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Isoelectric buffers, part 3: Determination of p K a and p I values of diamino sulfate carrier ampholytes by indirect UV‐detection capillary electrophoresis
Author(s) -
Lalwani Sanjiv,
Tutu Edward,
Vigh Gyula
Publication year - 2005
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200500002
Subject(s) - chemistry , isoelectric focusing , capillary electrophoresis , chromatography , electrophoresis , absorbance , ammonium sulfate , pi , analytical chemistry (journal) , ionic strength , electrolyte , isoelectric point , aqueous solution , biochemistry , electrode , enzyme
Abstract Ampholytes with close p K a values ( i.e. , good carrier ampholytes (CAs)) are needed as buffers in pH‐biased isoelectric trapping (IET) separations. The syntheses of two families of such good CAs were reported recently. Members of the family of diamino sulfate ampholytes (first series) had p I values in the 5.7 < p I < 9.0 range. Members of the family of quaternary ammonium dicarboxylic acid ampholytes (second series) had p I values in the p I < 4.3 range. To further characterize the diamino sulfate ampholytes, their effective mobilities were measured by indirect UV‐absorbance detection capillary electrophoresis in a series of background electrolytes (BGEs) with different pH values. The p K a and limiting ionic mobility values of the CAs were obtained by fitting these mobility values, as a function of the pH and the ionic strength of the BGEs, to the theoretical mobility expression. These diamino sulfates complete the list of CAs suitable for IET separations.