RESUMEN
A tyrosinase-based amperometric biosensor is proposed for determination of bisphenol A (BPA) in a flow-batch monosegmented sequential injection system. The enzyme was entrapped in a sol-gel TiO2 matrix modified with multi-walled carbon nanotubes (MWCNTs), polycationic polymer poly(diallyldimethylammonium chloride), (PDDA) and Nafion. Morphology of TYR/TiO2/MWCNTs/PDDA/Nafion matrix composite was studied via scanning electron microscopy (SEM). Electrochemical behavior of the developed biosensor towards bisphenol A was examined and analytical characteristics were assessed with respect to linear range, biosensor sensitivity, limit of detection, long term stability, repeatability and reproducibility. Linear range of biosensor response was found between 0.28 and 45.05 µM with high sensitivity of 3263 µA mM(-1) cm(-2) and detection limit 0.066 µM. The approach was successfully employed for determination of BPA in natural samples.