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 g lassy carbon electrode in terms of the eletrocatalytic effect of Cobalt Hex acyanoferrate (CoHCF) towards thiolcompounds (glutathione (GSH), cysteine ( Cys), N-acetylcysteine (NAC)). Polynuclear CoHCF thin films an electrodepos ited 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 K3Fe(CN)6 and 1 mmol/l CoCl2 in 0.1 mol/l KH2PO4 (pH = 3.0). Combined with liquid chromatography, the CoHCF CME exhibits a good linear relationship be tween the concentration and the current responses of GSH (5.0 x 10(-6)-1.0 x 10(-4) mol/l), Cys (1.5 x 10(-6)-2.0 x 10(-4) mol/l), and NAC (3.0 x 10(- 6)-1.0 x 10(-4) mol/l). The detection limits were 2.5 x 10(-6) mol/l for GS H, 1.0 x 10(-6) mol/l for Cys and 1.5 x 10(-6) mol/l for NAC. We coupled th e microdialysis sampling technique with liquid chromatography-electrochemic al detection (LC-ECD) and successfully determined glutathione in the brain of a freely moving rat. (C) 1999 Elsevier Science B.V. All rights reserved.