Measurement of Physiological pH in Biological Specimens

生物样本中生理pH值的测量

• 批准号: 7127750
• 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 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7127750
• 关键词: acid base balance; acidity /alkalinity; analytical chemistry; biotechnology; buffers; chemical standardization; electrochemistry; growth media; ionic strengths; sodium chloride

DESCRIPTION (provided by applicant): The scale of pH in common use today is designed to yield accurate differences of an acidity function between a standard of reference and other media of a comparable nature but differing acidity. These standards are dilute buffer solutions with typically ionic strengths near 0.1 m; that is, considerably more dilute than most media (I = 0.16 m) of physiological interest. Reliable interpretation of the results for other solutions of comparable composition can be expected, but others, such as those containing higher quantities of neutral salt may be suspect. Although standards covering the range of pH of most physiological media are available, it is presently difficult to choose a reference solution that matches closely in respect to other properties of the unknown media of concern. For ionic strength above I = 0.1 m, everyone is 'on his own' and differences of the results (calculation of the single ion activity coefficient) between various laboratories are likely to occur. A long-term goal of the research is to remove the present restriction of various conventions (the Bates-Guggenheim, valid up to I = 0.1 m) by use of the Pitzer ion-interaction approach to (i) calculate the required single ion activity of a single ionic species in the determination of pH values for the standard buffers at an ionic strength I = 0.16 m, similar to that found in biological specimens (blood, plasma, etc.); to (ii) compare them with those based on the simpler conventions; and to (iii) evaluate the effect produced in physiological media (I = 0.16 m) by variations in the neutral salt content of either the standard or the medium of interest. If successful, the assignment of pH values to standard reference solutions matching closely the properties of physiological media should be possible, with a consequent improvement in the reliability and meaning of experimental pH data for these media. In this connection, twelve new biochemical buffer compounds (HEPPS, AMPSO, HEPPSO, PIPESO, CAPS, CAPSO, MOPSO, ACES, CHES, MES, TRICINE, and PIPES) will be investigated. Finally, this may establish a self-consistent, unified pH scale that is applicable to all cases (different ionic strengths, mixtures, etc.). Thus, the Pitzer convention and formulation fit the bills. In the past, some 600 students (about seventy students for the existing grant) have been challenged by this opportunity and many have been motivated toward careers in science and medicine. Consequently, it is planned that this opportunity will be offered to students once more to work on a more integrated, focused, and meritorious research proposal.

描述（由申请人提供）：目前常用的pH值标度旨在产生参比标准品和其他性质相当但酸度不同的介质之间酸度函数的准确差异。这些标准品是稀释的缓冲溶液，通常离子强度接近0.1 m;即比大多数生理学感兴趣的介质（I = 0.16 m）稀释得多。可以预期对具有可比组成的其他溶液的结果进行可靠的解释，但其他溶液（例如含有更高量中性盐的溶液）的结果可能可疑。尽管可获得涵盖大多数生理介质的pH范围的标准品，但目前难以选择与所关注的未知介质的其他性质密切匹配的参比溶液。对于I = 0.1 m以上的离子强度，每个人都是“自己”，不同实验室之间的结果（单离子活度系数的计算）可能会出现差异。研究的一个长期目标是消除目前各种惯例的限制（Bates-Guggenheim，有效值高达I = 0.1 m），通过使用Pitzer离子相互作用方法，（i）计算在离子强度I = 0.16 m下测定标准缓冲液pH值时单个离子物质所需的单离子活度，与生物样本（血液、血浆等）中发现的相似;（ii）将它们与基于更简单的惯例的那些进行比较;以及（iii）通过标准品或感兴趣的介质的中性盐含量的变化来评估在生理介质（I = 0.16 m）中产生的影响。如果成功的话，将pH值分配给与生理介质的特性密切匹配的标准参比溶液应该是可能的，从而提高这些介质的实验pH值数据的可靠性和意义。在这方面，将研究12种新的生化缓冲化合物（HEPPS、AMPSO、HEPPSO、PIPESO、CAPS、CAPSO、MOPSO、ACES、CHES、MES、TRICINE和PIPES）。最后，这可以建立适用于所有情况（不同离子强度、混合物等）的自洽、统一的pH标度。因此，皮策公约和提法符合要求。在过去，约600名学生（约70名学生现有的补助金）已经受到这个机会的挑战，许多人已经对科学和医学的职业生涯的动机。因此，计划将再次为学生提供这个机会，以制定更综合，更集中和更有价值的研究计划。