Substoichiometric NMR Analysis for Oxygen-containing Organic Compounds

本文提出了一种新的含氧有机化合物（000）的亚化学计量核磁共振分析方法。用溶剂萃取法研究了邻苯二甲酸二（2-乙基己基）酯（DEHP）、二甲基亚砜（DMSO）、聚乙二醇400二甲醚（PEG）和聚氧乙烯辛基苯基醚（TX 100）等OOC与铕（Eu（hfa）_3）或镨（Pr（hfa）_3）形成加合物的化学计量比和平衡。结果表明，Ln（hfa）_3与PEG的加合物组成为1：1，与DEHP、DMSO和TX 100的加合物组成为1：1和1：2，并测定了相应的加合物形成常数。通过~ 1H NMR平衡分析，得到了加合物的形成常数和OOC质子的化学位移。这些知识导致了SNMR的开发。通过测定合成溶液中的DMSO，证明了SNMR的有效性。将亚化学计量的Eu（hfa）_3加入到DMSO样品溶液中，用核磁共振法测定了甲基质子的化学位移。向样品溶液中加标已知量的DMSO后，测量化学位移，然后计算样品中DMSO的量。DMSO的mM水平可通过仅测量分析物的化学位移而无需任何校准曲线来确定。化学位移测量的重复性好，相对标准偏差为0.01%，测定值的精密度和准确度都很高。

A novel analytical method of substoichiometric nuclear magnetic resonance analysis (SNMR) for oxygen-containing organic compounds (000 has been proposed The present method is based on the adduct formation of a paramagnetic lanthanide (III) (Ln) chelate as a shift reagent with OOC. The stoichiometry and the equilibrium of the adduct formation of tris(hexafluoroacetylacetonato)-europium(III)(Eu(hfa)_3) or -praseodymium(III) (Pr(hfa)_3) with OOC such as di(2-ethylhexyl) phthalate (DEHP), dimethyl sufoxide (DMSO), poly(ethylene glycol 400) dimethyl ether (PEG), and polyoxyethylene(10) octylphenyl ether (TX100) were studied by the solvent extraction method. The composition of the adducts of Ln(hfa)_3 was found to be only 1:1 for PEG and 1:1 and 1:2 for DEHP, DMSO, and TX100, and the respective adduct formation constants were determined. From the equilibrium analysis by 'H NMR, the adduct formation constant and the chemical shift of OOC protons in the adduct were obtained. This knowledge led to develop SNMR for OOC. The validity of SNMR was demonstrated by the determination of DMSO in a synthetic solution. A substoichiometric amount of Eu(hfa)_3 was added to the sample solution of DMSO and the chemical shift of the methyl-protons was measured by NMR. After a known amount of DMSO was spiked to the sample solution, the chemical shift was measured, and then the amount of DMSO in the sample was calculated. The mM level of DMSO could be determined by only measuring the chemical shift for the analyte without any calibration curves. The repeatability of the chemical shift measurement was as good as 0.01% as relative standard deviation, and the precision and accuracy for the determined values were very high.