Electrochemical Detection for Capillary Electrophoresis Microchips: A Review

Kinetic Monitoring of Electrophoretically Induced Solute Reaction by Axial Absorption Detection with Liquid-Core Waveguide

Teflon AF-2400 capillary has been used for capillary electrophoretic separation as well as for liquid-core waveguide for axial absorption detection. This separation/detection scheme has allowed continuous monitoring of electrophoretically induced reactions. In this paper, the decomposition of Cd2+ complex with 4-(2-pyridylazo)resorcinol has been tested, and its decomposition kinetics has been studied. A simple modeling has predicted the single-exponential decay of the absorbance detected by the present axial absorption detector and has allowed the estimation of the decomposition rate constant for this reaction.

Fabrication of microfluidic devices using dry film photoresist for microchip capillary electrophoresis

An inexpensive, disposable microfluidic device was fabricated from a dry film photoresist using a combination of photolithographic and hot roll lamination techniques. A microfluidic flow pattern was prefabricated in a dry film photoresist tape using traditional photolithographic methods. This tape became bonded to a poly(methyl methacrylate) (PMMA) sheet with prepouched holes when passed through a hot roll laminator. A copper working electrode and platinum decoupler was readily incorporated within this microchip. The integrated microchip device was then fixed in a laboratory-built Plexiglas holder prior to its use in microchip capillary electrophoresis. The performance of this device with amperometric detection for the separation of dopamine and catechol was examined. The separation was complete within 50 s at an applied potential of 200 V/cm. The relative standard deviations (RSD) of analyte migration times were less than 0.71%, and the theoretical plate numbers for dopamine and catechol were 3.2 x 10(4) and 4.1 x 10(4), respectively, based on a 65 mm separation channel.

Pulsed amperometric detection with poly(dimethylsiloxane)-fabricated capillary electrophoresis microchips for the determination of EPA priority pollutants

A miniaturized analytical system for separation and detection of three EPA priority phenolic pollutants, based on a poly(dimethylsiloxane)-fabricated capillary electrophoresis microchip and pulsed amperometric detection is described. The approach offers a rapid (less than 2 min), simultaneous measurement of three phenolic pollutants: phenol, 4,6-dinitro-o-cresol and pentachlorophenol. The highly stable response (RSD = 6.1%) observed for repetitive injections (n > 100) reflects the effectiveness of Au working electrode cleaned by pulsed amperometric detection. The effect of solution conditions, separation potential and detection waveform were optimized for both the separation and detection of phenols. Under the optimum conditions (5.0 mM phosphate buffer pH = 12.4, detection potential: 0.7 V, separation potential: 1200 V, injection time: 10 s) the baseline separation of the three selected compounds was achieved. Limits of detection of 2.2 microM (2.8 fmol), 0.9 microM (1.1 fmol), and 1.3 microM (1.6 fmol) were achieved for phenol, 4,6-dinitro-o-cresol and pentachlorophenol, respectively. A local city water sample and two over-the-counter sore-throat medicines were analyzed in order to demonstrate the capabilities of the proposed technique to face real applications.