Performance of Pyrolyzed Photoresist Carbon Films in a Microchip Capillary Electrophoresis Device with Sinusoidal Voltammetric Detection

Abstract

Pyrolyzed photoresist films (PPF) are introduced as planar carbon electrodes in a PDMS-quartz hybrid microchip device. The utility of PPF in electroanalytical applications is demonstrated by the separation and detection of various neurotransmitters. PPF is found to form a stable, low-capacitance, durable layer on quartz, which can then be used in conjunction with a microchip capillary electrophoretic device. Sinusoidal voltammetric detection at PPF electrodes is shown to be very sensitive, with a detection limit (S/N = 3) of 100 nM for dopamine, corresponding to a mass detection limit (S/N = 3) of 2 amol. The selectivity of analysis in the frequency domain is demonstrated by isolating each individual signal in a pair of analytes that are chromatographically unresolved. Effectively decoupling the electrophoresis and electrochemical systems allows the electrodes to be placed just inside the separation channel, which results in efficient separations (80 000-100 000 plates/m).

Electrochemical Detection for Capillary Electrophoresis Microchips: A Review

“…In this flow-by design, the surface of the band platinum electrode was parallel to the flow direction (e.g., Figure 1A). A similar design, employing a pyrolyzed photoresist carbon film as a planar carbon electrode, was described by Hebert et al [9]. This was accomplished by coating a fused quartz plate with the photoresist, patterning the electrodes, and pyrolyzing in a furnace filled with hydrogen and nitrogen for 60 min at 1000 8C.…”

Enhanced Microchip Electrophoresis of Neurotransmitters on Glucose Oxidase Modified Poly(dimethylsiloxane) Microfluidic Devices

“…This might lead to severe sample loss and poor separation efficiency compared with those fabricated with glass. For example, neurotransmitters such as dopamine (DA) and epinephrine (EP) failed to be completely separated on hybrid PDMS/ glass [23], PDMS/quartz [24] and PDMS/PDMS microchips [25], although they could be done well on glass ones [26 -29]. Thus, the surface modification is a critical issue for PDMS microfluidic devices in electrophoresis applications.…”

Pyrolyzed Photoresist Carbon Electrodes for Microchip Electrophoresis with Dual-Electrode Amperometric Detection

“…Recently, PPF electrodes have been evaluated as detectors for microchip CEEC [17,29]. The PPF electrodes have several potential advantages for microchip CE.…”

“…The first report of the use of a PPF electrode with microchip CEEC was published by . In this report, sinusoidal voltammetry was employed for the detection of four neurotransmitters [17].…”