Determination of acetylcholine and choline by flow-injection with immobilized enzymes and fluorometric or luminometric detection.

A method for determination of picomolar quantities of acetylcholine and choline in solutions and tissue extracts is described. The analytes are injected into a continuous stream of a simple medium flowing through a sequence of enzyme reactors containing acetylcholinesterase, choline oxidase, and peroxidase. Additional reactors with choline oxidase and catalase are used to remove endogenous choline from the tissue extracts in which the content of acetylcholine is to be measured. Reaction products are detected fluorometrically or luminometrically. The limits of sensitivity are about 10 pmol/sample with luminometric and 0.2 pmol/sample with fluorometric detection.