Microchip capillary electrophoresis with amperometric detection for several carbohydrates

Microchip capillary electrophoresis (muCE) with amperometric detection at Cu electrode benefited fast separation and direct detection of carbohydrates. The working electrode of 50-mum Cu wire attached nearly against the channel outlet-4 mum, where it benefited collecting detection current and suppressing overwhelming noise. The use of alkaline medium was essential to separating and detecting carbohydrates, which dissociated into the sensitive alcolate anions. The 10-cm serpentine chip, though lengthening the migration time, it provided better efficiency. Sucrose, cellobiose, glucose, and fructose migrated from the outlet in 400 s +2000 V. The linear calibration plots ranging from 10 to 1000 muM with regression coefficients better than 0.996 were obtained. The injection-to-injection reproducibility of 1.24% (n = 7) for glucose in peak current and 0.6% for migration times were excellent. The detection limit was low, down to 2.3 muM for glucose (SIN = 3) or 27.6 attomole in mass detection. (C) 2004 Elsevier B.V. All rights reserved.