. 119 - 



usually between OoOl and 0„1 M<, Various complexing agents have been 

 added to the background solution in order to improve the separability 

 of many substanceso For example, polybasic acids form anionic complexes 

 with polyvalent cations but not with monovalent cations thereby faoili= 

 tating the separation of these complexed cations from the nonoomplexed 

 monovalent cations9 (Figure Vj,6) „ 



Many different supports have been employed for the electrochroma- 

 tographic apparatus^'", particularly for the migration systems (Table 

 V,l)o Moist paper strips have been suspended horizontally on glass 

 points in a closed cooled atmosphereo They have been suspended over a 

 glass rod as an inverted V, They have been suspended in a cooled, non= 

 conducting organic liquid such as chlorobenzene^*^' » The moist paper 

 has also been placed between glass or plastic plates, between water= 

 cooled glass vessels"''* , or between polyethylene sheets on a water=- 

 cooled stainless steel tank' o 



Dete ct i on of Separated Substances 



Substances separated by electrochromatography are easily detected, 

 isolated, and estimated by means of the methods previously employed 

 with chromatography, particularly with paper chromatography5„ (See 

 Lecture IVo) The availability of these detection and estimation tech- 

 niques contributed, in large measure, to the rapid application of paper 

 electrochromatography^ * o 



The great majority of the detection methods are based upon chemi- 

 cal reactions that yield colored products-^^s°= Nuclear methods, in- 

 cluding radioactive tracer techniques and neutron activation before 

 and after migration, have been employed with substances containing 



