Microchip capillary electrophoresis with amperometric detection for metal ion analysis

Abstract

This thesis demonstrates the fast and simultaneous detection of prominent heavy metals including lead, cadmium and cupper using a microchip capillary electrophoresis with electrochemical detection. Direct amperometric detection mode for microchip capillary electrophoresis was successfully applied to analytes, the heavy metal ions. The influences of the separation voltage, detection potential, concentration and pH value of running buffer on the response of the detector were carefully investigated and optimized. The zone electrophoretic separation of lead, cadmium and copper is less than 3 min using a MES buffer and L-Histidine as background electrolyte (pH 7.0, 25 mM), employing 1.2 kV as the separation voltage and -0.8 V as the detection potential. The detection limits for Pb2+, Cd2+, and Cu2+ were 1.74, 0.73 and 0.13 μM (S/N = 3), respectively. The %RSD of peak current was < 6 % and the %RSD of migration times <2% for prolong operation. To demonstrate the potential and future role of microchip CE, a new route in the real sample analysis was presented. The results obtained allow the proposed microchip capillary electrophoresis 9 electrochemical detection as a real gateway to microanalysis in foods.