SEPARATION OF NEUTRAL COMPOUNDS AND BASIC DRUGS BY CAPILLARY ELECTROPHORESIS IN ACIDIC SOLUTION USING LAURYLPOLY(OXYETHYLENE) SULFATE AS ANADDITIVE

Working at pH 2.4 with uncoated silica capillaries has the advantage t hat electroosmotic now is virtually eliminated. Excellent separations of protonated organic bases were obtained when ethanesulfonic acid was added to the running electrolyte to coat the capillary surface by a d ynamic equilibrium. The effect of adding a new surfactant, sulfonated Brij-30, to the acidic electrolyte was also investigated. Use of this surfactant in acidic organic-aqueous solutions changes the elution ord er of many organic cations and also permits the separation of neutral organic compounds. Excellent resolution of a mixture of 19 PAHs and si milar compounds was obtained in 40% organic solvent in only 20 min. Th e largest organic compounds form the most stable association complexes with the sulfonated Brij-30 and, thus, have the shortest migration ti mes. It is shown that the type and concentration of surfactant, as wel l as the composition of the aqueous-organic solution, are conditions t hat can be varied over a broad range to obtain superior separations of both neutral and cationic organic compounds. The type of organic solv ent is yet another condition that can be manipulated advantageously. F or example, the use of equal volumes of acetonitrile and 2-propanol in water-organic solutions can give better resolution of neutral organic analytes than either solvent used alone.