Determination of glutathione in vivo by microdialysis using liquid chromatography with a cobalt hexacyanoferrate chemically modified electrode

Abstract

A new chemically modified electrode (CME) was found to be comparable to a glassy carbon electrode in terms of the eletrocatalytic effect of Cobalt Hexacyanoferrate (CoHCF) towards thiolcompounds (glutathione (GSH), cysteine (Cys), N-acetylcysteine (NAC)). Polynuclear CoHCF thin films are electrodeposited on a glassy carbon electrode by potential cycling between 1.2 V and −0.2 V versus Ag/AgCl in a fresh modification solution containing 0.5 mmol/l K 3Fe(CN)6 and 1 mmol/l CoCl 2 in 0.1 mol/l KH 2PO 4 (pH = 3.0). Combined with liquid chromatography, the CoHCF CME exhibits a good linear relationship between the concentration and the current responses of GSH (5.0 × 10 −6–1.0 × 10 −4 mol/l), Cys (1.5 × 10 −6 –2.0 × 10 −4 mol/l), and NAC (3.0 × 10 −6–1.0 × 10 −4 mol/l). The detection limits were 2.5 × 10 −6 mol/l for GSH, 1.0 × 10 −6 mol/l for Cys and 1.5 × 10 −6 mol/l for NAC. We coupled the microdialysis sampling technique with liquid chromatography-electrochemical detection (LC-ECD) and successfully determined glutathione in the brain of a freely moving rat.