Isoconductive Techniques

A quantitative statement regarding the increase of the elution strength when switching from one eluent to another may be derived from the equation proposed by Gjerde and Fritz [127] for calculating the background conductivity of 

Consider two eluents of different elution strength containing the same eluent anions but different cations with equivalent conductances Ai and A. Under iso-conductive conditions, the background conductivity, Gi, of the weaker eluent equals that of the stronger eluent G2. Given Gi = G2, Eq. (3.71) may be rearranged, so that the concentrations, Ci and C2, of both eluents are related to the corresponding equivalent conductivities  

Source Reproduced with permission from Ref. [199]. Copyright 1988, American Chemical Society. 

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In comparing the concentration gradient concept with subsequent chemical suppression, the chromatogram of various inorganic anions in Fig. 3-127 that was obtained with isoconductive eluents clearly shows the limitation of this technique. Although the analysis time for the separation shown is shorter than under isocratic conditions, an improvement in the resolution between the signals, especially in the first part of the... 

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