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 amperom etric detection in capillary electrophoresis (CE). Chemically modified sol- gel carbon composite electrodes (CCEs) containing cuprous oxide exhibit a s ensitive electrocatalytic response for the oxidation of carbohydrates. The electrochemical pretreatment at + 1.80 V (vs. SCE) for 60 s results in a ma rked 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 al so investigated in CE experiments. The peak current reproducibility with th is preanodized electrode over a period of 10 h was within 5 %. Calibration was linear over the concentration range from 2 to 400 mu M with the limits of detection for the carbohydrates studied in the range of 0.75-1.3 mu M.