Chromatographic Detectors in Systems of Three Components

The chromatographic theory for the adsorption in binary systems has been well-established over the years. A binary mixture of known composition flows through a column packed with adsorbent. The system is then disturbed by adding a pulse of one of the pure components, and this causes a composition front to travel through the column. The retention time of this composition front is measured with a detector. This retention time can be related to the isotherm gradients of the two components. The situation is more complicated for a system of three components. In this case there are two composition fronts, and it is not easy to relate the retention times to the three isotherm gradients. In this preliminary investigation, we present a new theory to show how by using another composition detector, it is possible to evaluate the composition retention time for each component. We present some data for the ethane-ethylene-helium-13X zeolite system, and show that a simple detector based on the measurement of viscosity might be suitable.