Simultaneous Determination of Choline and Acetylcholine Based on a Trienzyme Chemiluminometric Biosensor in a Single Line Flow Injection System

A detector for the simultaneous determination of choline (Ch) and acetylcholine (ACh) based on a sensitive trienzyme chemiluminometric biosensor in a single line flow injection (FI) system is described. Immobilized choline oxidase (ChOx), immobilized peroxidase (POx), immobilized acetylcholinesterase, and coimmobilized ChOx/POx were packed, in turn, in a transparent ETFE tube (1 mm i.d., 75 cm) and the tube was placed in front of a photomultipier tube as a flow cell. Two-peak response was obtained by one injection of the sample solution. The first and second peaks were dependent on the concentrations of Ch and ACh, respectively. The influence of some experimental parameters such as flow rate, amounts of immobilized enzymes on the behavior of the sensor was studied in order to optimize the sensitivity, sample throughput and resolution. Calibration curves were linear at 1 − 1000 nM for Ch and 3 − 3000 nM for ACh. The sample throughput was 25/h without carryover. The FI system was applied to the simultaneous determination of Ch and ACh in rabbit brain tissue homogenates.