Evaluation of in‐channel amperometric detection using a dual‐channel microchip electrophoresis device and a two‐electrode potentiostat for reverse polarity separations

Abstract

In-channel amperometric detection combined with dual-channel microchip electrophoresis is evaluated using a two-electrode isolated potentiostat for reverse polarity separations. The device consists of two separate channels with the working and reference electrodes placed at identical positions relative to the end of the channel, enabling noise subtraction. In previous reports of this configuration, normal polarity and a three-electrode detection system were used. In the two-electrode detection system described here, the electrode in the reference channel acts as both the counter and reference. The effect of electrode placement in the channels on noise and detector response was investigated using nitrite, tyrosine, and hydrogen peroxide as model compounds. The effects of electrode material and size and type of reference electrode on noise and the potential shift of hydrodynamic voltammograms for the model compounds were determined. In addition, the performance of two- and three-electrode configurations using Pt and Ag/AgCl reference electrodes was compared. Although the signal was attenuated with the Pt reference, the noise was also significantly reduced. It was found that lower LOD were obtained for all three compounds with the dual-channel configuration compared to single-channel, in-channel detection. The dual-channel method was then used for the detection of nitrite in a dermal microdialysis sample obtained from a sheep following nitroglycerin administration.

Rapid and inexpensive method for the simple fabrication of PDMS‐based electrochemical sensors for detection in microfluidic devices

“…The production of the silicon mold used for prototyping the PDMS microfluidic devices was performed according to a well‐established protocol described elsewhere . The single‐T PDMS microchips used here were produced through mixing the PDMS monomer and its curing agent at the 9:1 ratio and then depositing this polymer mixture over the silicon mold.…”

“…Several types of materials can be employed as electrochemical sensor and coupled to ME for amperometric detection. The most used are metallic electrodes such as platinum and gold , and carbon‐based electrodes in the form of pencil graphite lead , carbon‐ink , composite , carbon fiber , and carbon paste . In comparison with metallic electrodes, the carbon‐based sensors have advantages such as lower cost, larger availability, higher chemical stability, lower overpotential, and wider potential working range .…”

Pencil graphite leads as simple amperometric sensors for microchip electrophoresis

“…The fabrication of the silicon mold used for prototyping the PDMS microfluidic devices was based on a well‐established method and performed according to a protocol described elsewhere . The single‐T PDMS microchips used in this work were fabricated through mixing the PDMS monomer and its curing agent at 9:1 ratio (w/w) and then depositing the polymer mixture over the silicon mold.…”

Multianalyte Physiological Microanalytical Devices

“…However, noise reduction techniques, such as in-channel detection and an electrically isolated potentiostat, can be implemented (39). ME with amperometric detection (Figure 2d ) has been used to detect redox active biomolecules, interfering species that are electroactive at the same potentials as target molecules (39)(40)(41)(42)(43)(44)(45)(46)(47), and to detect glucose by using a glucose oxidase-modified working electrode (41). Methods have been optimized to observe NO production in macrophages stimulated with lipopolysaccharide by analyzing NO 2 − ions (42) and dopamine (DA) metabolites from rat brain slices (46).…”