EFFECT OF ORGANIC-SOLVENTS ON THE SEPARATION OF BENZOIC-ACIDS BY CAPILLARY ELECTROPHORESIS

The effect of organic modifiers on the separation of a number of close ly related isomeric benzoic acids by capillary electrophoresis is desc ribed. It is shown that while a single modifier concentration cannot h elp resolve the entire electropherogram, organic modifiers do signific antly enhance the resolution of parts of the separation system by comp arison with 40 mmol l(-1) phosphate buffer. The effects on separation and retention times are discussed in terms of the effects on electroos motic flow and the electrophoretic mobilities of the charged solutes. The effects were found to be modifier specific, although the trends we re in the same direction (Le., decreasing electroosmotic flow with inc reased percentage of organic modifier). The major influence is the man ipulation of the electroosmotic mobility.