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Li K, Zhou F, He A, Guo R, Li X, Xu Y, Noda I, Ozaki Y, Wu J. Intensity Enhancement of a Two-Dimensional Asynchronous Spectrum Without Noise Level Fluctuation Escalation Using a One-Dimensional Spectra Sequence Change. APPLIED SPECTROSCOPY 2021; 75:422-433. [PMID: 33103490 DOI: 10.1177/0003702820971714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Previously, we demonstrated that the intensities of cross-peaks in a two-dimensional asynchronous spectrum could be enhanced using sequence change of the corresponding one-dimensional spectra. This unusual approach becomes useful when the determination of the sequential order of physicochemical events is not essential. However, it was not known whether the level of noise in the two-dimensional asynchronous spectrum was also escalated as the sequence of one-dimensional spectra changed. We first investigated the noise behavior in a two-dimensional asynchronous spectrum upon changing the sequence of the corresponding one-dimensional spectra on a model system. In the model system, bilinear data from a chromatographic-spectroscopic experiment on a mixture containing two components were analyzed using a two-dimensional asynchronous spectrum. The computer simulation results confirm that the cross-peak intensities in the resultant a two-dimensional asynchronous spectrum were indeed enhanced by more than 100 times as the sequence of one-dimensional spectra changed, whereas the fluctuation level of noise, reflected by the standard deviation of the value of a two-dimensional asynchronous spectrum at a given point, was almost invariant. Further analysis on the model system demonstrated that the special mathematical property of the Hilbert-Noda matrix (the modules of all column vectors of the Hilbert-Noda matrix being a near constant) accounts for the moderate variation of the noise level during the changes of the sequence of one-dimensional spectra. Next, a realistic example from a thermogravimetry-Fourier transform infrared spectroscopy experiment with added artificial noise in seven one-dimensional spectra was studied. As we altered the sequence of the seven FT-IR spectra, the variation of the cross-peak intensities covered four orders of magnitude in the two-dimensional asynchronous spectra. In contrast, the fluctuation of noise in the two-dimensional asynchronous spectra was within two times. The above results clearly demonstrate that a change in the sequence of one-dimensional spectra is an effective way to improve the signal-to-noise level of the two-dimensional asynchronous spectra.
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Affiliation(s)
- Kaili Li
- Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing, China
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, 12465Peking University, Beijing, China
| | - Fengshan Zhou
- Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing, China
| | - Anqi He
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, 12465Peking University, Beijing, China
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, China
| | - Ran Guo
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, 12465Peking University, Beijing, China
- Jiangsu JITRI Molecular Engineering Inst. Co., Ltd, Suzhou, China
| | - Xiaopei Li
- Instrumental Analysis Center, 12400Dalian Polytechnic University, Dalian, China
| | - Yizhuang Xu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, 12465Peking University, Beijing, China
- Jiangsu JITRI Molecular Engineering Inst. Co., Ltd, Suzhou, China
| | - Isao Noda
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, 12465Peking University, Beijing, China
- Department of Materials Science and Engineering, University of Delaware, Newark, DE, USA
| | - Yukihiro Ozaki
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, 12465Peking University, Beijing, China
- Department of Chemistry, School of Science and Technology, 12907Kwansei Gakuin University, Hyogo, Japan
| | - Jinguang Wu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, 12465Peking University, Beijing, China
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Ni L, Zhao J, Song H, Zhang Z, Feng J, Xu Y, Noda I. Application of two-dimensional correlation fluorescence spectroscopy to detect the presence of trace amount of substances. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 237:118374. [PMID: 32334325 DOI: 10.1016/j.saa.2020.118374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 04/10/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Although fluorescence spectroscopy is a highly sensitive method, it is still rather difficult to identify a minor fluorescent component whose fluorescent peak is overlapped and masked by a dominant fluorescent component in a sample solution. Herein, we describe a two-dimensional correlation spectroscopy (2D-COS) approach based on the Kasha's rule to solve the above common problem. We initially suppose that a sample solution contains the major component only, and the spectral behavior of the major component obeys the Kasha's rule. Then, the shapes of emission spectra obtained under excitation lights of different wavelengths remain invariant. Under this condition, the introduction of a minor fluorescent component can be reflected by the changes on the shapes of emission peaks in the series of emission spectra. Moreover, subtle changes, which are difficult to be found in the original spectra, can be clearly visualized as cross peaks in 2D asynchronous spectrum constructed using a series of emission spectra. In addition, we demonstrate that the intensities of cross peaks can be enhanced by changing the sequence of the series of emission spectra. We utilize the approach on an aqueous solution containing eosin Y and a trace amount of bromocresol green. The presence of bromocresol green with the concentration as low as 400 nM can be revealed via the cross peaks in the resultant 2D asynchronous spectra. In a preliminary study, we suggest that 2D disrelation spectrum might provide an alternative chance to reveal the presence of small amount bromocresol green.
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Affiliation(s)
- Lei Ni
- School of Life Science and Technology, University of Electronic Science and Technology, Chengdu, Sichuan 610054, PR China; Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China; Jiangsu JITRI Molecular Engineering Inst. Co., Ltd., Suzhou, Jiangsu 215500, PR China
| | - Jiaojiao Zhao
- School of Life Science and Technology, University of Electronic Science and Technology, Chengdu, Sichuan 610054, PR China
| | - Honghong Song
- School of Life Science and Technology, University of Electronic Science and Technology, Chengdu, Sichuan 610054, PR China; Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China
| | - Zhuoyue Zhang
- School of Life Science and Technology, University of Electronic Science and Technology, Chengdu, Sichuan 610054, PR China
| | - Juan Feng
- School of Life Science and Technology, University of Electronic Science and Technology, Chengdu, Sichuan 610054, PR China.
| | - Yizhuang Xu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China; Jiangsu JITRI Molecular Engineering Inst. Co., Ltd., Suzhou, Jiangsu 215500, PR China.
| | - Isao Noda
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, PR China; Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, United States
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Suzuki Y, Furuya H. Insights into the helix-sense inversion of poly(β-phenethyl-L-aspartate) by two-dimensional Raman correlation spectroscopy. J Pept Sci 2018; 24:e3079. [PMID: 29624787 DOI: 10.1002/psc.3079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 03/06/2018] [Accepted: 03/09/2018] [Indexed: 01/30/2023]
Abstract
In this study, the transition process of the helix-sense inversion of poly(β-phenethyl-L-aspartate) was investigated by Raman scattering and 2-dimensional correlation spectroscopy. Temperature-dependent Raman spectra were obtained during the helix-sense inversion. The results of 2-dimensional correlation analysis in the spectral regions of 1600-1800 and 3200-3400 cm-1 showed that the intensity changes of the side-chain ester C═O stretching bands occurred prior to those of amide A and amide I bands in the unwinding process of αR-helix on heating. The sequential order of the intensity changes for amide A, amide I, and the side-chain ester C═O stretching bands during the inversion process was determined. It was found that the conformation change of the side chain occurred prior to that of the main chain for the αR-helix on heating. Thus, we concluded that the transformation of the backbone chain from right-handed to left-handed is triggered by the conformational change of the side chains.
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Affiliation(s)
- Yuki Suzuki
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1-S1-20 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
| | - Hidemine Furuya
- School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-S1-20 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan
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