BLOOD COMPATIBILITY AND EXTENDED LINEARITY OF LACTATE ENZYME ELECTRODE USING POLY(VINYL CHLORIDE) OUTER MEMBRANES

A functionally haemocompatible lactate enzyme electrode system with an extended linear range has been developed. The electrode is based on c lassical amperometric detection of hydrogen peroxide produced by the e nzyme lactate oxidase, immobilised in a glutaraldehyde matrix. The sen sor system comprises an outer poly(vinyl chloride), PVC, membrane with incorporated non-ionic surfactant which acts both asa haemocompatible interface and a diffusion barrier, extending the sensor linear range up to at least 90 mM lactate. Electroactive interferents, such as asco rbate, urate and acetaminophen, are effectively excluded by the furthe r use of an inner sulphonated polyether-ether sulphone/polyether sulph one membrane. Membrane composition and fabrication were investigated. The blood compatibility of the outer PVC membranes was evaluated by co mparing sensitivity of the electrode before and after exposure to undi luted whole blood. Scanning electron microscopy (SEM) was also used to examine the membrane surface. Measurements of whole blood and plasma lactate concentrations when compared with those obtained with a standa rd lactate analyser gave, respectively, y=1.2x+050, r(2)=0.97, n=6 and y=0.89x+0.13, r(2)=0.96, n=20. (C) 1997 Elsevier Science B.V.