942 (2001) 237–248 Journal of Chromatography A, www.elsevier.com / locate / chroma Solute–solvent interactions in micellar electrokinetic chromatography III. Characterization of the selectivity of micellar electrokinetic q chromatography systems a a a b a, * ` ´ ´ Elisabet Fuguet , Clara Rafols , Elisabeth Bosch , Michael H. Abraham , Martı Roses a ´ ´ Departament de Quımica Analıtica, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Spain b Chemistry Department, University College London, 20 Gordon Street, London WC1H 0AJ, UK Received 12 June 2001; received in revised form 9 October 2001; accepted 9 October 2001 Abstract Several micellar electrokinetic chromatography (MEKC) systems (sodium dodecyl sulfate, lithium dodecyl sulfate, lithium perfluorooctanesulfonate, sodium cholate, sodium deoxycholate, tetradecyltrimethylammonium bromide and hexadecyl- trimethylammonium bromide) have been characterized by means of the solvation parameter model. It has been observed that the coefficients of the correlation equations depend strongly on the particular set of compounds analyzed. Principal component analysis has been used to characterize the 2975 compounds with available solute descriptors and to select an appropriate subset of compounds to be analyzed by MEKC. With this set of compounds, the MEKC systems have been characterized. Principal component analysis has also been used to show the similarities and differences between the properties of the surfactants characterized by MEKC.  2002 Elsevier Science B.V. All rights reserved. Keywords: Micellar electrokinetic chromatography; Solute descriptors; Linear solvation energy relationships; Principal component analysis; Micelles; Selectivity; Surfactants 1. Introduction 3]. The uncharged molecules are separated according to their distribution between the aqueous phase and Micellar electrokinetic chromatography (MEKC) the micellar phase. In the case of charged solutes a is a powerful technique for the separation of mix- combination of distribution between phases and tures of uncharged and / or charged compounds [1– electrophoretic mobility is the reason of their sepa- ration. Migration behaviour and separation by MEKC can be easily modified through proper selec- q Presented at the 30th Scientific Meeting of the Spanish Group tion of the surfactant type, adding different complex- of Chromatography and Related Techniques / 1st Meeting of the ing agents (cyclodextrins, urea, chiral additives, etc.) Spanish Society of Chromatography and Related Techniques, or adding organic solvents to the separation buffer Valencia, 18–20 April 2001. [4–6]. Since the chemical nature of the pseudo- *Corresponding author. Tel.: 134-93-402-1796; fax: 134-93- stationary phase has a major influence on solute– 402-1233. ´ E-mail address: marti@apolo.qui.ub.es (M. Roses). micelle interaction, it is generally agreed that the 0021-9673 / 02 / $ – see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S0021-9673(01)01383-8