Amperometric detection of acetylcholine and choline in a liquid chromatographic system with an immobilized enzyme reactor

Acetylcholinesterase and choline oxidase were co-immobilized by reaction with glutaraldehyde onto alkylamino-bonded silica, which was incorporated as the enzyme reactor in an h.p.l.c. system for the determination of acetylcholine and choline. The hydrogen peroxide produced enzymatically in the enzyme reactor, after the separation of acetylcholine and choline by the reverse-phase column, was monitored amperometrically. The detection limits were 1.2 pmol for choline and 1.8 pmol for acetylcholine.