The layout of the CE/amperometric microsystem used in this study has been described previously [19]. The CE microchip was placed in a laboratory-built Plexiglas holder fabricated for holding the separation chip and housing the detector and reservoirs. Thus, the setup allows a convenient replacement. Platinum wires were inserted into each reservoir, served as contacts for the high voltage power supply. Short pipette tips were cut and placed in each of the three holes on the glass chip for solution contact between the channel on the chip and corresponding reservoir on the chip holder. The amperometric detector, placed in the waste reservoir (at the channel outlet side), consisted of an Ag/AgCl wire reference, a platinum wire counter, and modified carbon paste working capillary electrode was placed opposite the channel outlet.