Glucose determination in blood samples using flow injection analysis and an amperometric biosensor based on glucose oxidase immobilized on hexacyanoferrate modified nickel electrode

A very simple amperometric enzyme-based glucose sensor is applied as detector in flow injection analysis (FIA) of diabetic patients blood glucose. The enzyme glucose oxidase (GOD) is immobilized by a glutaraldehyde/bovine serum albumin crosslinking procedure on the surface of an alkali nickel hexacyanoferrate thin film electrocrystallized on the nickel electrode. An alkali nickel hexacyanoferrate modified nickel electrode catalyzes the reduction of the hydrogen peroxide, formed by selective biocatalytic GOD action on glucose oxidation by oxygen present in sample solutions. The developed glucose sensor has shown good sensitivity at low negative operating potentials (-300 to -100 mV vs. Ag/AgCl), sufficiently wide linear glucose concentration range (5 mu M-2.9 mM), relatively long operating time (during three months of operation the initial sensitivity decreased only 30%) and no influence of the most common interferences present in human blood like proteins, ascorbic and uric acids.