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标题：Application of Quantitative Proton Nuclear Magnetic Resonance Spectroscopy for the Compositional Analysis of Short-Chain Fatty Acid Ethyl Ester Mixtures
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作者：Ronald P. D’Amelia ; Masashi W. Kimura ; William F. Nirode 等
期刊名称：World Journal of Chemical Education
印刷版ISSN：2375-1665
电子版ISSN：2375-1657
出版年度：2020
卷号：9
期号：1
页码：8-13
DOI：10.12691/wjce-9-1-2
出版社：Science and Education Publishing
摘要：Nuclear magnetic resonance spectroscopy (NMR) is a widely used, powerful, and perhaps one of the most important instrumental techniques to qualitatively determine the molecular structure of an analyte. Using proton NMR in quantitative applications, also known as qNMR, is, however, uncommon, particularly in quantifying analytes within a mixture. To increase exposure to both qualitative and quantitative aspects of NMR in an undergraduate chemistry laboratory curriculum, we have developed a straightforward qNMR experiment suitable for adaptation into analytical and instrumental chemistry courses. The objective of this experiment is to determine the weight percent composition of a binary mixture containing short-chain fatty acid ethyl esters. We report on the methodologies used to determine the weight percent composition of ethyl acetate (EtAc), ethyl propionate (EtPr), and ethyl butyrate (EtBu) with mixtures ranging from 0% to 100%. The results demonstrate a strong, linear correlation of the weight percent composition of a selected component in a binary mixture found using proton qNMR with the theoretical compositions calculated gravimetrically. The experiment demonstrates the quantitative utility of proton NMR and serves as an educational tool for the undergraduate chemical laboratory.
关键词：quantitative analysis; nuclear magnetic resonance; proton NMR; undergraduate laboratory experiment; hands-on learning; ethyl esters; ethyl ester mixtures