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/deposi tion of nickel hydroxide on the gold surface was characterised. The resulti ng composite electrode was evaluated as an amperometric sensor in flow inje ction analysis and anion-exchange chromatography for the quantitation of al ditols and simple carbohydrates. Constant potential detection at +0.6V vs A g/AgCl and a pulsed detection mode were employed, and their applicability a nd usefulness discussed. The detection Limits (S/N = 3) for all investigate d compounds, in both modes of detection, ranged between 1.5 and 7.5 pmol in jected. Linear dynamic ranges spanned over four and three orders of magnitu de 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 c an 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 Scie nce B.V. All rights reserved.