|
1I - Physicochemical properties (MOP/47) Temperature Dependence Estimation of Water Solubility and Kow for Organic Chemicals Using RP-HPLC. Finizio, Antonio1, Di Guardo, Antonio2, Villa, Sara1, 1 University of Milano Bicocca, Milano, Italy2 University of Insubria, Varese, Italy ABSTRACT- The knowledge of physical-chemical properties such as aqueous solubility (S) or n-octanol-water partition coefficient (Kow) of organic compounds is fundamental for understanding their environmental distribution. On this basis, factors that can influence such properties become very important particularly for modeling purposes. For instance, it has been well recognized that partitioning and transport of persistent contaminants are strongly related to different environmental scenarios as direct consequence of temperature dependence of physical-chemical properties. However, data on these properties at different temperatures are virtually lacking, even if there is a need of knowledge about temperature dependence of both parameters. Recently, it has been proposed to extend the application of RP-HPLC method in order to obtain S and Kow at different temperatures (5-35°C). As it has been pointed out, among all experimental methods RP-HPLC is the most rapid because it does not require any quantification of concentrations. A further advantage coming from the upgrading of RP-HPLC method, for modeling purposes, could be the possibility to obtain, for each chemical, S and Kow at different temperatures in an homogeneous system, then avoiding the variability due to the selection of the data among different literature sources. In this work we examine in more detail the possibility to use RP-HPLC for measuring S and Kow at different temperatures. A comparison between the van 't Hoff plots obtained by means of RP-HPLC and direct determinations is made. Furthermore, the capability of predicting DwH (enthalpy of solution) and DowH (enthalpy of octanol-water phase transfer) by RP-HPLC retention factors is examined and value and limitations of the method are discussed. Key words: log Kow, water solubility, temperature, Van 't Hoff plot |
