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backgrovind solution^. This electrical force has been used in several 

 arrangements providing one-way and transverse migrations,, From their 

 close relationship to chromatographic techniques, these methods have 

 become known as one-way electrochromatography, two-way electrochroma- 

 tography, and continuous electrochromatography^'^. Different modifi- 

 cations of these methods were devised independently by several workers 

 with various points of view. As a result, some of these methods are 

 now known by various semidescriptive synonyms such as zone electropho- 

 resis, eleotropherography, paper electrophoresis, and ionography^>-'> . 

 A few effective separatory procedures that are remotely related 

 to chromatography also belong in this category of differential migra- 

 tion analysiSc The consideration of chromatography as a differential 

 migration method of analysis has thus provided effective concepts for 

 the development and correlation of mai^ analytical techniques^* °S IV, 10, 



ELECTROCHROMATOGRAPHY 



Differential Electrical Migration 



Long employed to measure the electrical mobility of ions and to 

 indicate the complexity of mixtures, differential electrical migration 

 has only recently been widely employed as a separatory technique » 

 With a solution extending continuously between two electrodes, as in- 

 dicated by Figure V,l, electrolysis alters the proportions of the ions 

 at the electrodes and provides an indication of the mobilities of the 

 ionso With a wide zone of the mixture in a backgroimd electrolytic 

 solution extending to each electrode, electrolysis produces a partial 

 separation of the ions so that the overlapping zones provide an indication 



