scholarly journals Discrimination of Adulterated Ginkgo Biloba Products Based on 2T2D Correlation Spectroscopy in UV-Vis Range

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 433
Author(s):  
Agata Walkowiak ◽  
Kacper Wnuk ◽  
Michał Cyrankiewicz ◽  
Bogumiła Kupcewicz
Keyword(s):  
Ginkgo Biloba ◽  
Leaf Extract ◽  
Economic Value ◽  
Radical Scavenging ◽  
Principal Component ◽  
Poor Quality ◽  
Correlation Spectroscopy ◽  
Food Supplements ◽  
Two Dimensional ◽  
Herbal Products

Ginkgo biloba is a popular medicinal plant widely used in numerous herbal products, including food supplements. Due to its popularity and growing economic value, G. biloba leaf extract has become the target of economically motivated adulterations. There are many reports about the poor quality of ginkgo products and their adulteration, mainly by adding flavonols, flavonol glycosides, or extracts from other plants. In this work, we developed an approach using two-trace two-dimensional correlation spectroscopy (2T2D COS) in UV-Vis range combined with multilinear principal component analysis (MPCA) to detect potential adulteration of twenty G. biloba food supplements. UV-Vis spectral data are obtained for 80% methanol and aqueous extracts in the range of 245–410 nm. Three series of two-dimensional correlation spectra were interpreted by visual inspection and using MPCA. The proposed relatively quick and straightforward approach successfully differentiated supplements adulterated with rutin or those lacking ginkgo leaf extract. Supporting information about adulteration was obtained from the difference between the DPPH radical scavenging capacity of both extracts and from chromatographic (HPLC-DAD) fingerprints of methanolic samples.

Two-Dimensional Infrared Spectroscopy and Principal Component Analysis Studies on a New Azobenzene Derivative Supramolecular System Based on Hydrogen Bonds

2003 ◽  
Vol 57 (8) ◽  
pp. 933-942 ◽  
Author(s):  
Yuqing Wu ◽  
Ya-Qiong Hao ◽  
Min Li ◽  
Chaowei Guo ◽  
Yukihiro Ozaki
Keyword(s):  
Principal Component Analysis ◽  
Hydrogen Bonds ◽  
Supramolecular Assembly ◽  
Principal Component ◽  
Correlation Spectroscopy ◽  
Supramolecular System ◽  
Two Dimensional ◽  
Temperature Dependent ◽  
2D Correlation Spectroscopy ◽  
2D Correlation Analysis

Infrared (IR) spectra of a supramolecular assembly with an azobenzene derivative and intermolecular hydrogen bonds have been measured in the temperature range from 30 to 200 °C to investigate heat-induced structural changes and thermal stability. Principal component analysis (PCA) and two kinds of two-dimensional (2D) correlation spectroscopy, variable–variable (VV) 2D and sample–sample (SS) 2D spectroscopy, have been employed to analyze the observed temperature-dependent spectral variations. The PCA and SS 2D correlation analyses have demonstrated that the complete decoupling of hydrogen bonds in the supramolecular assembly occurs between 110 and 115 °C, which is in good agreement with the results of a differential scanning calorimetry (DSC) study for the heating process. The PCA of the IR spectra in the region of 3600–3100 cm−1 has illustrated that there are at least four principal components for the different NH2 and CONH species in the present supramolecular system. The VV 2D correlation spectroscopy study has provided information about the structure and strength of hydrogen bonds of NH2 and CONH groups and their temperature-dependent variations. The different species of hydrogen-bonded NH2 and CONH groups in the supramolecular system can be clarified by the VV 2D correlation analysis. The VV 2D correlation analysis has also revealed the specific order of the temperature-induced changes in the hydrogen bonds of NH2 and CONH groups.

Mechanism of Thermal Phase Transition of a Ferroelectric Liquid Crystal with Monotropic Transition Temperature Studied by Infrared Spectroscopy Combined with Principal Component Analysis and Sample—Sample Two-Dimensional Correlation Spectroscopy

2005 ◽  
Vol 59 (5) ◽  
pp. 620-629 ◽  
Author(s):  
Jinggang Zhao ◽  
Kenji Tatani ◽  
Yukihiro Ozaki
Keyword(s):  
Phase Transition ◽  
Principal Component ◽  
Correlation Spectroscopy ◽  
Heating Process ◽  
Ferroelectric Liquid Crystal ◽  
Two Dimensional ◽  
Thermal Dynamics ◽  
Alkyl Chains ◽  
The Core ◽  
2D Correlation Spectroscopy

Infrared (IR) spectra of FLC-154 (FLC: ferroelectric liquid crystal) with monotropic phase transition under a nonalignment state with a sample layer thickness of 24.5 μm were measured for heating process from 55 to 90 °C and a cooling process from 90 to 55 °C in increments of 1 °C. The thermal dynamics of FLC-154 were investigated by use of IR spectroscopy combined with principal component analysis (PCA) and sample–sample two-dimensional (2D) correlation spectroscopy. During the cooling, the FLC-154 molecule passes through the monotropic smectic- C* (Sm- C*) phase, which is transformed from the Sm- A phase. The results from PCA suggest that during the heating process, the thermal dynamics of the alkyl chains, core moiety, and C=O groups are similar to each other. Furthermore, PCA and sample–sample 2D correlation spectroscopy indicate that the alkyl chains and C=O groups in the chiral and core moieties are responsible for the emergence of the Sm- C* phase. This conclusion is very important because the IR data have given more evident cause for the emergence of the Sm- C* phase than the theoretical models such as the molecular-statistical theory of ferroelectric ordering and the indigenous polarization theory. Moreover, it has been found that some of the trans conformations of the alkyl chains of FLC-154 change partly to the gauche conformation when the phase transition from the crystalline phase to the Sm- A phase occurs. It has also been found that the intermolecular interactions of the C=O group in the core moiety in the Sm- A phase are weaker than those in the crystalline phase and that the conformational change occurs on the C–O–C bonds in the core moiety upon going from the crystalline to the Sm- A phase.

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