Amperometric flow-injection method for determination of biogenic diamines and hypoxanthine by combined use of immobilized enzyme reactors and a peroxidase electrode

Abstract

A flow-injection system is proposed for the determination of meat freshness, based on the simultaneous determination of polyamines and hypoxanthine. A putrescine oxidase reactor and xanthine oxidase reactor were incorporated at fixed positions in a flow system, which was based on the splitting of the flow after sample injection and subsequent confluence before reaching the peroxidase electrode. Because each channel has a different residence time, two peaks were obtained. The first peak corresponded to the total polyamine concentration (putrescine, cadaverine and spermidine) the second peak to hypoxanthine. The calibration graphs were linear in the range 1 × 10 −6–5 × 10 −4 M. The detection limit was 0.5 × 10 −6 M for polyamines and hypoxanthine. The measurement of polyamines and hypoxanthine contents in porcine loin meat could be performed at a rate of 25 samples per hour with satisfactory precision (<1.5% R.S.D.).