Development of micro-enzyme electrode for detection of acetylcholine and choline

Two kinds of simple, micro-enzyme electrodes were devised for a more highly sensitive detection of acetylcholine and choline. The first electrode was made by directly cross-linking acetylcholinesterase (AChE) and choline oxidase (ChO) using glutaraldehyde vapor on a micro platinum disk (diameter 200μm). The second electrode was made by cross-linking with glutaraldehyde vapor after adsorbing AChE and ChO into platinum black particles. By micro flow injection analysis the amperometric performance of the first electrode was found to be better than that of the second one. The detection limit was 20fmol for acetylcholine and 10fmol for choline in the first electrode. The first electrode was successfully utilized as the amperometric detector for micro high performance liquid chromatography.