This Poster gives complementary material to the Lecture “Visualization of Chromatographic Surprises – The Helfferich Paradox Revisited. Here we will give more information on the remarkable deformations of invisible zones in the most simple and chromatographic system, unknown for most chromatographer. It is like reviling the part of the iceberg that is invisible, under the water.We recently described that “the injected sample molecules are not always found in the peak”. This happens if a small excess of molecules is injected into a column equilibrated with the same kind of molecules. Only one single peak will appear on the chromatogram (the system peak) while the injected molecules elute later in an invisible zone. The latter zones can be visualized by smart, but tedious, experimental procedures using either tracers or enantiomers. The phenomenon which was predicted by Helfferich in Science around 40 years ago was recently experimentally proven by us for the first time.As we continued to investigate the phenomena we could see that invisible zones containing the injected molecules take on the most strange and deformed shapes at higher sample loads. We will further show that a similar type of phenomenon appears in frontal analysis which results in invisible break-through and desorption curves. Depending on the conditions, the invisible breakthrough curves become more or less deformed. We explain the effects with the help of computer simulations which show an excellent agreement with experimental profiles of peaks and fronts.

Single component, small perturbation

Experimental Proof of a Chromatographic Paradox: Are the Injected Molecules in the Peak? Jörgen Samuelsson, Patrik Forsén, Morgan Stefansson and Torgny Fornstedt. Analytical Chemistry 2004, 76(4). 953-958.

Single component, large perturbation

Invisible Analyte Peak Deformations in Single-Component Liquid Chromatography” by Jörgen Samuelsson, Robert Arnell and Torgny Fornstedt. Analytical Chemistry (2006) 78 2765-2771.

Single component, frontal analysis

Discovery of invisible extra fronts in single-component frontal analysis in liquid chromatography by Jörgen Samuelsson and Torgny Fornstedt. Journal of Chromatography A (2006) 1114, 53-61.

Multi-component, small perturbation

Validation of the Tracer Pulse Method for Multi Component Liquid Chromatography- a Classical Paradox Revisited. Robert Arnell and Torgny Fornstedt. Analytical Chemistry (2006) 78, 4615-4623.