Infrared Spectroscopy Methods Research Articles

Hydrophilic platinum(II) complexes containing 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine: Spectroscopic and in vitro cytotoxic characterization

Mononuclear platinum(II) complexes with 5,7-methyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) of the general formula cis-[Pt(X)2(dmtp)2], where X - acetate (1), trichloroacetate (2), trifluoroacetate (3), nitrate (4) have been synthesized and characterized by multinuclear magnetic resonance (1H, 13C, 15N, 195Pt) and infrared spectroscopy methods. Spectroscopic parameters indicated the presence of the PtO2N2 chromophore system with two monodentate N(3)-bonded 5,7-methyl-1,2,4-triazolo[1,5-a]pyrimidines, and two monodentate O-donor ligands (carboxylate or nitrate).A cytotoxicity assay of hydrophilic platinum(II) complexes (1–4) against three human tumour cell lines A549 (non-small cell lung carcinoma), T47D (breast cancer), HT-29 (colon adenocarcinoma), and normal murine embryonic fibroblast cells (BALB/3T3) was performed.Considering the cytotoxic parameters of the studied complexes, the best in vitro results against the human breast tumour cells (T47D) were found for cis-[Pt(OOCCCl3)2(dmtp)2] although all the tested complexes (except complex (4)) exhibited moderate in vitro activity.

INVESTIGATION OF THE FEATURES OF THE SURFACE STRUCTURE OF TWODIMENSIONAL LAYERED MATERIALS Ti3C2Tx (T — ОН, О, F) BY INFRARED SPECTROSCOPY AND RAMAN SPECTROSCOPY METHODS

The methods of infrared (IR) spectroscopy and Raman spectroscopy (RS) are herein used to characterize the features of the surface state of Ti3C2Tx (T = OH–, O2–, F–) layered materials obtained in the form of powder and two-dimensional (2D) particles forming a stable colloidal solution. A powdered sample of Ti3C2Тх is obtained by removing aluminum from Ti3AlC2 by treatment in an HF solution, 2D Ti3C2Тх particles are obtained by treating Ti3AlC2 in an HCl+LiF solution followed by sonication. The phase composition and morphology of the samples are studied by X-ray diffraction and electron microscopy. The IR and Raman spectroscopy methods permitted to differentiate the presence of terminal groups (O2–, OH–, F–) of various nature with a quantitative predominance of the OH form in the Ti3C2Tx powder sample and OH and fluoride ions in 2D Ti3C2Tx particles, and also detect the presence of TiOx impurities.

Crystal Chemistry, Isomorphism, and Thermal Conversions of Extra-Framework Components in Sodalite-Group Minerals

Isomorphic substitutions of extra-framework components in sodalite-group aluminosilicate minerals and their thermal conversions have been investigated using infrared, Raman, electron spin resonance (ESR), as well as ultraviolet, visible and near infrared (UV–Vis–near IR) absorption spectroscopy methods and involving chemical and X-ray diffraction data. Sodalite-related minerals from gem lazurite deposits (haüyne, lazurite, and slyudyankaite) are characterized by wide variations in S-bearing extra-framework components including SO42− and various polysulfide groups (S2●−, S3●−, S4●− radical anions, and S4 and S6 neutral molecules) as well as the presence of CO2 molecules. Heating at 700 °C under reducing conditions results in the transformation of initial S-bearing groups SO42− and S3●− to a mixture of S2−, HS−, S2●−, and S4●− and transformation of CO2 to a mixture of CO32− and C2O42− or HC2O4− anionic groups. Further heating at 800 °C in air results in the decomposition of carbonate and oxalate groups, restoration of the SO42− and S3●− groups, and a sharp transformation of the framework. The HS− anion is stable only under reducing conditions, whereas the S3●− radical anion is the most stable polysulfide group. The HS−-dominant sodalite-group mineral sapozhnikovite forms a wide solid-solution series with sodalite. The conditions required for the formation of HS−- and CO20-bearing sodalite-group minerals are discussed.

Sugar-cubic Fe2O3/nitrogen-doped graphene nanocomposite as high-performance anode material for oxygen evolution reaction

Industrial application of water electrolysis has called for the development of oxygen evolution electrocatalysts that are low-cost, stable and have low overpotential. Substituting the precious metal catalysts with more accessible transition metal oxide such as Fe2O3 is a key solution for applications in water electrolysis. Here, we show an efficient modified electrode for oxygen evolution, which be developed by co-electrodeposition of graphene oxide and Fe2O3 nanoparticles directly onto macroporous nickel foam substrate. Then, using an electrochemical procedure, in-situ electro-polymerization of pyrrole and graphene oxide reduction are performed on the electrode surface. The sugar-cubic Fe2O3 nanoparticles are also prepared by the hydrothermal method. The morphology and structure of the Fe2O3 nanoparticles and Fe2O3/ graphene nanocomposites are characterized by Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray spectroscopy (EDX), Fourier Transform Infra-Red spectroscopy (FT-IR), X-Ray Diffraction (XRD), Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS) methods. Moreover, the OER activities of the synthesized catalysts are investigated by using Linear Sweep Voltammetry (LSV), Chronopotentiometry (CP) and Electrochemical Impedance Spectroscopy (EIS) methods. The electrocatalytic activity of the sugar-cubic Fe2O3/nitrogen-doped graphene nanocomposite prepared by hydrothermal method in alkaline media shows outstanding advantages, so that its over potential was 313 mV and its Tafel slope was 81 mV/dec.

Development and IR spectroscopic Analysis of Composite Materials Based on Poly(Methyl Methacrylate) and Chitosan

Poly (methyl methacrylate) (PMMA) and chitosan composites were synthesized by means of the mechanochemical method. In addition, PMMA–chitosan films were obtained in polar (water) and non-polar (benzene) solvents. Obtained polymer composites were analyzed by the Fourier transform infrared spectroscopy method using the ATR attachment with diamond crystal. The presence of intermolecular hydrogen bonds in formation of PMMA and chitosan polymer composites was shown. С=О group of PMMA and OH and NH2 groups of chitosan molecule take part in the formation of hydrogen bonds.

Exploration of the Crystal Structure and Thermal and Spectroscopic Properties of Monoclinic Praseodymium Sulfate Pr2(SO4)3.

Praseodymium sulfate was obtained by the precipitation method and the crystal structure was determined by Rietveld analysis. Pr2(SO4)3 is crystallized in the monoclinic structure, space group C2/c, with cell parameters a = 21.6052 (4), b = 6.7237 (1) and c = 6.9777 (1) Å, β = 107.9148 (7)°, Z = 4, V = 964.48 (3) Å3 (T = 150 °C). The thermal expansion of Pr2(SO4)3 is strongly anisotropic. As was obtained by XRD measurements, all cell parameters are increased on heating. However, due to a strong increase of the monoclinic angle β, there is a direction of negative thermal expansion. In the argon atmosphere, Pr2(SO4)3 is stable in the temperature range of T = 30–870 °C. The kinetics of the thermal decomposition process of praseodymium sulfate octahydrate Pr2(SO4)3·8H2O was studied as well. The vibrational properties of Pr2(SO4)3 were examined by Raman and Fourier-transform infrared absorption spectroscopy methods. The band gap structure of Pr2(SO4)3 was evaluated by ab initio calculations, and it was found that the valence band top is dominated by the p electrons of oxygen ions, while the conduction band bottom is formed by the d electrons of Pr3+ ions. The exact position of ZPL is determined via PL and PLE spectra at 77 K to be at 481 nm, and that enabled a correct assignment of luminescent bands. The maximum luminescent band in Pr2(SO4)3 belongs to the 3P0 → 3F2 transition at 640 nm.

Uptake and Presence Evaluation of Nanoparticles in Cicer arietinum L. by Infrared Spectroscopy and Machine Learning Techniques

The aim of this work was to study the applicability of infrared spectroscopy combined with machine learning techniques to evaluate the uptake and distribution of gold nanoparticles (AuNPs) and single-walled carbon nanotubes (CNTs) in Cicer arietinum L. (chickpea). Obtained spectral data revealed that the uptake of AuNPs and CNTs by the C. arietinum seedlings’ root resulted in the accumulation of AuNPs and CNTs at stem and leaf parts, which consequently led to the heterogeneous distribution of nanoparticles. principal component analysis and support vector machine classification were applied to assess its usefulness for evaluating the results obtained using the attenuated total reflectance-Fourier transform infrared spectroscopy method of C. arietinum plant grown at different conditions. Specific wavenumbers that could classify the different nanoparticle constituents of C. arietinum plant extracts according to their ATR-FTIR spectra were identified within three specific regions: 450–503 cm−1, 750–870 cm−1, and 1022–1218 cm−1, based on larger PCA loadings of C. arietinum ATR-FTIR spectra with distinct spectral differences between samples of interest. The current work paves a path to the future fabrication strategies for AuNPs and single-walled CNTs via plant-based routes and highlights the diversity of the applications of these materials in bio-nanotechnology. These results indicate the importance of family-plant selection, choice of methods, and pathways for the efficient biomolecule delivery, drug cargo, and optimal conditions in the wide spectrum of bioapplications.

Determination of active ingredients in alcohol‐based gel by spectroscopic techniques and chemometric analysis

AbstractThe international public health emergency related to COVID‐19 caused by the SARS‐CoV‐2 virus has altered several production and registration criteria for sanitary products, including alcohol‐based hand sanitizers. In this work, we investigate the concentration of alcohol in sanitizers presented in gel form applying the principal component regression method on measurements using Infrared and Raman spectroscopic methods. The chemometric calibration is performed using isopropanol or ethanol as active agents, and the method is used to characterize several commercial samples. Furthermore, the results of the prediction of alcohol concentration, obtained by applying the principal component regression and partial least squares methods, in the spectroscopic techniques, were compared with each other and with the results provided by nuclear magnetic resonance. Our results show that spectroscopic techniques coupled with principal component regression are fast, low‐cost, and safe tools for the determination of alcohol concentration, regardless the gelling agent used.

New sensitive ambient mass spectrometric method combined with chemometric modelling for the analysis of Equisetum palustre L. contaminations in the traditional herb Equiseti herba

The aim of this study was to develop a new and sensitive ambient mass spectrometric method in combination with multivariate data analysis to classify and quantify contaminations of the traditional herb Equiseti herba through the similar looking E. palustre. Due to its morphological similarity and the often-overlapping habitats, mix-ups of the two plants are common. This is concerning since E. palustre contains substances that are potentially toxic to humans, such as the piperidine alkaloids palustrine and palustridiene. Next to macroscopic and microscopic examination, the identification of Equiseti herba in the European Pharmacopoeia is carried out by means of thin layer chromatography, which must detect up to 5% of foreign compounds. The results of the chemometric models were built from the mass spectrometric data. Furthermore, they were compared with a near infrared spectroscopy method combined with multivariate data analysis, since this type of spectroscopy has already been established in quality control. As a result, the linear discriminant model obtained from the mass spectrometric data could classify an independent set of artificial contaminations of E. arvense through E. palustre with high correctness as low as 1% dry weight contamination grade. In addition, quantification through a partial least square model showed adequate results for a location of the grade of contamination. In conclusion, the new ambient mass spectrometric method presents itself superior to the respective near infrared method and the chemometric models built from its data as well as the official thin layer chromatography of the European Pharmacopoeia.

Simulation and Testing of the Radiation Performance of SiC Particles with Different Distribution Morphologies

Based on Mie scattering theory, fractal theory, the generalized multiparticle Mie model and the attenuated total reflectance infrared spectroscopy method, this paper aimed to explore the influence of different distribution morphologies of semiconductor nanoparticles on their radiation properties. The results revealed that (1) the symmetry and fluctuation amplitude of the scattering direction of the SiC elementary particles, with a diameter of 100 nm, and the cluster particles were related to the wavelength, particle size and agglomeration state. (2) The particle size distribution had a significant effect on the spectral extinction performance of the SiC particles, especially when λ > 10 μm, which can be greatly strengthened by increasing the proportion of large-scale particles. (3) The influence of SiC particle clusters on their spectral extinction was directly related to the cluster size and wavelength. When λ < 10 μm, small-scale cluster particles showed lower extinction performances; however, the absorption and scattering factors increased with the increase in cluster size while λ > 10 μm, and the extinction performance significantly improved. In summary, the quantitative changes in the microscale and structure, as well as the distribution states, had a significant impact on the infrared spectral characteristics of the particles, and we expect to adjust the particle size distribution to obtain desired radiation properties.

Evaluation of portable near-infrared spectroscopy for authentication of mRNA based COVID-19 vaccines.

Since its identification in 2019, Covid-19 has spread to become a global pandemic. Until now, vaccination in its different forms proves to be the most effective measure to control the outbreak and lower the burden of the disease on healthcare systems. This arena has become a prime target to criminal networks that spread counterfeit Covid-19 vaccines across the supply chain mainly for profit. Counterfeit vaccines provide false sense of security to individuals, heightens the risk of exposure and outbreak of the virus, and increase the risk of harm linked to Covid-19 infection. Moreover, the increase in counterfeit vaccines feeds hesitancy towards vaccination and erodes the trust in mass immunisation programmes. It is therefore of paramount importance to work on rapid and reliable methods for vaccine authentication. Subsequently this work utilised a portable and non-destructive near infrared (NIR) spectroscopic method for authentication of Covid-19 vaccines. A total of 405 Covid-19 vaccines samples, alongside their main constituents, were measured as received through glass vials. Spectral quality and bands were inspected by considering the raw spectra of the vaccines. Authentication was explored by applying principal component analysis (PCA) to the multiplicative scatter correction-first derivative spectra. The results showed that NIR spectra of the vaccine featured mainly bands corresponding to the mRNA active ingredient. Fewer bands corresponded to the excipients and protein spectra. The vaccines NIR spectra were strongly absorbing with maximum absorbances up to 2.7 absorbance units and that differentiated them from samples containing normal saline only (constituent reported for counterfeit Covid-19 vaccines). Clustering based on PCA offered optimal authentication of Covid-19 vaccines when applied over the range of 9000–4000 cm-1These findings shed light on the potential of using NIR for analysing Covid-19 vaccines and presents a rapid and effective initial technique for Covid-19 vaccine authentication.

Identification of human hair wigs and animal hair wigs by the method of near infrared spectroscopy modeling

The near infrared spectrogram of human hair wigs and animal hair wigs was measured with a Fourier near infrared spectrometer. In addition, a qualitative model for the identification of human hair wigs and animal hair wigs with their near infrared spectrogram has been established. The effectiveness of spectral preprocessing with chemometric techniques including standard normal variable, second derivative and Norris smoothing has been analyzed through principal component analysis. The results showed that the accuracy of the discriminant model could reach 100%, indicating that the near infrared spectroscopy method is highly applicable and effective for the identification of human hair wigs and animal hair wigs.

Development of novel spectroscopic and machine learning methods for the measurement of periodic changes in COVID-19 antibody level

In this research, blood samples of 47 patients infected by COVID were analyzed. The samples were taken on the 1st, 3rd and 6th month after the detection of COVID infection. Total antibody levels were measured against the SARS-CoV-2 N antigen and surrogate virus neutralization by serological methods. To differentiate COVID patients with different antibody levels, Fourier Transform InfraRed (FTIR) and Raman spectroscopy methods were used. The spectroscopy data were analyzed by multivariate analysis, machine learning and neural network methods. It was shown, that analysis of serum using the above-mentioned spectroscopy methods allows to differentiate antibody levels between 1 and 6 months via spectral biomarkers of amides II and I. Moreover, multivariate analysis showed, that using Raman spectroscopy in the range between 1317 cm−1 and 1432 cm−1, 2840 cm−1 and 2956 cm−1 it is possible to distinguish patients after 1, 3, and 6 months from COVID with a sensitivity close to 100%.

A deep look into the diverse surface speciation of the mono-molybdate/lepidocrocite system by ATR-IR and polarized ATR-IR spectroscopy

The present study is focused on the adsorption of monomeric molybdate anions on the surface of lepidocrocite investigated by several infrared spectroscopy methods. To study the surface speciation of molybdates on lepidocrocite, the behavior of the anion at the interface upon increasing anion concentration (fixed pH) or decreasing pH (fixed concentration) was analyzed in situ. The obtained results expand the knowledge for surface speciation by revealing a second molybdate complex, which is more stable, arising from the interaction with defects on the (010) facets of lepidocrocite. A curve fitting procedure enabled us to confirm what is observed from the pristine spectra, and outer-sphere complexes were probed as well. The evolution of the different bands upon increasing adsorbate concentration and decreasing pH, as obtained by curve fitting, shows a complex evolution for the different surface species with protonation, with the formation of strongly bonded complexes at low pH. The 2D synchronous and asynchronous spectra support the interpretation of the data. Furthermore, insights into the orientation of the complexes with respect to the lepidocrocite surface are obtained by using linearly polarized radiation. The results confirm most of the conclusions ascertained on the basis of the unpolarized spectra. The combination of the different methodologies yields a consistent picture for the complexity of this system and paves the way for subsequent utilization of this approach to study other systems.

Towards practical integration of MBR with electrochemical AOP: Improved biodegradability of real pharmaceutical wastewater and fouling mitigation

In the current study, we report enhanced treatment of real pharmaceutical wastewater by integration of Electrooxidation (EO) with Membrane Bio-Reactor (MBR) for the first time. Integrated pre-pilot EO-MBR plant consisted of a 3D printed electrochemical flowcell equipped with graphite electrodes installed in the effluent recirculation line of an MBR equipped with a hollow fiber membrane module. Results demonstrated that 5 V was the optimum voltage level for an isolated EO system. Isolated EO system led to 40% COD removal and 2.5 fold biodegradability index (BOD5/COD) improvement after 24 hr treatment at the optimum voltage of 5 V and 160 mL.min−1 flowrate. Almost complete removal of COD and BOD5 was observed for the EO-MBR system with 160 mL.min−1 recirculation rate and 24 hr HRT, while respective values were 60 and 87% for the MBR system at same operational conditions. Oxidation of pharmaceutical compounds identified in real wastewater and the fate of main oxidation-recalcitrant by-products were confirmed using liquid chromatography techniques. In addition, the integrated EO-MBR system led to significant membrane fouling mitigation with a 28 day extended operational time before reaching the Trans Membrane Pressure (TMP) limit value of 30 kPa. Measurements revealed reduced Extracellular Polymeric Substances (EPS) Concentration of membrane sludge cake layer of EO-MBR along with significant reduction of proteinaceous compounds in the LB-EPS fraction of cake layer in comparison with isolated MBR system. Fouling behavior improvement of the EO-MBR system was attributed to the electrophilic attack of electrochemically generated hydroxyl radicals to the electron-rich moieties of EPS organic foulants. Reduced proteinaceous/humic-like substances of LB-EPS from the cake layer were further confirmed by Emission Excitation matrix (EEM) and Fourier Transform InfraRed (FTIR) spectroscopic methods. The results of current research provide a helpful basis for future studies by elucidating the complex operating/fouling mechanism of integrated Advanced Oxidation Processes (AOPs) with MBR systems for enhanced treatment of organics polluted wastewaters with low biodegradability.

Separation of wax fraction in asphalt binder by an improved method and determination of its molecular structure

The crystalline wax in asphalt binder has obvious influence on the low temperature performance of the asphalt pavement, and it is essential to adopt an accurate and efficient method to separate crystalline wax from asphalt binder. In this paper, the optimum eluted solvents used for the separation of the wax fraction are determined by the solubility parameters, and the reduced pressure column chromatography method is developed through the improvement of existing methods. It was discovered that the efficiency and accuracy of the experiment had been greatly improved with the higher repeatability and recovery of the saturates and aromatics. On this basis, the average molecular structures of the saturate and aromatic wax fraction were determined by the gas chromatography-mass spectrometry (GC–MS), gas chromatography-flame ionization detector (GC-FID), nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopy methods. The smaller degree of the branch chain of the wax fraction would attribute to the larger content of the crystalline wax in asphalt binder, which could provide a compositional mechanism explanation for the physical hardening (thermoreversible ageing) of the asphalt binder at the low temperature.

Environmentally friendly dyeing of wool yarns using of combination of bio‐mordants and natural dyes

AbstractToday, the issue of reducing industrial pollution has received much attention. The textile industry is of high important throughout the world. However, its by‐product wastewater pollutes the environment. The first approach was the selection of plant‐based dyes (madder and reseda) and the application of tannin‐based mordants (pomegranate peel and myrobalan). The extraction of madder, reseda, and pomegranate peel in water with the ultrasound‐assisted method was done. In this article, pre‐mordanting method was used for mordanting and Cu (copper) and alum were selected as the mineral mordant to compare the results. Fourier Transform Infrared Spectroscopy method was employed to analyze the obtained extracts and to investigate the changes in the fibers. The results showed that K/S (color strength) values of the dyed samples increased by increasing the dye concentration. The colorfastness properties of the samples were investigated according the ISO standards.

PCz/BaO nanocomposites: Synthesis, characterization, and energy storage properties

This study focuses on both synthesis and structural characterization of polycarbazole/barium oxide (PCz/BaO) nanocomposites and the determination of their frequency-based electrical properties such as complex permittivity, tangent loss, and alternating current (ac) conductivity. While PCz was synthesized by using carbazole monomers, BaO nanoparticles (NPs) were obtained by using the co-precipitation method. PCz matrix and BaO NPs were examined by scanning and transmission electron microscopes, X-ray diffraction, and Fourier Transformed Infrared Spectroscopy methods. The electrical properties of the PCz/BaO nanocomposites showed that the energy storage ability of the PCz can be improved with the addition of BaO NPs up to 10 wt% at the low frequencies. Furthermore, the 2.5 wt% BaO NPs contribution causes an increase in ε′ and a decrease in ε'' of PCz. Additionally, it has been determined that BaO NPs doping significantly increases the ac conductivity of the PCz matrix in the low- and mid-frequency regions.

Discrimination of Radix Astragali according to geographical regions by data fusion of laser induced breakdown spectroscopy (LIBS) and infrared spectroscopy (IR) combined with random forest (RF)

Data fusion of Laser-induced breakdown spectroscopy (LIBS) and infrared spectroscopy (IR) combined with random forest (RF) was proposed to identify Radix Astragali from different geographical regions. Firstly, the LIBS and IR spectra of 19 Radix Astragali samples were collected and analyzed. Then, an unsupervised discriminant model based on principal components analysis (PCA) with single LIBS and IR spectra was applied to identify Radix Astragali. The results indicated that three types of Radix Astragali samples can not be accurately distinguished using PCA. To distinguish Radix Astragali accurately, a supervised discriminant model based on RF was applied to identify Radix Astragali. The optimal RF discriminant models based on single LIBS or IR were obtained by selecting appropriate pretreatment methods. In low-level data fusion, the optimal LIBS and IR spectra were concatenated into a matrix to construct RF discriminant model. In mid-level data fusion, feature variables were extracted by variable importance (VI) measurement on basis of low-level fused data and the optimal variables were used as input variables to construct RF discriminant model. The results indicated that the predictive performance of RF model based on data fusion was better than the single LIBS or IR method. The predictive performance of RF model based on mid-level data fusion was best and the corresponding sensitivity, specificity and accuracy for the test set were 0.9667, 0.9833 and 0.9778. Additionally, the modeling time was 6.9 s. Summarily, RF model on basis of data fusion of LIBS and IR can provide a rapid and accurate discriminant method for the Radix Astragali from different regions.

Prediction of crosslink density of prevulcanised latex using NIR Spectroscopy based on combination of fractional order derivative (FOD) and variable selection methods

Rapid method in measurement of crosslink density is required in factory. The objective of this study was to develop the prediction model of crosslink densities based on near infrared (NIR) spectroscopy method. The prediction models were developed using partial least squares regression (PLSR) with spectral pre-treatment of fractional order derivatives (FOD) and variable selection methods including successive project algorithm (SPA) and genetic algorithm (GA). The result demonstrated that prevulcanised (PV) latex model had higher accuracy than that of PV50 latex model. Effective model in predicting crosslink densities of PV and PV50 latices could be pre-processed with FOD=1 and 0.75, respectively. The prediction model generated with full wavelength had the standard error of cross validation (SECV) of 3.21% and 3.52%, respectively. The model performance of PV latex could improve with variable selection method of GA which reduced the SECV from 3.21% to 3.17% and number of wavelengths reduced from 1059 to 937. The model performance of PV50 could not reduce by using the variable selection method. However, the GA could reduce the number of wavelengths from 1059 to 216.