title: A high-performance polycarbonate electrophoresis microchip with integrated three-electrode system for end-channel amperometric detection.
abstract: A fully integrated polycarbonate (PC) microchip for CE with end-channel electrochemical detection operated in an amperometric mode (CE-ED) has been developed. The on-chip integrated three-electrode system consisted of a gold working electrode, an Ag/AgCl reference electrode and a platinum counter electrode, which was fabricated by photo-directed electroless plating combined with electroplating. The working electrode was positioned against the separation channel exit to reduce post-channel band broadening. The electrophoresis high-voltage (HV) interference with the amperometric detection was assessed with respect to detection noise and potential shifts at various working-to-reference electrode spacing. It was observed that the electrophoresis HV interference caused by positioning the working electrode against the channel exit could be diminished by using an on-chip integrated reference electrode that was positioned in close proximity (100 microm) to the working electrode. The CE-ED microchip was demonstrated for the separation of model analytes, including dopamine (DA) and catechol (CA). Detection limits of 132 and 164 nM were achieved for DA and CA, respectively, and a theoretical plate number of 2.5x10(4)/m was obtained for DA. Relative standard deviations in peak heights observed for five runs of a standard solution containing the two analytes (0.1 mM for each) were 1.2 and 3.1% for DA and CA, respectively. The chip could be continuously used for more than 8 h without significant deterioration in analytical performance.
authors.affiliation: The Institute of Micro Analytical Systems, Department of Chemistry, Zhejiang University, Hangzhou, P. R. China.
authors.forename: Yurong
authors.initials: Y
authors.lastname: Wang
authors.forename: Hengwu
authors.initials: H
authors.lastname: Chen
authors.forename: Qiaohong
authors.initials: Q
authors.lastname: He
authors.forename: Steven A
authors.initials: SA
authors.lastname: Soper
mesh_terms: D002396:Catechols / Q000032:analysis; D004298:Dopamine / Q000032:analysis; D004560:Electricity; D004566:Electrodes; D046209:Electrophoresis, Microchip / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D011108:Polymers
chemical_list: D002396:Catechols; D011108:Polymers; C017902:lexan; C034221:catechol; D004298:Dopamine