The Theory of Buffer Action

Section 19.1 discusses the Brpnsted theory of acids and bases, which extends the concepts of add and base beyond aqueous solutions and also explains the acidic or basic nature of solutions of most salts. Dissociation constants, the equilibrium constants for the reactions of weak acids or bases with water, are introduced in Section 19.2. The concept of the ionization of covalent compounds is extended to water itself in Section 19.3, which also covers pH, a scale of acidity and basicity. Section 19.4 describes buffer solutions, which resist change in their acidity or basicity even when some strong acid or base is added. Both the preparation and the action of buffer solutions are explained. Section 19.5 discusses the equilibria of acids containing more than one ionizable hydrogen atom per molecule. 

Capillary zone electrophoresis (CZE) is the most commonly used separation mode in CE microchip due to its versatility, ease of operation, and separation power. This electrophoretic mode is based on the theory and mechanism of action directly transferred from the conventional CE. In CZE the channel contains only a buffered medium and the electrophoretic mobilities of the analytes depend on their charge/mass ratio, acting as separation mechanism. These different velocities make possible to separate cations and anions if the EOF is strong, in order to lead anionic substances to the detector located usually at the cathode. It has the limitation of being useful only for separation of charged species. 

General theory devoted to calculation of pH and distribution of species in particular buffer mixtures can be foimd in [20, 67-70]. Chemical formirlation includes a number of the mass-action equations linked with the mass and charge conservation equations. Limiting or extended forms of the Debye-Hiickel expressions for activity... 

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