Spectrofluorimetric study of the complexation of ochratoxin A and Cu2+: Towards the hybrid fluorimetric sensor and visual detection of ochratoxin A in wheat flour samples from farm to fork.

Abstract In this study, the ochratoxin A (OTA) interaction with some metal cations exhibits a quenching effect of the Cu2+, Co2+, and Ni2+ in the OTA intrinsic fluorescence intensity. The property of the OTA fluorescence change in complexation with the Cu2+ has been applied in developing a label-free and selective fluorimetric sensor for fast detection of the OTA trace amounts in wheat flour samples. The achieved color difference map (CDM) based on the spectral profile provides the technical support for the rapid visual sensing of OTA in the wheat flour samples. The feasibility of the hybrid fluorimetric sensor and visual OTA detection in wheat flour samples has been confirmed with the high-performance liquid chromatography (HPLC) method as a standard method. The calculated LOD (0.4 ng g−1) and LOQ (1.2 ng g−1) values of the proposed method are much lower than the maximum permissible limit of OTA value reported by the European Union (5 ng g−1).