Chapter 10 Pulsed Electrochemical Detection of Carbohydrates at Gold Electrodes Following Liquid Chromatographic Separation

Abstract

This chapter describes pulsed electrochemical detection (PED) of carbohydrates at gold (Au) electrodes following liquid chromatographic separation. PED technology has been developed to achieve the highly sensitive and reproducible detection of alditols, monosaccharides, and oligosaccharides at Au electrodes. Sensitivity of PED at Au electrodes is maximized under conditions of high alkalinity, and pH > 12 is commonly recommended. Whereas all carbohydrates yield a PED response, only aldoses (reducing sugars) can be detected selectively as a result of the judicious choice of detection potential within PED waveforms. The analytic impact of liquid chromatography (LC)-PED can be appreciated on the basis of the recognition that (1) carbohydrates are polar compounds and, therefore, are not easily separated by gas chromatography and (2) these compounds are aliphatic without conjugated bonding and, therefore, are not easily detected by conventional photometric or fluorometric techniques without a priori derivatizations to attach chromophoric functional groups. In addition, the use of pellicular polymeric ion-exchange phases has been most popular to achieve separations in LC-PED because their stability at pH extremes is most consistent with use of highly alkaline mobile phases required for maximum sensitivity in PED at Au electrodes.