Measurement of Physiological pH in Biological Specimens

生物样本中生理pH值的测量

• 批准号: 6556000
• 负责人: Rabindra N Roy
• 金额: $ 13.2万
• 依托单位: DRURY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-02-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6556000
• 关键词: acidity /alkalinity; body fluids; chemical stability; chemical standardization; electrodes; high performance liquid chromatography; ionic strengths; ionization constant; mathematical model; measurement; method development; phosphates; phthalates; physiology; sulfur compounds; thermodynamics

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.

描述（申请人提供）：所提出的研究的目标是（1）去除用于生理样品（例如血浆）的pH标准化的各种经验惯例的离子强度限制，以及使用标准缓冲液中氯离子的所需单离子活度系数来指定pH值的Pitzer离子相互作用理论方法的合理性，在离子强度I = 0.16m时，与血清中的结果相似：（2）Pitzer公式的采用将对建立一个自洽的pH标度起重要作用;（3）有限离子强度下“真实的”条件下离解平衡的实验研究（相对于I = 0.0 m），使用具有和不具有液体接界的电化学电池进行电动势测量。长期目标是大大改善一级参比标准品的pH测量状态，其不确定度小于或等于0.002。利用等渗盐水作为简单的基质，在初始阶段选择了八种新的生物系统进行研究：（0.04 m），NaMOBSate（0.04 m）;（2）TABS（0.04 m），NaTABSate 04 m），（3）HEPBS（0.04 m），NaHEPBS Sate（0.04 m）;和（4）CABS（0.04 m），NaCABS Sate（0.04 m）;并且类似地使用0.05 m缓冲液组合物。这是至关重要的，有这些数据可广泛用于临床化学。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 ℃）的热力学解离常数（体温），因为文献中没有这些重要生物缓冲液的数据;（ii）计算八种有用的标准参考溶液的pH值（每种缓冲液中两个），离子强度与生理液体中的离子强度相似，温度为5 - 55 ℃。例如，溶液具有以下组成：（a）0.04 m MOBS + 0.04 m NaMOBS Sate + 0.12 m NaCl;和（B）0.05 m MOBS + 0.05 m NaMOBS Sate +0.1 m NaCl;（iii）通过使用高度可再现的流动接面电池来最小化来自液体接面电位的误差，使得可以确定操作pH值，（iv）研究NaCl在盐水介质中对调节体液中氢离子的基本离子过程的定量影响，以及（v）根据Pitzer惯例估计可靠pH值所需的单离子活度系数。