Measurement of Physiological pH in Biological Specimens

描述（由申请人提供）：拟议研究的目标是(1)消除生理样品（如血浆）pH标准化的各种经验惯例的离子强度限制，并证明使用标准缓冲液中氯离子所需的单离子活度系数来分配pH值的Pitzer离子相互作用理论方法的合理性，离子强度I = 0.16 m，类似于在血清中发现的；(2)采用Pitzer配方对建立自洽pH标度有重要作用；(3)在有限离子强度（与I = 0.0 m相反）的“真实”条件下，使用具有和不具有液体结的电化学电池进行电动势测量的解离平衡实验研究。长期目标是大大改善不确定度小于或等于0.002的主要参考标准的pH测量状态。以等渗盐水为简单基质，在初始阶段选择了8种新的生物体系进行研究：(t) MOBS (0.04 m), NaMOBSate (0.04 m)；(2) TABS (0.04 m), NaTABSate (0.04 m), (3) HEPBS (0.04 m), NaHEPBSate (0.04 m)；(4) CABS (0.04 m), nacabate (0.04 m)；与0.05 m缓冲液成分相似。在临床化学中广泛使用这些数据是至关重要的。该项目的具体目标包括：(i)确定MOBS、TABS、HEPBS和CABS在5至55℃（包括37℃（体温））下的热力学解离常数，因为文献中没有这些重要生物缓冲液的数据；（ii）计算8种有用的标准参考溶液（每种缓冲液两种）在5至55摄氏度温度下离子强度与生理液体相似的pH值。例如，溶液的组成为：(a) 0.04 m MOBS + 0.04 m NaMOBSate + 0.12 m NaCI；(b) 0.05 m MOBS + 0.05 m NaMOBSate + 0.1t m NaCI；（iii）通过使用高度可重复的流动结电池来最小化液体结电位的误差，从而可以确定操作pH值；（iv）研究盐水介质中NaCI对调节体液中氢离子的基本离子过程的定量影响；(v)根据Pitzer惯例估计可靠pH值所需的单离子活度系数。

DESCRIPTION (provided by applicant): The goal of the proposed research is (1) the removal of the ionic strength restriction of the various empirical conventions for pH standardization of physiological samples such as plasma, and the justification of the Pitzer ion interaction theory approach to assignment of pH values using the required single ion activity coefficients of the chloride ion in the standard buffers, at an ionic strength I = 0.16 m, similar to that found in serum; (2) adoption of the Pitzer formulation will play an important role for the establishment of a self consistent pH scale; and (3) experimental studies of dissociation equilibria under the "real" conditions at finite ionic strength (as opposed to I = 0.0 m) using electro-chemical cells with and without liquid junction for electromotive-force measurements. The long-term goal is to greatly improve the state of pH measurements for primary reference standards with uncertainties less than or equal too .002. Utilizing isotonic saline as a simple matrix, eight new biological systems are chosen for study in the initial stages: (t) MOBS (0.04 m), NaMOBSate (0.04 m); (2) TABS (0.04 m), NaTABSate (0.04 m), (3) HEPBS (0.04 m), NaHEPBSate (0.04 m); and (4) CABS (0.04 m), NaCABSate (0.04 m); and similarly with 0.05 m buffer compositions. It is fundamental to have these data available for wide use in clinical chemistry. The specific aim of the project involves (i) to determine the thermodynamic dissociation constants of MOBS, TABS, HEPBS, and CABS at 5 to 55 degreesC, including 37 degrees C (body temperature), since no data are available in the literature for these important biological buffers; (ii) to calculate pH values for eight useful standard reference solutions (two from each buffer) at ionic strengths similar to those in physiological fluids at temperatures from 5 to 55xC. For example, the solutions have the compositions: (a) 0.04 m MOBS + 0.04 m NaMOBSate + 0.12 m NaCI; and (b) 0.05 m MOBS + 0.05 m NaMOBSate + 0.1t m NaCI; (iii) to minimize the errors from liquid junction potentials by using a highly reproducible flowing junction cell, so that the operational pH values can be ascertained, (iv) to study the quantitative effect of NaCI in saline media on the essential ionic processes which regulate hydrogen ion in body fluids, and (v) to estimate the single ion activity coefficients, based on the Pitzer convention, required for reliable pH values.