Measurement of Physiological pH in Biological Specimens

现今常用的pH值标度是为了精确计算酸度函数的差值而设计的 参考标准品和其他性质相当但酸度不同的介质之间的差异。这些 标准品是稀释的缓冲溶液，其离子强度通常接近0.1 m;即， 比生理上感兴趣的大多数介质（I = 0.16 m）更高。对其他解决方案结果的可靠解释 可以预期具有可比组成的，但是其他的，例如含有更高量的 中性盐可能是可疑。尽管涵盖大多数生理介质的pH范围的标准是 但是，由于现有技术，目前很难选择与其他参考溶液密切匹配的参考溶液。 关注未知介质的属性。 对于I = 0.1 m以上的离子强度，每个人都是“自己”，结果的差异（计算 单离子活度系数）之间的差异。一个长期的目标， 研究的目的是消除目前各种公约的限制（贝茨-古根海姆，有效期至I = 0.1 m）通过使用Pitzer离子相互作用方法，以（i）计算单个离子的所需单离子活性， 在离子强度I = 0.16 m时测定标准缓冲液pH值时的离子种类，类似 生物样本（血液、血浆等）中发现的;（二）将其与基于 更简单的公约;和（iii）评估在生理介质（I = 0.16米）的变化产生的影响 标准品或目标介质的中性盐含量。如果成功， 标准参比溶液的pH值应与生理介质的性质密切匹配， 可能的，随之而来的是这些实验pH值数据的可靠性和意义的改善， 媒体在这方面，十二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，这可能 建立一个自洽的，统一的pH值标度，适用于所有情况（不同的离子强度，混合物， 等）。因此，皮策公约和提法符合要求。 在过去，大约600名学生（现有补助金约70名学生）受到了挑战， 这个机会，许多人已经朝着科学和医学的职业生涯的动机。根据该结果 计划，这个机会将提供给学生再次工作，更综合，重点突出， 有价值的研究计划

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 = 0.16m) 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.