Indirect moving-boundary method

Other methods related to the moving boundary method include the indirect moving boundary method (where the concentration in the trailing edge behind the boundary is monitored) and the analytical boundary method. The latter approach involves analysis of the compositional change within the moving boundary zone and is a hybrid of the Hittorf and standard moving boundary techniques. 

The detailed theory and mode of operation of the main experimental methods of obtaining transference numbers—Hittorf, direct and indirect moving boundary, analytical boundary, e.m.f. of cells with transference or of cells in centrifugal fields— have been published elsewhere. Only the features particularly pertinent to work with electrolytes in organic solvents will be dealt with here. 

The number of precise methods to measure transference numbers in liquid aqueous electrolytes is quite acceptable [9-14]. Various methods are already used for more than a hundred years, such as the moving boundary, Hittorf s method, or the indirect determination of transference numbers by conductivity measurements. In contrast, accurate data for nonaqueous liquid electrolytes, especially with respect to hthium salts, are very rare. In hterature, the most often used methods are the potentiostatic polarization method and determination by NMR [21, 22]. Interestingly, the first was developed for solid electrolytes the latter is only valid for ideal solutions. To measure concentrated electrolyte... 

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