Application of Multivariate Methods to the Simultaneous Fourier Transform Infrared (FT-IR) Spectrometric Determination of Stereo-Isomers; Quinine and Quinidine

Wahbi, Abdel‐Aziz M.; Moneeb, Marwa S.; Hewala, Ismail I.; Bahnasy, Mahmoud Farouk

doi:10.1248/cpb.56.787

Cited by 5 publications

(2 citation statements)

References 8 publications

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“…Some vibrational spectra of cinchona alkaloids have already been reported for the solid state as well as different solvents . Recently, we have published FT‐Raman spectra of cinchona alkaloids in the fingerprint region .…”

Section: Resultsmentioning

confidence: 99%

Vibrational analysis of cinchona alkaloids in the solid state and aqueous solutions

Roman

Chruszcz‐Lipska

Barańska

2015

J Raman Spectroscopy

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Cinchona alkaloids are well-known antimalarial compounds also used in asymmetric synthesis in organic chemistry. In this work, vibrational spectra of quinine, quinidine, cinchonine, and cinchonidine were acquired and interpreted on the basis of theoretical calculations. Normal Raman spectra of the alkaloids in solution exhibit similar patterns and cannot be used for differentiation between the derivatives (e.g. quinine and cinchonidine) and corresponding pseudoenantiomers (e.g. quinine and quinidine). Thus, Raman Optical Activity (ROA) method was applied to show distinct differences related to the configuration of chiral atoms. ROA allowed unequivocal identification of the pseudoenantiomers based on the sign of the characteristic bands from a single measurement. The experiments were supported by the theoretical approach including conformational study followed by wavenumber calculations and Potential Energy Distribution (PED) analysis. For quinine, vibrational spectroscopy was additionally used to show its structural changes in aqueous solutions at various pH and its distribution in a pharmaceutical product. Spatial distribution of quinine in a drug was observed by the FT-Raman mapping technique.

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Section: Resultsmentioning

confidence: 99%

Vibrational analysis of cinchona alkaloids in the solid state and aqueous solutions

Roman

Chruszcz‐Lipska

Barańska

2015

J Raman Spectroscopy

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“…[42, 43, 44] Malinowski’s F -test and cross validation have been compared in the past, yielding mixed results. [26, 45, 46, 47] Here, cross validation was not able to estimate rank for all data sets because the rank of many training sets (as in Table 1) was ambiguous using this approach.…”

Section: Resultsmentioning

confidence: 99%

Rank Estimation and the Multivariate Analysis of in Vivo Fast-Scan Cyclic Voltammetric Data

2010

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Principal component regression has been used in the past to separate current contributions from different neuromodulators measured with in vivo fast-scan cyclic voltammetry. Traditionally, a percent cumulative variance approach has been used to determine the rank of the training set voltammetric matrix during model development, however this approach suffers from several disadvantages including the use of arbitrary percentages and the requirement of extreme precision of training sets. Here we propose that Malinowski's F-test, a method based on a statistical analysis of the variance contained within the training set, can be used to improve factor selection for the analysis of in vivo fast-scan cyclic voltammetric data. These two methods of rank estimation were compared at all steps in the calibration protocol including the number of principal components retained, overall noise levels, model validation as determined using a residual analysis procedure, and predicted concentration information. By analyzing 119 training sets from two different laboratories amassed over several years, we were able to gain insight into the heterogeneity of in vivo fast-scan cyclic voltammetric data and study how differences in factor selection propagate throughout the entire principal component regression analysis procedure. Visualizing cyclic voltammetric representations of the data contained in the retained and discarded principal components showed that using Malinowski's F-test for rank estimation of in vivo training sets allowed for noise to be more accurately removed. Malinowski's F-test also improved the robustness of our criterion for judging multivariate model validity, even though signal-to-noise ratios of the data varied. In addition, pH change was the majority noise carrier of in vivo training sets while dopamine prediction was more sensitive to noise.

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Chapter 4 Determination of Alkaloids through Infrared and Raman Spectroscopy

Barańska

Schulz

2009

The Alkaloids: Chemistry and Biology

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Application of Multivariate Methods to the Simultaneous Fourier Transform Infrared (FT-IR) Spectrometric Determination of Stereo-Isomers; Quinine and Quinidine

Cited by 5 publications

References 8 publications

Vibrational analysis of cinchona alkaloids in the solid state and aqueous solutions

Vibrational analysis of cinchona alkaloids in the solid state and aqueous solutions

Rank Estimation and the Multivariate Analysis of in Vivo Fast-Scan Cyclic Voltammetric Data

Chapter 4 Determination of Alkaloids through Infrared and Raman Spectroscopy

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