INFLUENCE OF ORGANIC-SOLVENTS IN COELECTROOSMOTIC CAPILLARY ELECTROPHORESIS OF PHENOLS

The addition of organic solvents (methanol, ethanol, 1-propanol, 2-propanol, acetonitrile) as modifiers in capillary electrophoresis (CE) significantly improves peak shapes and enables the separation of positional isomers of substituted phenols. A reversal of the electroosmotic now (EOF) to reduce analysis time by migration of the anionic analytes in the same direction as the electroosmotic flow (coelectroosmotic CE) is achieved by using cetyltrimethylammonium bromide and 1,5-dimethyl-1,5-diazaundecamethylene polymethobromide (hexadimethrine bromide, HDB, Polybrene) as EOF modifiers. The influence of various organic modifiers on EOF, electrophoretic mobilities of the analytes, and theoretical plate numbers is investigated. A high pH value of the buffer electrolytes above the pK(A) value of the phenols is chosen. The impact of various organic modifiers and the influence of the chain length of the alcohols on the separation behavior of alkyl phenols is investigated.