End-column amperometric detection of aesculin and aesculetin by capillary electrophoresis

Abstract

Determination of aesculin (AL) and aesculetin (AT) by capillary electrophoresis with end-column amperometric detection using a 33 μm microdisk carbon fiber electrode is described. The HDVs, the effect of pH, buffer concentration, injection voltage, injection time and separation voltage on the peak current response ( i p) of the analytes and the number of theoretical plates ( N) were studied. The method has high sensitivity and good reproducibility. Under the optimum condition — 10 mM, pH 9.00 phosphate buffer, 4 s at 9 kV injection, separation at 15 kV and +1.0 V as the detection potential — low detection limits ( S/ N = 3) of 0.06 and 0.3 μM were obtained for AL and AT, respectively. The calibration curve was linear over three orders of magnitude. The relative standard deviations ( n = 15) of peak current and migration time were 3.9% and 4.6%, and 0.96% and 0.75% for 15 consecutive injections of 5 μM AL and AT, respectively. The use of this method for the separation and detection of the two compounds present in the traditional Chinese medicine and human urine samples is also reported.