Comparison of Raman and attenuated total reflectance (ATR) infrared spectroscopy for water quantification in natural deep eutectic solvent

Elderderi, Suha; Wils, Laura; Leman-Loubière, Charlotte; Henry, Sandra; Byrne, Hugh J.; Chourpa, Igor; Munnier, Emilie; Elbashir, Abdalla A.; Boudesocque-Delaye, Leslie; Bonnier, Franck

doi:10.1007/s00216-021-03432-2

Cited by 15 publications

(19 citation statements)

References 78 publications

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“…As for ATR-IR, the Raman-B spectrum of H 2 O exhibits a single weak feature at ~1640 cm −1 (scissoring bending) and broad OH symmetric and asymmetric stretching modes with two maxima at ~3200 cm −1 and ~3400 cm −1 [ 82 , 83 ] ( Figure 8 and Figure 9 A(b),B(b)). The bands observed are in agreement with previous investigations conducted on glycerol-based NADES using a Raman microscope [ 65 ] and later using a Raman handheld system [ 66 ]. In Figure 8 , it is seen that, in the high wavenumber region, variations corresponding to water features can be observed, while in the fingerprint region the strong features from the LALP NADES constituents at ~1480 and ~1700 cm −1 obscure the weaker H 2 O scissoring bending.…”

Section: Resultssupporting

confidence: 91%

“…Consistent with previous studies by Elderderi et al [ 65 , 66 ], raw Raman spectra did not deliver the optimal outcome for Raman-B; therefore, for the purpose of this study aiming at illustrating the best achievable quantitative performance, a pre-processing protocol has been applied.…”

Section: Methodssupporting

confidence: 56%

“…Water quantification, or moisture analysis, using vibrational spectroscopy has been reported in the literature for MIRS in lubricants [ 48 , 49 ] or milk [ 50 ]; for RS in trace water quantification in glass [ 51 , 52 ] and recently for moisture content determination in flour or pasta samples [ 53 , 54 ]; and for NIRS in food [ 55 ] as a PAT (process analytical technology) tool for moisture content determination during freeze-drying processes [ 56 , 57 ], in lubricants [ 49 ], organic solvents [ 58 ] or absolute water content of minerals [ 59 ], water content in skin [ 60 , 61 , 62 ] and pharmaceutical pellets [ 63 ]. Recently, Elderderi et al reported the first demonstrations of attenuated total reflectance MIRS (ATR-IR) [ 64 ] and RS [ 65 , 66 ] for water quantification using glycerol-based NADES as models, i.e., Betaine:Glycerol (1:8, mol/mol), Choline Chloride:Glycerol (1:2, mol/mol) and Glucose:Glycerol (1:3, mol/mol), each with systematically varying added water concentrations in the range of 0% w / w to 40% w / w .…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Vibrational Spectroscopic Techniques for Quantification of Water in Natural Deep Eutectic Solvents

et al. 2022

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Vibrational spectroscopic techniques, i.e., attenuated total reflectance infrared (ATR-IR), near infrared spectroscopy (NIRS) and Raman spectroscopy (RS), coupled with Partial Least Squares Regression (PLSR), were evaluated as cost-effective label-free and reagent-free tools to monitor water content in Levulinic Acid/L-Proline (LALP) (2:1, mol/mol) Natural Deep Eutectic Solvent (NADES). ATR-IR delivered the best outcome of Root Mean Squared Error (RMSE) of Cross-Validation (CV) = 0.27% added water concentration, RMSE of Prediction (P) = 0.27% added water concentration and mean % relative error = 2.59%. Two NIRS instruments (benchtop and handheld) were also compared during the study, respectively yielding RMSECV = 0.35% added water concentration, RMSEP = 0.56% added water concentration and mean % relative error = 5.13% added water concentration, and RMECV = 0.36% added water concentration, RMSEP = 0.68% added water concentration and mean % relative error = 6.23%. RS analysis performed in quartz cuvettes enabled accurate water quantification with RMECV = 0.43% added water concentration, RMSEP = 0.67% added water concentration and mean % relative error = 6.75%. While the vibrational spectroscopic techniques studied have shown high performance in relation to reliable determination of water concentration, their accuracy is most likely related to their sensitivity to detect the LALP compounds in the NADES. For instance, whereas ATR-IR spectra display strong features from water, Levulinic Acid and L-Proline that contribute to the PLSR predictive models constructed, NIRS and RS spectra are respectively dominated by either water or LALP compounds, representing partial molecular information and moderate accuracy compared to ATR-IR. However, while ATR-IR instruments are common in chemistry and physics laboratories, making the technique readily transferable to water quantification in NADES, Raman spectroscopy offers promising potential for future development for in situ, sample withdrawal-free analysis for high throughput and online monitoring.

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Section: Resultssupporting

confidence: 91%

Section: Methodssupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

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Comparison of Vibrational Spectroscopic Techniques for Quantification of Water in Natural Deep Eutectic Solvents

et al. 2022

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“…Although this work demonstrated the importance and efficiency of infrared analysis, water quantification was performed by depositing small volumes of NaDES on the infrared crystal, which requires a cleaning step between samples. Thus, in a complementary work carried out by the same team, the Raman technique was compared to the quantification of FTIR water [28]. Nowadays, Raman spectrum can be collected in situ directly from the sample container.…”

Section: Water Quantification: Karl Fischer (Kf) Titration and Vibrational Spectroscopymentioning

confidence: 99%

Biomass Valorization Using Natural Deep Eutectic Solvents: What’s New in France?

2021

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With the growing interest in more environmentally friendly solvents and processes, the introduction of Natural Deep Eutectic Solvents (NaDES) as low cost, non-toxic and biodegradable solvents represent a new opportunity for green and sustainable chemistry. Thanks to their remarkable advantages, NaDES are now arousing growing interest in many fields of research such as food, health, cosmetics and biofuels. Around the world, NaDES are seen as a promising alternative to commonly used petrochemical solvents. The objective of this review is to draw up a panorama of the existing skills on NaDES in French laboratories and industries for the valuation of natural products. This review therefore focuses on current applications, skills and perspectives, in order to analyze the place of French research in the use of NaDES for the valorization of biomass since 2015.

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“…Figure 9 presents the prepared concentrations plotted against the predicted concentrations. This representation, widely used for spectral data subjected to quantitative data analysis [45][46][47][48], provides a visualisation of the quality of the fitting achieved. With Y = 0.9499x + 0.0406 and R 2 = 0.995, the high correlation between the concentration of the AI in the dried films and the concentrations estimated using the NCLS results is confirmed.…”

Section: Distribution and Content Of Phe In Pva-gs-based Filmsmentioning

confidence: 99%

Confocal Raman Spectroscopic Imaging for Evaluation of Distribution of Nano-Formulated Hydrophobic Active Cosmetic Ingredients in Hydrophilic Films

et al. 2021

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Film-forming systems are highly relevant to the topical administration of active ingredients (AI) to the body. Enhanced contact with the skin can increase the efficacy of delivery and penetration during prolonged exposure. However, after the evaporation of volatile solvents to form a thin film, the distribution of the ingredient should remain homogenous in order to ensure the effectiveness of the formula. This is especially critical for the use of hydrophobic molecules that have poor solubility in hydrophilic films. In order to address this concern, hydroxyphenethyl esters (PHE) of Punica granatum seed oil were prepared as a nanosuspension stabilised by poloxamers (NanoPHE). NanoPHE was then added to a formulation containing polyvinyl alcohol (PVA) as a film forming agent, Glycerol as a plasticiser and an antimicrobial agent, SepicideTM HB. Despite their reliability, reference methods such as high-performance liquid chromatography are increasingly challenged due to the need for consumables and solvents, which is contrary to current concerns about green industry in the cosmetics field. Moreover, such methods fail to provide spatially resolved chemical information. In order to investigate the distribution of ingredients in the dried film, Confocal Raman imaging (CRI) coupled to Non-negatively Constrained Least Squares (NCLS) analysis was used. The reconstructed heat maps from a range of films containing systematically varying PHE concentrations highlighted the changes in spectral contribution from each of the ingredients. First, using NCLS scores it was demonstrated that the distributions of PVA, Glycerol, SepicideTM HB and PHE were homogenous, with respective relative standard deviations (RSD) of 3.33%, 2.48%, 2.72% and 6.27%. Second, the respective relationships between ingredient concentrations in the films and their Raman responses, and the spectral abundance were established. Finally, a model for absolute quantification for PHE was be constructed using the percentage of spectral abundance. The prepared %w/w concentrations regressed against predicted %w/w concentrations, displaying high correlation (R2 = 0.995), while the Root Mean Squared Error (0.0869% w/w PHE) confirmed the precision of the analysis. The mean percent relative error of 3.75% indicates the accuracy to which the concentration in dried films could be determined, further supporting the suitability of CRI for analysis of composite solid film matrix. Ultimately, it was demonstrated that nanoformulation of hydrophobic PHE provides homogenous distribution in PVA based film-forming systems independent of the concentration of NanoPHE used in the formula.

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Comparison of Raman and attenuated total reflectance (ATR) infrared spectroscopy for water quantification in natural deep eutectic solvent

Cited by 15 publications

References 78 publications

Comparison of Vibrational Spectroscopic Techniques for Quantification of Water in Natural Deep Eutectic Solvents

Comparison of Vibrational Spectroscopic Techniques for Quantification of Water in Natural Deep Eutectic Solvents

Biomass Valorization Using Natural Deep Eutectic Solvents: What’s New in France?

Confocal Raman Spectroscopic Imaging for Evaluation of Distribution of Nano-Formulated Hydrophobic Active Cosmetic Ingredients in Hydrophilic Films

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