ABSTRACT
A dynamic development of analytical techniques helps in creating better tools for the determination and separation of xenobiotics and unknown compounds. The acid–base character and ionization of compounds can be understood from the value of their dissociation constant, which provides the pH value at which the ionized and nonionized forms of these compounds are observed. The chapter describes the properties of the analytes in the context of the selection of a proper analytical method as well as the methods for the estimation of parameters using the high-performance liquid chromatography (HPLC) technique. It is well known that the retention of ionizable compounds in reversed-phase HPLC depends on the pH of the mobile phase. One of the most important properties of xenobiotics is their lipophilicity. As majority of the xenobiotics are ionizable compounds, the influence of pH on lipophilicity is very important.
