A double-cycle high-speed voltammetric technique allowing direct measurement of irreversibly oxidised species: characterisation and application to the temporal measurement of ascorbate in the rat central nervous system.

The oxidation of ascorbic acid at carbon fibre microelectrodes is irreversible due to rapid hydration of the product. This feature has been employed in the development of a voltammetric assay using a double-cycle voltage sweep. The difference between the current generated on the first and second anodic sweeps is proportional to the concentration of ascorbate. The characterisation and application of the method are discussed.