Amperometric Detection of Carbohydrates by Capillary Electrophoresis with a Cuprous Oxide Modified Sol-Gel Carbon Composite Electrode

A new sensitive electrochemical detector has been developed for the amperometric detection in capillary electrophoresis (CE). Chemically modified sol-gel carbon composite electrodes (CCEs) containing cuprous oxide exhibit a sensitive electrocatalytic response for the oxidation of carbohydrates. The electrochemical pretreatment at +1.80 V (vs. SCE) for 60 s results in a marked enhancement of the current responses for all sugars examined, compared to the untreated electrode. A sample mixture containing 8 different sugars was separated within 30 min at an optimal constant potential of +0.65 V (vs. SCE). The stability of an electrochemically preanodized Cu2O-CCE was also investigated in CE experiments. The peak current reproducibility with this preanodized electrode over a period of 10 h was within 5 %. Calibration was linear over the concentration range from 2 to 400 µM with the limits of detection for the carbohydrates studied in the range of 0.75–1.3 µM.