Carbon paste-based electrochemical detectors for microchip capillary electrophoresis/electrochemistry

Abstract

The first reported use of a carbon paste electrochemical detector for microchip capillary electrophoresis (CE) is described. Poly(dimethylsiloxane) (PDMS)-based microchip CE devices were constructed by reversibly sealing a PDMS layer containing separation and injection channels to a separate PDMS layer that contained carbon paste working electrodes. End-channel amperometric detection with a single electrode was used to detect amino acids derivatized with naphthalene dicarboxaldehyde. Two electrodes were placed in series for dual electrode detection. This approach was demonstrated for the detection of copper(II) peptide complexes. A major advantage of carbon paste is that catalysts can be easily incorporated into the electrode. Carbon paste that was chemically modified with cobalt phthalocyanine was used for the detection of thiols following a CE separation. These devices illustrate the potential for an easily constructed microchip CE system with a carbon-based detector that exhibits adjustable selectivity.

Microchip Capillary Electrophoresis-Electrochemistry with Rigid Graphite-Epoxy Composite Detector

“…Calculated detection limits (based on S/N ¼ 3) are 320 nM for dopamine and 400 nM for catechol. Such detection limits are lower than those reported for mCE-EC systems with carbon thick-film screen-printed [14] or carbon paste detectors [5]. Such improvements can be attributed to the low noise level and enhanced mass transport of new mCE-GEC microsystem.…”

“…The composite electrodes act as arrays of microelectrodes, they show the response comparable to the conventional electrodes but with low noise level [9]. So far, there were published only two reports on use of carbon paste composite electrodes for detection in microfluidic systems [5,6]. However, there is no report on the use of the rigid carbon composites, which have favorable mechanical stability properties compared to carbon pastes [10] in microchip electrophoresis-electrochemistry (mCE-EC).…”

“…The various parameters of the microchip electrophoresis-rigid graphite-epoxy composite detector were optimized. [5,6]. Particularly, conducting composites are materials that were widely utilized for electrochemical detection of organic compounds in flowing liquids (i.e., FIA, HPLC) [7,8].…”

Electroanalytical Flow Measurements–Recent Advances

“…Applications of a developed system for fast separation of neurotransmitters, and with indirect electrochemical detection of high-sensitivity DNA restriction fragments and PCR product sizing were demonstrated. In another fully integrated microdevice a polymer based microfluidic was equipped with one or two working carbon paste electrodes [226]. For various configuration of a detector CE separation and detection of amino acids derivatized with naphthalene dicarboxaldehyde, copper(II) peptide complexes and thiols were demonstrated.…”

"Fabricação e avaliação de microdispositivos para eletroforese com detecção eletroquímica"

“…Susan M. Lunte [63,76] demonstraram a utilização destes eletrodos na separação de carboidratos e aminoácidos usando uma configuração de dois eletrodos, proposta anteriormente pelo mesmo grupo [58]. Lee e Chen [67] também demonstraram a separação para diversos aminoácidos utilizando eletrodos de Cu.…”