Determination of absolute mobilities and pK values by isotachophoresis

Once steady state is reached in isotachophoresis, all sample zones have a particular cond. for a given operational system. With a computer program, all combinations of abs. mobilities and pK values can be calcd. to give a well-defined zone cond. for a given electrolyte system. If these abs. mobilities are plotted as functions of their pK values, a relationship is obtained that is call an isoconductor. Isoconductors of different electrolyte systems intersect. By measuring the step-heights of an ionic species in 2 different electrolyte systems and by converting these step-heights into zone conductivities, the abs. mobility and pK value of that ionic species can be obtained from the intersection of the isoconductors concerned. Both in a graphic and computational way, abs. mobilities and pK values were detd. for some monovalent acids. The results agree with values available in literature. [on SciFinder (R)]