[ 15 ] M. Defernez, E.K. Kemsley, R.H. Wilson, J. Agric. Food Chem. 43 ( 1995 ) 109. [ 16 ] E.K. Kemsley, J.K. Holland, M. Defernez, R.H. Wilson, J. Agric. Food Chem. 44 ( 1996 ) 3864. [ 17 ] R. Briandet, E.K. Kemsley, R.H. Wilson, J. Agric. Food Chem. 44 ( 1996 ) 170. [ 18] R. Briandet, E.K. Kemsley, R.H. Wilson, J. Sci. Food Agric. 71 ( 1996 ) 359. [ 19 ] O. Al-Jowder, E.K. Kemsley, R.H. Wilson, Food Chem. 59 ( 1997 ) 195^201. [ 20 ] H. Rannou, G. Downey, Anal. Commun. 34 ( 1997 ) 401^ 404. [ 21] G. Downey, R. Briandet, R.H. Wilson, E.K. Kemsley, J. Agric. Food Chem. 45 ( 1997 ) 4357^4361. [ 22 ] Y.W. Lai, E.K. Kemsley, R.H. Wilson, Food Chem. 53 ( 1995 ) 95. [ 23 ] G. Downey, B. Spengler, Ir. J. Agric. Food Res. 35 ( 1996 ) 179. Dr Gerard Downey has been involved in the application of near infrared spectroscopy to food and agricultural problems for almost 20 years. He is currently Chairman- Elect of the International Committee for Near Infrared Spectroscopy and has been active in a number of European projects involving the use of spectroscopy for food analysis. His most recent interests with this technique have been in the area of mathematical model development for qualitative analysis of foods and food ingredients. In the last number of years he has begun to apply these chemometric techniques to mid-infrared spectroscopic data sets and also to spectra obtained by combining data from both regions. Analyte^additive interactions in nonaqueous capillary electrophoresis: a critical review Michael T. Bowser, Andrea R. Kranack, David D.Y. Chen* Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada This article reviews the recent developments in nonaqueous capillary electrophoresis and discusses the effect of the solvent on analyte^ additive interactions. When nonaqueous solvents are used, solvophobic interactions are generally weaker than those in water; therefore, those additives that can change the analyte mobility through electrostatic or donor^acceptor interactions should be fur- ther explored. z1998 Elsevier Science B.V. All rights reserved. Keywords: Nonaqueous capillary electrophoresis; Solvent effect; Cohesion energy density; Dielectric constant; Electron donor^acceptor interaction 1. Introduction Even though Walbroehl and Jorgenson [ 1 ] proved that capillary electrophoresis ( CE ) was not limited to aqueous solutions by demonstrating separations in acetonitrile-based buffers in 1984, it is only recently, with the realization that nonaqueous solvents allow CE to be applied to a much wider range of analytes, that interest in solvents other than water has been renewed. Recent publications have described separa- tions of organic [ 2,3 ] and inorganic ions [ 4 ], peptides [ 5 ], pharmaceuticals [ 6^9 ], polyethers [ 10 ], surfac- tants [ 11,12 ], porphyrin monomers [ 13 ] and por- phyrin oligomers [ 14 ]. Several papers have been pub- lished to describe the physical properties of nonaqueous solvents and how they can be utilized to improve separations in nonaqueous CE [ 15^17 ]. Although the potential of nonaqueous solvents in CE has been discussed, little attention has been paid to ¢nding more appropriate additives for nonaqueous systems. Part of the reason for the limited efforts in this area is that the additives commonly used in aqueous systems, such as surfactants and cyclodextrins, are often not as effective in nonaqueous solvents as they are in water. This article reviews recent developments in non- aqueous CE, focusing on the effects of the solvent on the strength of different types of analyte^additive 0165-9936/98/$ ^ see front matter ß 1998 Elsevier Science B.V. All rights reserved. PIIS0165-9936(98)00032-6 *Corresponding author. Tel.: +1 (604) 822 0878; Fax: +1 (604) 822 2847. E-mail: chen@chem.ubc.ca 424 trends in analytical chemistry, vol. 17, no. 7, 1998