Institute of Physical and Theoretical Chemistry

Conductivity and potential detection for capillaries and microfluidic channels

Conductivity detection represents a versatile and universal tool for electromigrative separation techniques, mainly regarding capillary zone electrophoresis and isotachophoresis. If a contactless setup is used for detection, very stable and reproducible measurements can be achieved since the electrodes are protected from potential contamination originating from matrix components. In conjunction with our cooperation partners we develop new detection systems for conductivity measurements in capillaries and on microfluidic chips with extremely high spatial resolution which is e.g. required for isotachophoresis. In case of multidimensional separations, conductivity detection is used to monitor the first separation dimension directly in the microfluidic chip-interface.

Sepation channels in a network can be closed electrokinetikally when there is no potential differences. However, if external system such as mass spectrometric detection or a fraction collector are used or if separations with changing conductivity in the separation channel are used, this cannot be achieved via calculations using Kirchhoffs laws. The only option for potential control is a potential measurement directly an intersection of channels and an adaptation of externally applied voltages. We reached a dynamic potential control using passivated electrodes, which do not disturb the separation process.

Publications:

1. On-chip intermediate potential measurements for the control of electromigration in multi-channel networks in case of time-dependent potential changes

D. Sydes, P.A. Kler, P. Zipfl, D. Lutz, H. Bouwes, C. Huhn, Sens. Actuat. B: Chem. 2017, 240, 330-337

2. Column coupling isotachophoresis/capillary electrophoresis with mass spectrometric detection: characterization and optimization of microfluidic interfaces

P. A. Kler, T. N. Posch, M. Pattky, R. M. Tiggelaar, C. Huhn*, J. Chromatogr. A 2013, 1297, 204-212

Cooperations:

  • Pablo Kler, Centro de Investigación de Métodos Computacionales (CIMEC), Universidad Nacional del Litoral (UNL), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Santa Fe, Argentina
  • Peter Zipfl, Optoelektronik, Hochschule Aalen, Aalen
  • Daniel Lutz, CalvaSens, Aalen