An Undergraduate Column Chromatography Experiment M. Danot, S. Nahmias, a n d U. Zoller Haifa University-Oranim, P. 0. Kiryat Tivon 36 910, Israel
Column chromatography is a basic technique in both oreanic and inoreanic laboratories. I n this e x ~ e r i m e n tunder. graduate stud& are introduced t o t h e theoreti'cal a n d technical asDects of column chromatoeranhv. T h e exweriments here presented combine the u s e o i c & m n chromatography and spectroscopy. T h e experiments have been designed specifically t o suit a n undergraduate laboratory in terms of duration, quick and complete separation of mixture components, and vivid colors of mixture components. One of t h e components leaves t h e column auickls. T h e other, however, leaves i t slowly, thus enahlingthe students t o draw a typical curve of component concentration versus t h e volume o f t h e fraction t h a t ieft the column. In a shortened form, the present experiment can serve a s a reliable demonstration of t h e column chromatography technique.
Chemicals iodine methylene hlue henzoic acid (optional) carhon tetrachloride dichloromethane ethanol
After the absorbance of each fraction is determined separately, all the collected fractions should he combined and mixed in a graduated cylinder and the absorbance of the entire ethanolic methylene hlue solution should he determined. The third (optional) component, henzoic acid, can he finallv eluted from the column wine water. (The pH of the first 10-mlportion of water whieh follows the cast ethiolic fraction is
