3.9 %). The proposed sensor successfully detected bromate in bread samples, exhibiting a reasonable recovery rate. Thus, demonstrating the practical application of the sensor to detect bromate in real samples (bread).