POLYETHYLENEIMINE-COATED RETICULATED VITREOUS CARBON ELECTRODE WITH IMMOBILIZED ENZYMES AS A SUBSTRATE DETECTOR

Polyethyleneimine (PEI) was covalently coupled to carbodiimide-activat ed reticulated vitreous carbon (RVC). The PEI-coated RVC was activated with glutaraldehyde, and glycerol dehydrogenase and diaphorase were t hen immobilized. The PEI-coated RVC with immobilized enzymes functione d both as an enzyme reactor and a working electrode in an amperometric detection system where NAD(+)/NADH was recycled by the immobilized en zymes. The coated RVC electrode showed good properties compared to unc oated RVC, such as a long Lifetime and a constant response to a series of injections in a flow-injection system, resulting in a relative sta ndard deviation of 1.4%. The calibration graph was linear from the det ection limit 0.1 mu M to 2 mM NADH in the absence of recycling. (C) 19 98 Published by Elsevier Science B.V. All rights reserved.