Fast determination of sugars in Coke and Diet Coke by miniaturized capillary electrophoresis with amperometric detection

Abstract

The fast separation capability of a novel miniaturized capillary electrophoresis with amperometric detection (CE‐AD) system was demonstrated by determining sugar contents in Coke and diet Coke with an estimated separation efficiency of 60,000 TP/m. Factors influencing the separation and detection processes were examined and optimized. The end‐capillary 300 μm Cu wire amperometric detector offers favorable signal‐to‐noise characteristics at a relatively low potential (+0.50 V vs. Ag/AgCl) for detecting sugars. Three sugars (sucrose, glucose, and fructose) have been separated within 330 s in a 8.5 cm length capillary at a separation voltage of 1000 V using a 50 mM NaOH running buffer (pH 12.7). Highly linear response is obtained for the above compounds over the range of 5.0 to 2.0×10² μg/mL with low detection limit, down to 0.8 μg/mL for glucose (S/N = 3). The injection‐to‐injection repeatability for analytes in peak current (RSD < 3.6%) and for migration times (RSD < 1.4%) was excellent. The new miniaturized CE‐AD system should find a wide range of analytical applications involving assays of carbohydrates as an alternative to conventional CE and μ‐CE.