Quantitative vibrational spectroscopy on liquid mixtures: concentration units matter

Manen, Henk‐Jan van; Gerretzen, Jan; Smout, Martijn; Postma, G.J.; Jansen, Jeroen J.

doi:10.1039/d1an00151e

Cited by 6 publications

(3 citation statements)

References 20 publications

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“…The resulting spectrum is intended to mimic a physical mixture, in which intermolecular AI–polymer interactions are absent. The use of volume-based concentration units for quantitative vibrational spectroscopy has been experimentally approved . This can also be rationalized with reference to the law of additivity of absorptions corresponding to two noninteracting solutes dissolved in an absorption-inactive solvent, based on Lambert–Beer’s law as A mix false( ν false) = ε 1 false( ν false) c 1 b + ε 2 false( ν false) c 2 b Here, A mix stands for the absorbance of the mixture, ε is the mass absorptivity of the corresponding solute in the solution (L g –1 cm –1 ), c represents the mass concentration (g L –1 ) of the corresponding solute in the solution, and b denotes the path length of the light.…”

Section: Resultsmentioning

confidence: 99%

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Molecular Dynamics and Diffusion in Amorphous Solid Dispersions Containing Imidacloprid

et al. 2023

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The main goal of this study is to develop an experimental toolbox to estimate the self-diffusion coefficient of active ingredients (AI) in single-phase amorphous solid dispersions (ASD) close to the glass transition of the mixture using dielectric spectroscopy (DS) and oscillatory rheology. The proposed methodology is tested for a model system containing the insecticide imidacloprid (IMI) and the copolymer copovidone (PVP/VA) prepared via hot-melt extrusion. For this purpose, reorientational and the viscoelastic structural (α-)relaxation time constants of hot-melt-extruded ASDs were obtained via DS and shear rheology, respectively. These were then utilized to extract the viscosity as well as the fragility index of the dispersions as input parameters to the fractional Stokes−Einstein (F-SE) relation. Furthermore, a modified version of Almond−West (AW) formalism, originally developed to describe charge diffusion in ionic conductors, was exercised on the present model system for the estimation of the AI diffusion coefficients based on shear modulus relaxation times. Our results revealed that, at the calorimetric glass-transition temperature (T g ), the self-diffusion coefficients of the AI in the compositional range from infinite dilution up to 60 wt % IMI content lied in the narrow range of 10 −18 − 10 −20 m 2 s −1 , while the viscosity values of the dispersions at T g varied between 10 8 Pa s and 10 10 Pa s. In addition, the phase diagram of the IMI-PVP/VA system was determined using the melting point depression method via differential scanning calorimetry (DSC), while mid-infrared (IR) spectroscopy was employed to investigate the intermolecular interactions within the solid dispersions. In this respect, the findings of a modest variation in melting point at different compositions stayed in agreement with the observations of weak hydrogen bonding interactions between the AI and the polymer. Moreover, IR spectroscopy showed the intermolecular IMI-IMI hydrogen bonding to have been considerably suppressed, as a result of the spatial separation of the AI molecules within the ASDs. In summary, this study provides experimental approaches to study diffusivity in ASDs using DS and oscillatory rheology, in addition to contributing to an enhanced understanding of the interactions and phase behavior in these systems.

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Section: Resultsmentioning

confidence: 99%

“…The use of volume-based concentration units for quantitative vibrational spectroscopy has been experimentally approved. 77 This can also be rationalized with reference to the law of additivity of absorptions corresponding to two noninteracting solutes dissolved in an absorption-inactive solvent, based on Lambert−Beer's law as 78…”

Section: ■ Methodsmentioning

confidence: 99%

Molecular Dynamics and Diffusion in Amorphous Solid Dispersions Containing Imidacloprid

et al. 2023

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“…The Raman intensity is linearly related to the volume-based concentration . Raman intensity is proportional to the volume of the S 0 globule.…”

Section: Resultsmentioning

confidence: 99%

Dynamically Quantifying Intracellular Elemental Sulfur and Predicting Pertinent Gene Transcription by Raman Spectroscopy in Living Cells

Wang

et al. 2023

Anal. Chem.

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The ability to monitor changes in metabolites and corresponding gene transcription within living cells is highly desirable. However, most current assays for quantification of metabolites or for gene transcription are destructive, precluding tracking the real-time dynamics of living cells. Here, we used the intracellular elemental sulfur in a Thiophaeococcus mangrovi cell as a proof-of-concept to link the quantity of metabolites and relevant gene transcription in living cells by a nondestructive Raman approach. Raman spectroscopy was utilized to quantify intracellular elemental sulfur noninvasively, and a computational mRR (mRNA and Raman) model was developed to infer the transcription of genes relevant to elemental sulfur. The results showed a significant linear correlation between the exponentially transformed Raman spectral intensity of intracellular elemental sulfur and the mRNA levels of genes encoding sulfur globule proteins in T. mangrovi. The mRR model was verified independently in two genera of Thiocapsa and Thiorhodococcus, and the mRNA levels predicted by mRR showed high consistency with actual gene expression detected by real-time polymerase chain reaction (PCR). This approach could enable noninvasive assessment of the quantity of metabolites and link the pertinent gene expression profiles in living cells, providing useful baseline data to spectroscopically map various omics in real time.

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Molecular level interpretation of excess infrared spectroscopy

Śmiechowski

2021

Journal of Molecular Liquids

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Quantitative vibrational spectroscopy on liquid mixtures: concentration units matter

Abstract: Quantitative vibrational absorption spectroscopies rely on Beer’s law relating spectroscopic intensities in a linear fashion to chemical concentrations. To address and clarify contrasting results in the literature about the difference...

Cited by 6 publications

References 20 publications

Molecular Dynamics and Diffusion in Amorphous Solid Dispersions Containing Imidacloprid

Molecular Dynamics and Diffusion in Amorphous Solid Dispersions Containing Imidacloprid

Dynamically Quantifying Intracellular Elemental Sulfur and Predicting Pertinent Gene Transcription by Raman Spectroscopy in Living Cells

Molecular level interpretation of excess infrared spectroscopy

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