The NMR chemical shift pH measurement revisited: Analysis of error and modeling of a pH dependent reference
The NMR chemical shift pH measurement revisited: Analysis of error and modeling of a pH dependent reference
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DOI：
10.1002/mrm.1910360505
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发表时间：
1996-11-01
影响因子：
3.3
通讯作者：
Evelhoch, JL
中科院分区：
文献类型：
--
作者：
Ackerman, JJH;Soto, GE;Evelhoch, JL
对参考位移与pH无关的传统化学交换Henderson-Hasselbalch NMR pH模型应用了基于标准微分演算的误差传播处理，从该分析中可以很自然地看到：(i)推导出的pH值的误差最小值发生在pH和指示剂pK(A)相等的区域，（ii）指示剂物种的酸和碱形式的极限化学位移的动态范围或差异，为了扩展有用的pH范围和NMR pH测定方法的效用，开发了一个更通用的模型，其中内部参考物质也被认为具有pH依赖的化学位移。标准溶液pH滴定的数据拟合到两个模型中，并估计了通常观察到的可电离磷代谢物家族(ATP，无机磷酸盐，磷酸乙醇胺和磷酸胆碱)和异代谢产物2-脱氧葡萄糖-6-磷酸与磷酸肌酸（ATP的α -磷酸）或水作为P-31或H-1化学位移的内部参考物质以及外部参考物质。
A standard differential calculus-based propagation of error treatment is applied to the traditional chemical-exchange Henderson-Hasselbalch NMR pH model in which the reference shift is pH independent, It is seen naturally from this analysis that (i) the error minimum in derived pH occurs in the region where pH and indicator pK(a) are equal and that (ii) the dynamic range, or difference between the limiting chemical shifts of acid and base forms of indicator species, determines the insensitivity of the technique to propagation of errors, To extend the useful pH range and utility of NMR pH determination methodology, a more general model is developed in which the internal reference species is also considered as having a pH-dependent chemical shift, Data from standard solution pH titrations are fitted to both models and parameters are estimated for the normally observed family of ionizable phosphorus metabolites (ATP, inorganic phosphate, phosphoethanolamine and phosphocholine) and the xenometabolite 2-deoxyglucose-6-phosphate with either phosphocreatine, the alpha-phosphate of ATP, or H2O taken as the P-31 or H-1 chemical shift internal reference species as well as with an external reference.