Chromatography solute movement analysis

Exanqile 18-2. Linear solute movement analysis of elution chromatography... 

There is an analogy that may be useful in understanding this solute movement analysis. The problems are similar to algebra problems where two trains start to leave a station at the same time, but with different velocities (u and Ug in chromatography). You want to calculate when each train arrives at a second station (a distance L away) and when the tail end of each train (analogous to the feed time, tp) leaves the second station. 

Spot test analysis makes frequent use of electrochemical separation methods. Especially in paper chromatography use is made of differential diffusion in which an electrical field serves to accomplish the desired separation. Of particular interest in spot test analysis is the employment of electrographic methods for examining metals, alloys and ores. The basic principle employed is the anodic solution of the metals. In practice, the specimen is made the anode and a piece of aluminum foil serves as cathode. Filter paper is moistened with the appropriate reagent solution and then placed between these two electrodes. The proper voltage is then applied. The movement of the metals then leads to an imprint on the paper and so reveals the exact position of the metals that have migrated from the surface of the test specimen. Hermance and Wadlow have published a comprehensive review of this procedure. 

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