Comparison of different conductivity detector geometries on an isotachophoresis PMMA-microchip

Abstract

Conductivity detection is one of the most often employed means of detection in isotachophoresis. In microanalytical devices, thin-film platinum electrodes can be used for conductivity detection and for other electrochemical methods of detection. The design and the performance of different electrode geometries for on-column contact conductivity detection with thin-film platinum electrodes integrated on an isotachophoresis PMMA-microchip is described. Three different electrode geometries for direct conductivity detection were used for the investigation of isotachophoretic separations. The influence of the width of the electrodes and their positioning relative to the separation channel was investigated. The performance of the different detectors is compared for the analysis of organic carboxylic acid anions.

Recent developments in electrochemical detection for microchip capillary electrophoresis

“…Therefore, less band-broadening due to diffusion will occur, leading to a more efficient separation and better peak shapes. Also, several detectors can be located along the separation channel, making it possible to monitor the analyte zones at various locations along the channel [85][86][87][88]92]. An example of these devices is shown in Fig.…”

“…Grab et al investigated a variety of electrode geometries for a poly(methyl methacrylate) (PMMA)-based microchip isotachophoresiscapillary zone electrophoresis (ITP-CZE) device with oncolumn contact conductivity detection [92]. The separation channels were constructed in the substrate using micromilling and hot embossing techniques.…”

“…ITP [89][90][91][92] has also been used with conductivity detection as a separation technique either alone or in conjunction with CZE [86,88]. This technique has been used for a variety of applications including the isolation of the drug valproic acid from human serum [87].…”

Analysis of inorganic and small organic ions with the capillary electrophoresis microchip

“…Graß and co-workers [55] employed the same microchip design in their evaluation of the performance of different detector configurations using ITP separation methods. Three different electrode designs were constructed and tested by analyzing seven organic carboxylic acid anions.…”

Isotachophoresis of β‐blockers in a capillary and on a poly(methyl methacrylate) chip

“…The microchip system used in the present study consists of a poly(methyl methacrylate) (PMMA) microchip with integrated platinum electrodes for conductivity detection and power supply [23,24]. The microchip has two separation channels in a coupling arrangement, which allows a two-step separation to be performed on a single chip.…”