SIMULTANEOUS DETERMINATION OF CARBOHYDRATES AND AMINO-ACIDS BY CAPILLARY ZONE ELECTROPHORESIS WITH CONSTANT POTENTIAL AMPEROMETRIC DETECTION AT A COPPER ELECTRODE

Capillary zone electrophoresis with end-column amperometric detection at a copper microdisk electrode (100 mu m in diameter) was successfull y applied for simultaneous determination of carbohydrates and amino ac ids. Under the separation voltage of 27 kV and the separation electrol yte of 80 mM NaOH in a 75 cm fused silica capillary (10 mu m i.d. x 37 5 mu m o.d.), complete separation of a standard mixture containing 9 c arbohydrates and 12 amino acids was achieved in less than 25 min. With the electrokinetical injection of 5.4 s at 27 kV and the detection po tential of 0.62 V vs. Ag/AgCl, the detection limits (S/N = 3) were 0.2 2-0.65 ppm (1.2-1.9 mu M) for carbohydrates and 0.31-6.5 ppm (2.3-39 m u M) for amino acids, respectively. The calculated numbers of theoreti cal plates were between 41,000 and 190,000. The use of this method for analysis of carbohydrates and amino acids in a urine sample was demon strated.