Capillary electrophoresis amperometric detector (CE-AD) microchip with new microchannel structure for miniaturization

A modified capillary electrophoresis with amperometric detector (CE-AD) was developed and operated to separate and detect the target analytes. The concept of miniaturized twisted microchannels was utilized in the new CE-AD chip. The fabrication of a smaller chip size was attained given the same effective capillary length of separation. The performance of the twisted microchannels incorporated in the CE-AD was compared with the previously reported straight CE micro-channel. At the same applied separation voltage, the transport of ionic species to the working electrode by straight capillary electrophoresis (CE) channel is faster than the CE channel with twisted configuration. Due to the curved corners of twisted channels, the ionic transport rate is slightly decreased since these zones are generally not affected by the separation electric field. Injection of analytes was performed by applying an electric field of 50 V/cm while the electrophoretic separation of the ionic species was performed by applying an electric field of 60 V/cm. The optimized potential difference between the working and reference electrodes was around 600 mV DC which influences the oxidation-reduction reaction. With the new CE-AD chip, 1 mM bisphenol A was detected with extended response time of 73 s as compared with that of CE-AD with straight microchannel of 41 s. Results revealed that twisted microchannels are effective to further miniaturize the existing straight channel CE-AD chip and had great potential to enhance the separation between target analytes.