Electrocatalysis and amperometric detection of alditols and sugars at a gold-nickel composite electrode in anion-exchange chromatography

A novel Au-Ni composite electrode prepared by cathodic precipitation/deposition of nickel hydroxide on the gold surface was characterised. The resulting composite electrode was evaluated as an amperometric sensor in flow injection analysis and anion-exchange chromatography for the quantitation of alditols and simple carbohydrates. Constant potential detection at +0.6V vs Ag/AgCl and a pulsed detection mode were employed, and their applicability and usefulness discussed. The detection Limits (S/N = 3) for all investigated compounds, in both modes of detection, ranged between 1.5 and 7.5 pmol injected. Linear dynamic ranges spanned over four and three orders of magnitude when the composite electrode was used in the DC or pulsed mode. The main advantage of the Au-Ni composite electrode is that detection selectivity can be tailored by the choice of the detection mode and by the polarisation potential. As an example, we show how to detect common carbohydrates in tea powder using the constant potential detection mode. (C) 1999 Elsevier Science B.V. All rights reserved.