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A selective and sensitive method has been developed for the determination of clenbuterol in bovine liver samples using differential-pulse voltammetry (DPV), based on the electrochemical behaviour of clenbuterol at a molecularly imprinted polymer (MIP)-modified solid binding matrix composite electrode (SBMCE). The method of clenbuterol detection involves two steps. In the first step, clenbuterol binds selectively to the MIP. In the second step, an electroinactive competitor (isoxsuprine) is added in excess, whence some of the bound clenbuterol is released. The released clenbuterol is analysed using DPV. The electrode renewal was achieved by a simple mechanical polishing step of the SBMCE surface. The determination of clenbuterol in bovine liver fortified with increasing concentrations of this drug is also described, involving liquid–liquid extraction followed by a mixed-mode solid-phase extraction procedure. The integrated MIP–SBMCE displays good mechanical properties, electrochemical performances and can be a very useful tool in monitoring the use of anabolics in meat production.

The present invention describes a new electrochemical biosensor comprising (i) a biocatalyst producing a pH change when interacting with the analyte to be determined and (ii) a compound exhibiting different redox properties both in its protonated and non-protonated forms (pH-sensitive redox compound). The elements described above are integrated in a biosensor system composed of a working electrode and a reference electrode connected to an ammeter. When the analyte is present, the system produces a current change that is proportional to the concentration of the analyte. The biosensors described herein can be used in the accurate detection of a wide range of analytes. They can be used in diagnostics, industrial processes, food and feed quality control, biotechnology, pharmaceutical industry, environmental monitoring and so on.