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A voltammetric biosensor based on tyrosinase (TYR) was developed for determination of tyramine. Carbon material (multi-walled carbon nanotubes or mesoporous carbon CMK-3-type), polycationic polymer—i.e., poly(diallyldimethylammonium chloride) (PDDA), and Nafion were incorporated into titania dioxide sol (TiO2) to create an immobilization matrix. The features of the formed matrix were studied by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The analytical performance of the developed biosensor was evaluated with respect to linear range, sensitivity, limit of detection, long-term stability, repeatability, and reproducibility. The biosensor exhibited electrocatalytic activity toward tyramine oxidation within a linear range from 6 to 130 μM, high sensitivity of 486 μA mM−1 cm−2, and limit of detection of 1.5 μM. The apparent Michaelis–Menten constant was calculated to be 66.0 μM indicating a high biological affinity of the developed biosensor for tyramine. Furthermore, its usefulness in determination of tyramine in food product samples was also verified.Graphical abstractDifferent food samples were analyzed to determine tyramine using biosensor based on tyrosinaseElectronic supplementary materialThe online version of this article (doi:10.1007/s00216-016-9612-y) contains supplementary material, which is available to authorized users.

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In this work, a novel voltammetric sensor was developed to determine amoxicillin (AMX). The electrode modification layer consisted of titanium dioxide sol (TiO2) modified with gold nanoparticles (AuNPs), CMK‐3‐type mesoporous carbon and Nafion. The morphology of the electrode composite was studied by scanning electron microscopy (SEM). Electrochemical behaviour of AMX at proposed electrode was studied. Effects of parameters comprising the amount of CMK‐3 and AuNPs in matrix composite, pH of supporting electrolyte and incubation time on the sensitivity of developed sensor were examined. The analytical characteristics of the proposed sensor were assessed. The developed sensor exhibited linear response in two AMX concentration ranges: from 0.5 to 2.5 μM and from 2.5 to 133.0 μM, with sensitivity of 1420 μA mM−1 (5071 μA mM−1 cm−2) and 832 μA mM−1 (2971 μA mM−1 cm−2), respectively. The detection limit was evaluated as 0.3 μM. For verification purposes the sensor was successfully employed in determination of AMX in pharmaceutical product, mineral and environmental water using a flow‐batch monosegmented sequential injection approach.

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