Amperometric biosensor for total histamine, putrescine and cadaverine using diamine oxidase

Diamine oxidase was purified from porcine kidney to homogeneity and immobilized onto a porous preactivated nylon membrane. The enzymic membrane was attached to an amperometric electrode for determination of the total concentrations of histamine, cadaverine and putrescine accumulated in fish fillets during storage. For detecting hydrogen peroxide released, the working platinum electrode was poised at +400 mV vs Ag/AgCl to prevent electrode fouling as well as minimize electroactive interferences. The biosensor was linear up to 6 mM with a lower detection limit of 25 mu M for the three substrates and steady state response was achieved within 1.5 min. The enzyme membranes were stable at 5 degrees C for 2 mo and usable for at least 60 assays.