Critical evaluation of spectral information of benchtop vs. portable near-infrared spectrometers: quantum chemistry and two-dimensional correlation spectroscopy for a better understanding of PLS regression models of the rosmarinic acid content in Rosmarini folium

The Analyst ◽  
2017 ◽  
Vol 142 (3) ◽  
pp. 455-464 ◽  
Author(s):  
Christian G. Kirchler ◽  
Cornelia K. Pezzei ◽  
Krzysztof B. Beć ◽  
Sophia Mayr ◽  
Mika Ishigaki ◽  
...  
Keyword(s):  
Quantum Chemistry ◽  
Acid Content ◽  
Rosmarinic Acid ◽  
Regression Models ◽  
Near Infrared ◽  
Critical Evaluation ◽  
Correlation Spectroscopy ◽  
Spectral Information ◽  
Pls Regression ◽  
Two Dimensional

We show the importance of monitoring the performances of available NIR-spectrometers in every analytical area.

Aging of polypropylene probed by near infrared spectroscopy

2021 ◽  
pp. 096703352199911
Author(s):  
Hideyuki Shinzawa ◽  
Ryota Watanabe ◽  
Shogo Yamane ◽  
Maito Koga ◽  
Hideaki Hagihara ◽  
...  
Keyword(s):  
Regression Models ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Aging Treatment ◽  
Pls Regression ◽  
Two Dimensional ◽  
Compositional Change ◽  
Working Mechanism ◽  
Thermally Induced ◽  
Amorphous Structures

This paper describes the first in-depth attempt to characterize thermally induced aging of polypropylene (PP) samples by near infrared (NIR) spectroscopy. Significant levels of variation in NIR bands associated with short (amorphous-dominated) and long (crystalline-dominated) helices was readily captured when PP samples were subjected to thermal aging treatment. Partial least squares (PLS) regression models derived from the NIR spectra indicated significant level of correlation between the actual and predicted elongations of the samples. Analysis of PLS scores and two-dimensional (2 D) correlation spectra derived from the aged PP samples revealed inner working mechanism of the regression model. Namely, the aging treatment essentially induces compositional change in crystalline and amorphous structures of the PP samples, which eventually affect the variation of the PLS scores. Thus, by utilizing the scores, it becomes possible to predict the change in the elongation property of the aged PP sample.

scholarly journals Two-Dimensional Near-Infrared Correlation Spectroscopy Study of Ovalbumin in Acidic pH Region

2001 ◽  
Vol 41 (supplement) ◽  
pp. S44
Author(s):  
K. Murayama ◽  
T. Negawa ◽  
T. Hayashi ◽  
K. Kuwata ◽  
S. Era ◽  
...  
Keyword(s):  
Near Infrared ◽  
Correlation Spectroscopy ◽  
Acidic Ph ◽  
Two Dimensional ◽  
Spectroscopy Study

Structural Characterization of β-Lactoglobulin in Solution Using Two-Dimensional FT Mid-Infrared and FT Near-Infrared Correlation Spectroscopy

1997 ◽  
Vol 51 (4) ◽  
pp. 536-540 ◽  
Author(s):  
Nelson L. Sefara ◽  
Noel P. Magtoto ◽  
Hugh H. Richardson
Keyword(s):  
Near Infrared ◽  
Spectral Response ◽  
Correlation Spectroscopy ◽  
Two Dimensional ◽  
Helical Structures ◽  
Β Sheets ◽  
Α Helix ◽  
Combination Bands ◽  
Β Lactoglobulin ◽  
Β Sheet

Two-dimensional (2D) FT-IR correlation analysis was applied to both the mid-IR (MIR) and near-IR (NIR) regions to investigate changes in the secondary structures of β-lactoglobulin in D2O (or H2O) solvent systems consisting of varying concentrations of bromoethanol. Mid-IR correlation spectra indicate that the amide I bands corresponding to different structures (i.e., α-helical structures at 1650 cm−1, aggregated β-strands at 1620 cm−1, and β-sheet at 1636 cm−1) exhibit apparently different spectral response towards varying concentrations of bromoethanol. We propose that the mechanism for the conversion of the β-sheet into α-helix occurs in terms of two parallel pathways, i.e., (1) β-sheets → aggregated β-strands →α-helix, and (2) β-sheets →α-helix. Although the amide B/amide II combination bands give no spectral features relating to the secondary structure, changes were found in the C–H combination bands that suggest an interaction between the solvent and the protein.

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