Abstract: An on-column detector for electrophoresis samples based on the principles of potential gradient detection, in which the electrodes for detection are physically isolated from the electrophoretic separation process, but maintains the same electrical potential as the corresponding interior of the electrophoretic separation channel. Potential gradient detection is used to measure the applied electrical field at two points within the electrophoretic channel during electrophoresis. When sample components with conductivity different from the electrophoretic medium passes between these two points, it causes a change in the potential gradient between the two points, which would be sensed by the sensing electrodes of the detector and registered by a data acquisition system. The apparatus can make use of conventional separation channel as well as separation channels on microchips.

Abstract: An optical detection system comprising an electromagnetic radiation source, a source radiation focusing and collimating means, a photodetector, an emitted radiation focusing means and a source radiation blocking panel. The radiation source is used to direct source radiation onto a sample which is disposed in a sample platform. The source radiation focusing and collimating means is disposed between the radiation source and the sample for focusing and collimating the source radiation onto the sample. The photodetector is adapted for receiving radiation emitted from the sample which has been focused by the emitted radiation focusing means. The source radiation blocking panel, disposed between the source radiation focusing and collimating means and the sample, is unique in that it is capable of reducing light scattering and interference, such that a clear signal from each individual sample can be obtained by the photodetector.