Determination of trace amounts of reduced glutathione by a chemical oscillating reaction

Abstract

An analytical method for the determination of trace amounts of reduced glutathione (GSH) by its perturbation on the copper(II)-catalysed oscillating reaction between hydrogen peroxide and sodium thiocyanate is proposed. The reaction is implemented in a continuous-flow stirred-tank reactor, and changes in the oscillating period on each perturbation are proportional to the GSH concentration. The use of the analyte pulse perturbation technique permits sequential determinations on the same oscillating system owing to the expeditiousness with which the starting conditions are restored after each perturbation. Two different methodologies were used to address the determination. The dynamic range lies between 0.1 an 0.7 µmol of GSH and the precision is excellent (less than 0.7% as relative standard deviation). Some aspects of the potential mechanism of action of GSH on the oscillating system are discussed.