Abstract: A double beam photometric flow cell for high pressure liquid chromatography having illuminated sample and reference passageways therein, the sample passageway receiving flowing fluid sample fractions for analysis. Regulating apertures control the relative amount of light passed through the passageways such that the light energy through the reference passageway exceeds that through the sample passageway. This reduces the contribution of the reference path to "shot noise" in the photometer output signal.

Abstract: A photometric flow cell for high pressure liquid chromatography having an illuminated passageway therein between open ends of which fluid samples are flowed for analysis. An annular, porous flow impedance element is supported in an annular channel surrounding one end of the passageway. The impedance element reduces turbulence of flow through the open end by evenly distributing the flowing fluid circumferentially about the end opening.

Abstract: In a high-pressure liquid chromatography system, a radioactive sample in the effluent from a chromatographic column can be detected by passing the effluent into a cell packed with a fluorescent composition comprising a scintillation material chemically bonded to an inert substrate. A suitable fluorescent composition is microparticulate didansyl-N-2-aminoethyl-3-aminopropyl silica. Radioactive emissions from the sample cause scintillations in the fluorescent composition that can be detected through the walls of the cell. In order to obtain a chromatogram of the radioactivity occurring in the column, aliquots of the effluent from the column may be passed sequentially into a plurality of cells arranged on a carousel support structure that is rotable in stepwise fashion so that each cell passes in turn through a fill station, a detection station, and a wash station. At the fill station, each cell in turn is filled with an aliquot of effluent.