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Báo cáo y học: " Defining the buffering process by a triprotic acid without relying on stewart-electroneutrality considerations"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học quốc tế cung cấp cho các bạn kiến thức về ngành y đề tài:Defining the buffering process by a triprotic acid without relying on stewart-electroneutrality considerations | Nguyen et al. Theoretical Biology and Medical Modelling 2011 8 29 http www.tbiomed.eom content 8 1 29 THEORETICAL BIOLOGY AND MEDICAL MODELLING RESEARCH Open Access Defining the buffering process by a triprotic acid without relying on stewart-electroneutrality considerations Minhtri K Nguyen Liyo Kao and Ira Kurtz Correspondence mtnguyen@mednet.ucla.edu Division of Nephrology UCLA Los Angeles CA USA 2 BioMed Central Abstract Upon the addition of protons to an aqueous solution a component of the H load will be bound i.e. buffered. In an aqueous solution containing a triprotic acid H can be bound to three different states of the acid as well as to OH- ions that are derived from the auto-ionization of H2O. In quantifying the buffering process of a triprotic acid one must define the partitioning of H among the three states of the acid and also the OH- ions in solution in order to predict the equilibrium pH value. However previous quantitative approaches that model triprotic acid titration behaviour and used to predict the equilibrium pH rely on the mathematical convenience of electroneutrality charge balance considerations. This fact has caused confusion in the literature and has led to the assumption that charge balance electroneutrality is a causal factor in modulating proton buffering Stewart formulation . However as we have previously shown although charge balance can be used mathematically as a convenient tool in deriving various formulae electroneutrality per se is not a fundamental physicochemical parameter that is mechanistically involved in the underlying buffering and proton transfer reactions. The lack of distinction between a mathematical tool and a fundamental physicochemical parameter is in part a reason for the current debate regarding the Stewart formulation of acid-base analysis. We therefore posed the following question Is it possible to generate an equation that defines and predicts the buffering of a triprotic acid that is based only on H .