Original Development of a Molecularly Imprinted Electrochemical Sensor for Selective Detection of Ochratoxin A in Groundnut Products from Nigerian Markets

Ochratoxin A is a potent nephrotoxic and nephrocarcinogenic mycotoxin produced by Aspergillus and Penicillium species that contaminate staple crops including groundnuts, which are widely consumed across Nigeria. Rapid, low-cost detection methods that can be deployed at market level are urgently needed to protect public health, yet conventional laboratory methods are too expensive and equipment-intensive for routine market surveillance across Nigeria's vast geography. This study developed an original molecularly imprinted polymer-based electrochemical sensor for rapid, selective, and sensitive detection of ochratoxin A in groundnut products from Nigerian markets. The molecular imprinting was performed using acrylamide as functional monomer, ethylene glycol dimethacrylate as crosslinker, and ochratoxin A as template on a screen-printed carbon electrode modified with gold nanoparticles and multi-walled carbon nanotubes. Sensor fabrication, template removal, and rebinding conditions were systematically optimised. The recognition mechanism was characterised by electrochemical impedance spectroscopy and cyclic voltammetry. Selectivity was evaluated against ochratoxin B, aflatoxin B1, deoxynivalenol, and zearalenone. Analytical performance was validated against high-performance liquid chromatography with fluorescence detection. The sensor exhibited a linear response range of 0.01 to 100 nanograms per millilitre with a detection limit of 0.004 nanograms per millilitre, substantially below the EU regulatory limit. High selectivity against structurally similar mycotoxins was confirmed by imprinting factor analysis. Application to 50 groundnut market samples from Kano and Kaduna States demonstrated 94.7 percent agreement with HPLC reference values. This original sensing system provides a deployable, affordable alternative to laboratory-based mycotoxin monitoring for Nigerian food safety authorities.

Keywords: molecularly imprinted polymer, electrochemical sensor, ochratoxin A, mycotoxin detection, groundnut contamination