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

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 1.2V and -0.2V versus Ag/AgCl in a fresh modification solution containing 0.5mmol/l K₃Fe(CN)6 and 1mmol/l CoCl₂ in 0.1mol/l KH₂PO₄ (pH=3.0). Combined with liquid chromatography, the CoHCF CME exhibits a good linear relationship between the concentration and the current responses of GSH (5.0x10^-6-1.0x10^-4mol/l), Cys (1.5x10^-6-2.0x10^-4mol/l), and NAC (3.0x10^-6-1.0x10^-4mol/l). The detection limits were 2.5x10^-6mol/l for GSH, 1.0x10^-6mol/l for Cys and 1.5x10^-6mol/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. Copyright (C) 1999 Elsevier Science B.V.