Abstract: A chromatographic system including cassettes, each containing a separating column which is connected at each of its ends to a coupling piece having both of its ends in the form of conical surfaces on the outside of the cassettes. These conical coupling surfaces may be connected to complementary-shaped conical fittings in a fluid-tight manner to connect the inlet and outlet ends of the column of the chromatographic instrument lines such as, for example, the sample injector, stream splitter, backflushing inlet and outlet lines, detector and auxiliary gas flows. A special connection fitting allows the direct connection of the conical coupling surfaces of two column-containing cassettes, as well as connection to other parts of the chromatograph between the columns. Thus, the separating column cassettes may be utilized as components of various relatively simple and complex chromatographic systems.