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Deviations from Beer's law in electronic absorption and circular dichroism: Detection for enantiomeric excess analysis

Tang, Qiaozhi and Zhao, Lu and Xie, Jingqian and Liu, Kai and Liu, Weiping and Zhou, Shanshan (2019) Deviations from Beer's law in electronic absorption and circular dichroism: Detection for enantiomeric excess analysis. Chirality, 31 (7). pp. 492-501. ISSN 0899-0042. https://resolver.caltech.edu/CaltechAUTHORS:20190528-082735516

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Abstract

The electronic absorption (UV) to circular dichroism (CD) signal ratio can be used for enantiomeric excess (ee) analysis within linear range. However, CD detection often requires a high sample concentration where deviations from Beer's law may occur. Individual enantiomers of four chiral compounds were separated from commercial racemates by semipreparative high‐performance liquid chromatography (HPLC) with chiral columns. They were used to trace possible deviations in both UV and CD detection on achiral HPLC with a photodiode array detector and a CD detector. The CD/UV ratios for samples with the same ee value decreased by up to 7.8 to 52% when the injection volume increased, indicating that the linear standard curve of ee versus CD/UV is only valid within a narrow range. To extend the sample amount to a wider range, a data‐processing method was developed based on two second‐order polynomial functions, which were constructed to fit the relationship between the intensities of the UV and CD signals for two enantiomers. Moreover, a more simplified method based on a third‐order polynomial function was established to calculate the ee values. The variations between the predicted and experimental ee values were within ±0.08 for both methods. To our knowledge, this is the first study that the deviations from Beer's law are considered in both UV and CD detection for ee analysis.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1002/chir.23072DOIArticle
ORCID:
AuthorORCID
Tang, Qiaozhi0000-0003-1350-848X
Liu, Kai0000-0002-2109-8196
Liu, Weiping0000-0002-1173-892X
Zhou, Shanshan0000-0002-0050-7739
Additional Information:© 2019 Wiley Periodicals, Inc. Version of Record online: 21 May 2019; Manuscript accepted: 08 April 2019; Manuscript revised: 28 March 2019; Manuscript received: 28 November 2018. Funding Information: National Natural Science Foundation of China. Grant Numbers: 213320102007, 21427815, 41877494. Natural Science Foundation of Zhejiang Province. Grant Number: LY18B070012.
Funders:
Funding AgencyGrant Number
National Natural Science Foundation of China213320102007
National Natural Science Foundation of China21427815
National Natural Science Foundation of China41877494
Natural Science Foundation of Zhejiang ProvinceLY18B070012
Subject Keywords:achiral HPLC; Beer's law; circular dichroism; dual detector; enantiomeric excess
Issue or Number:7
Record Number:CaltechAUTHORS:20190528-082735516
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190528-082735516
Official Citation:Tang, Q, Zhao, L, Xie, J, Liu, K, Liu, W, Zhou, S. Deviations from Beer's law in electronic absorption and circular dichroism: Detection for enantiomeric excess analysis. Chirality. 2019; 31: 492– 501. https://doi.org/10.1002/chir.23072
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95802
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:28 May 2019 16:25
Last Modified:03 Oct 2019 21:16

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