This work reports monoamine oxidase (MAO)/horseradish peroxidase (HRP) and diamine oxidase (DAO)/horseradish peroxidase (HRP) based biosensors using screen-printed carbon electrodes for the determination of biogenic amines (BA). The enzymes have been covalently immobilized onto the carbon working electrode, previously modified by an aryl diazonium salt, using hydroxysuccinimide and carbodiimide. The detection has been performed by measuring the cathodic current due to the reduction of the mediator hydroxymethylferrocene at a low potential, 250 mV vs screen-printed Ag/AgCl reference electrode. The experimental conditions for the enzymes immobilization, as well as for the main variables that can influence the chronoamperometric current have been optimized by the experimental design methodology. Under these optimum conditions, the disposable biosensors have been characterized. A linear response range from 0.2 up to 1.6 microM and from 0.4 to 2.4 microM of histamine was obtained for DAO/HRP and MAO/HRP based biosensors, respectively. The biosensor construction was highly reproducible, yielding relative standard deviations of 10% and 11% in terms of sensitivity for DAO/HRP and MAO/HRP based biosensors, respectively. The capability of detection, 0.18+/-0.01 microM in the case of DAO/HRP and 0.40+/-0.04 microM (alpha=0.05 and beta=0.005) for MAO/HRP based biosensors, and the biosensor sensitivity towards different BA has also been analyzed. Finally, the developed biosensors have been applied to the determination of the total amine content in fish samples.
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