Abstract: Proposed is a device for radiochromatographic analysis of mixtures of substances containing components tagged by radioactive isotopes, such as soft .beta.-isotopes comprising a chromatographic column, a detector of nuclear radiation and a chromatographic detector connected in series along the flow of the substance being analyzed. The detector of nuclear radiation is provided with a cell made as a tube with a scintillator applied onto its inner surface in the form of a solid layer. The tube is provided with movable means for sequentialy cooling and heating the same and a light detector which is movable along the length of the tube. In operation, upon introduction of the portion of the mixture being analyzed into the column, with the heater interacting with the tube, the heater and cooler are moved so that by the time the last component of the mixture exits from the column, the cooler is in interacting relationship with the tube whereby the components of the mixture are frozen.