Evaluation of frontal chromatograms

Frontal chromatograms were investigated at low effluent concentrations, and deviations from the pertinent theory of chromatography were found in that region. These deviations are explained by a prerun in the column occurring between column wall and adjacent vertical particle layer. A model was devised for adapting these deviations to a mathematical function. According to that model, frontal chromatograms have an additional inflection point at low effluent concentrations with coordinates defined by the geometry of the column and the particles of the column bed. These coordinates are only altered by a packing density leading to particle distortion; on the premises of a reproducible column packing, these values are neither affected by kinetic parameters nor by a deterioration of the active particle surface. The experimental verification shows that the model can be employed to describe frontal chromatograms up to the second inflection point, when the effluent concentration reaches half of the feed concentration. A technical application is indicated in the paper.