Abstract: In the capillary electrophoretic system, the components of a sample to be separated and detected are labelled by a radioactive material which emits gamma rays or beta particles with energy high enough to penetrate the electrolyte and the capillary tube. A semiconductor detector outside the tube and placed adjacent to the tube detects the gamma rays or beta particles in order to detect the presence of the components of the sample. A weaker radio-label may also be used in conjunction with scintillating material which is introduced together with the sample into the tube or through a different tube. Alternatively, the scintillating material may be placed inside the tube or made a part of the tube. The scintillating material emits light in response to radiation from the radio labels on the components of the sample to enable detection of the component.