The design of conductivity and permittivity detection devices for electrophoresis

Abstract

Electrophoresis has been a major method for research in the life sciences for almost sixty years. The importance of this method is that it is one of the most powerful methods available for the separation of charged biomolecules.

Since Tiselius introduced electrophoresis as an analytical tool in 1930, there have been many variations in the development of this technique. Other techniques are presently being studied to furnish more suitable methodology for analyzing biopolymers. For example, the capability of electrophoresis in the analysis of biopolymers has recently been compared with High Performance Liquid Chromatography. Through the use of laboratory computers and commercialized instruments, automated versions of electrophoresis, therefore, seem more desirable. Several traditional electrophretic separation schemes have involved the use of support media such as gels. These techniques are slow, prone to poor reproducibility, and are not competitive with state-of-the-art methods found in some commercial methods. Modern detectors offer features such as sample preservation, selectivity for the analyte, dynamic range, low cost and convenience. Since a great deal of research has been done in the area of detectors for liquid chromatography, technology is available to provide very sensitive devices in the area of capillary zone electrophoresis. Since zone electrophoresis is the for most commonly used in clinical labs, interest was focused on developing an automated form in which a conductivity detector is placed directly over the cellulose acetate support medium. This procedure involved the analysis of serum hemoglobin. The result was that the hemoglobin fractions were affected by the detector and discrete zones did not form. A high frequency method was also attempted with similar results. There have been recent developments in capillary zone electrophoresis/conductivity detection. However, there are still questions concerning the use of these methods as universal detectors applicable to biomolecules. Permittivity detectors are also being investigated to research the use of these devices in capillary zone electrophoresis.