ELECTROCHEMICALLY MODULATED LIQUID-CHROMATOGRAPHY (EMLC) AS A PROBE OF THE ADSORPTION CHARACTERISTICS OF MONOSUBSTITUTED BENZENES AT POROUSGRAPHITIC CARBON

The utility of electrochemically modulated liquid chromatography (EMLC ) as a probe of the adsorption characteristics of monosubstituted benz enes at porous graphitic carbon (PGC) is investigated. An analysis on the extent of the changes in retention as a function of applied potent ial (E-appl) is performed to develop preliminary insights into the cri tical interactions between these compounds and PGC. The results show t hat the retention, and therefore the extent of adsorption, of these co mpounds increases as E-appl becomes more positive. Furthermore, the de pendence of the increase varies between compounds, reflecting differen ces in the sensitivities of the adsorption strengths to pi-donor/accep tor interactions. Together, these results demonstrate the potential va lue of EMLC as (1) a tool for investigating fundamental issues related to the adsorption of organic compounds on electrode surfaces and (2) a separation technique for mixtures of this important class of analyte s. (C) 1998 Elsevier Science S.A. All rights reserved.