AMPEROMETRIC FLOW-INJECTION DETERMINATION OF PUTRESCINE AND PUTRESCINE OXIDASE

Flow injection methods for sensitive, accurate and rapid determination of diamines, mainly putrescine (PUT) and cadaverine (CAD), and diamin e oxidase (DAO) are described. Putrescine determination is based on an immobilized enzyme reactor (IER) loaded with putrescine oxidase and a mperometric detection of the produced hydrogen peroxide at a platinum electrode. Putrescine oxidase (PUO) was assayed by simple injection of putrescine oxidase solution into a carrier buffer containing a fixed concentration of putrescine followed by similar detection of hydrogen peroxide. In PUT measurements peak currents were linearly related to p utrescine concentration in the range from 10 mu M to 1 mM with sample frequency of similar to 70 samples/hour. No change in sensitivity and detection limit were observed after more than 1000 injections over a t wo week period. PUO was determined in the range of 50-2500 mU/ml, with sample frequency of similar to 40 samples/hour. The lower detection l imit of the present method (1.5 mU/ml) is suitable for determining the expected low levels of PUO in the amniotic fluid as a possible marker for premature rupture of membranes (PROM). The effects of Bow rates, sample sizes, and substrate concentrations in the detection limits and assay efficiencies are given in the present work. (C) 1998 Elsevier S cience B.V.