Anomalous conductivity zones in electrophoresis. III. Experimental tests of the theory

An assumption used in developing the basic theory, that ionic retardation factors are substantially independent of solute concentration, is tested and found valid. The results of electrophoresis through 15% polyacrylamide gels are found to be in agreement with the theory. Zones of altered concentration appear in the presence of spermine tetrahydrochloride, sodium phosphate buffer (pH 7.2) or Tris‐HCl (pH 7.0). The use of ionic retardation factors and transport numbers deduced from conductivity measurements leads to correct prediction of the sign of concentration change in each case. The direction and velocity of migration of a low‐concentration boundary can also be predicted, together with associated changes in pH. Further confirmation comes from a detailed analysis of published work on electrophoresis through sucrose gradients. The theoretical treatment is suitable for application to other systems (such as isoelectric focusing and isotachophoresis) where a gel is used as a stabilizing medium, and where effects of the kind discussed may produce unexpected distubances.