Fractionation of carrier ampholytes in multicompartment electrolyzers with isoelectric membranes

Multicompartment electrolyzers with isoelectric membranes can be successfully utilized for the preparation of carrier ampholytes of narrow pH ranges from commercially available wider pH intervals. An example is given on the preparation of a 0.6 pH unit (pH 6.7-7.3) range from a standard pH 6-8 interval. A 10% Ampholine solution is focused in an electrolyzer equipped with the following isoelectric membranes: pI 6.0, 6.7, 7.3 and 8.0. The narrow pH 6.7-7.3 cut can be efficiently utilized for base-line separation and quantitation of hemoglobin A from its glycated form, Hb A1c. This analysis is important for the screening and follow up of diabetic patients. The advantage of multicompartment electrolyzers are: (i) precision in the preparation of narrow pH cuts, due to the presence of membranes with defined pI values; (ii) ability to perform in both small- and large-scale operations and (iii) absence of contaminants leaching from granulated supports, as typical of some previous techniques.