Determination of Sugars Using Ligand-Exchange Capillary Electrophoresis

The capabilities of the ligand-exchange capillary electrophoresis mode (working electrolyte, 1 mM copper(II) and 175 mM NH3; 30 mbar, 10 s; +25 kV; 245 nm; 20 degrees C) for the determination of sugars (glucose, fructose, and sucrose) in real samples (fruit juices, wines, and drug preparations) were studied. With the use of glucose as an example, the detection limits for direct (as sugar-copper(II) complexes; 245 nm) and indirect (working electrolyte, 5 mM tryptophan and 50 mM NaOH; 30 mbar, 10 s; + 10 kV; 280 nm; 20 degrees C) UV detection were compared: similar to 21 and similar to 8 mg/L (for direct and indirect detection, respectively).