FTIR-ATR Technique Research Articles

Spectroscopic techniques and chemometrics for ink analysis: Document analysis application

This study represents a methodology to determine the falsified documents via a combined method of spectroscopic techniques and chemometrics. The techniques of UV–Vis and FTIR-ATR spectroscopies and principal component analysis methods have been applied to black, blue, and red ballpoint pens available in the Türkiye market. The analysis results of the applied spectroscopic techniques were found to be consistent with each other for the examined eleven ink samples from three different brands, and it was observed that FTIR-ATR spectroscopy had higher discriminative power. A dried sample preparation technique developed for small amounts of samples for FTIR-ATR measurements and the increased the sensitivity of FTIR-ATR technique was associated with this sample preparation method. Statistical techniques showed that the UV–Vis technique proves useful outcomes in distinguishing inks according to their colors, whereas the FTIR-ATR technique is valuable for identifying ink brands. Additional analysis of the sub-brand of black inks and falsified old-dated check sample analysis validated that our methodology has the potential to classify and identify ballpoint inks in forensic applications. Due to the limited sample quantity available for analysis in real samples, only FTIR-ATR analysis was possible, and the results demonstrated that document forgery could be detected from small parts of samples in the document. When we look at the overall outcome of this study, a comprehensive methodology enriched with statistical calculations has been proposed that can be applied even in a laboratory with limited resources, having only UV–Vis and FTIR-ATR capabilities.

Bio-Innovative Modification of Poly(Ethylene Terephthalate) Fabric Using Enzymes and Chitosan.

This article investigates the activation of surface groups of poly(ethylene terephthalate) (PET) fibers in woven fabric by hydrolysis and their functionalization with chitosan. Two types of hydrolysis were performed-alkaline and enzymatic. The alkaline hydrolysis was performed in a more sustainable process at reduced temperature and time (80 °C, 10 min) with the addition of the cationic surfactant hexadecyltrimethylammonium chloride as an accelerator. The enzymatic hydrolysis was performed using Amano Lipase A from Aspergillus niger (2 g/L enzyme, 60 °C, 60 min, pH 9). The surface of the PET fabric was functionalized with the homogenized gel of biopolymer chitosan using a pad-dry-cure process. The durability of functionalization was tested after the first and tenth washing cycle of a modified industrial washing process according to ISO 15797:2017, in which the temperature was lowered from 75 °C to 50 °C, and ε-(phthalimido) peroxyhexanoic acid (PAP) was used as an environmentally friendly agent for chemical bleaching and disinfection. The influence of the above treatments was analyzed by weight loss, tensile properties, horizontal wicking, the FTIR-ATR technique, zeta potential measurement and SEM micrographs. The results indicate better hydrophilicity and effectiveness of both types of hydrolysis, but enzymatic hydrolysis is more environmentally friendly and favorable. In addition, alkaline hydrolysis led to a 20% reduction in tensile properties, while the action of the enzyme resulted in a change of only 2%. The presence of chitosan on polyester fibers after repeated washing was confirmed on both fabrics by zeta potential and SEM micrographs. However, functionalization with chitosan on the enzymatically bioactivated surface showed better durability after 10 washing cycles than the alkaline-hydrolyzed one. The antibacterial activity of such a bio-innovative modified PET fabric is kept after the first and tenth washing cycles. In addition, applied processes can be easily introduced to any textile factory.

An approach towards identification of leather from leather-like polymeric material using FTIR-ATR technique

AbstractLeather, a by-product of the meat industry, has unique strength, elasticity, water vapor permeability, resistance to abrasion, durability, and longevity. In the background of ISO 15115:2019, the authenticity of leather has become a subject matter of concern. There is a need to distinguish leather (animal origin) from other leather-like materials derived from fossil fuel (PU, faux leather, etc.) and agro-product-driven vegan materials, which are also sold in the market as leather. For this purpose, this work relies on the signature FTIR bands of collagen (the skin-making protein) as a starting point to distinguish between animal origin and rest. A detailed investigation of all types of materials used in lifestyle products has been carried out to assess the boundary lines of this hypothesis. It is reasonably concluded that the signature Amide I, II, and III bands of collagen occurring at 1600, 1500, and 1200 cm−1 could serve as the first line to distinguish against all materials other than nylon and in the case of nylon, and the Amide A band at 3200 cm−1, forms the basis for differentiation from nylon. In essence, the FTIR spectra can be used as a robust, easy and unambiguous technique to distinguish leather from leather-like materials currently available on the market. Graphical Abstract

The Quantitative Analysis of Ethanol-based Hand Sanitizers and Prediction of Methanol Adulteration Using FTIR-ATR Technique

The Quantitative Analysis of Ethanol-based Hand Sanitizers and Prediction of Methanol Adulteration Using FTIR-ATR Technique

From Collection or Archaeological Finds? A Non-Destructive Analytical Approach to Distinguish between Two Sets of Bronze Coins of the Roman Empire.

This study stems from the need for numismatics to establish whether there may be relationships between a group of 103 bronze coins from the Roman era found in archaeological excavations on the Cesén Mountain (Treviso, Italy) and a group of 117 coins kept at the Museum of Natural History and Archaeology in Montebelluna (Treviso, Italy). The chemists were delivered six coins with neither pre-agreements nor further information on the origin of the coins. Therefore, the request was to hypothetically assign the coins to the two groups on the basis of similarities and differences in their surface composition. Only non-destructive analytical techniques were allowed to be used to characterize the surface of the six coins taken blindly from the two sets. The elemental analysis of each coins' surface was carried out by µ-XRF. To better observe the morphology of the coins' surfaces, SEM-EDS was used. Compounds covering the coins coming from both corrosion processes (patinas) and the deposition of soil encrustations were also analyzed by means of the FTIR-ATR technique. The molecular analysis confirmed the presence of silico-aluminate minerals on some coins, unequivocally indicating a provenance from clayey soil. Some soil samples, collected from the archaeological site of interest, were analyzed to verify whether the encrusted layer on coins could contain chemical components compatible with them. This result, together with the chemical and morphological investigations, led us to subdivide the six target coins into two groups. The first group is made up of two coins coming from the set of coins from excavation (found in the subsoil) and from the set from open air finds (coins found in the top layer of the soil). The second group is made up of four coins that are devoid of characteristics corresponding to exposure to soil contact for long periods of time and, moreover, their surface compounds could suggest a different provenance. The analytical results of this study made it possible to correctly assign all six coins to the two groups of finds and support numismatics, which was unconvinced in considering all coins to come from the same finding site only on the basis of archaeological documentations.

Characterisation of the Phenolic Profile of Acacia retinodes and Acacia mearnsii Flowers' Extracts.

Acacia spp. is an invasive species that is widespread throughout the Portuguese territory. Thus, it is pertinent to better understand this species in order to find different applications that will value its use. To evaluate the phenolic profile in Acacia flowers, ethanolic extracts obtained through an energized guided dispersive extraction were analysed, focusing on two species, Acacia retinodes and Acacia mearnsii, at two flowering stages. The phytochemical profile of each extract was determined by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and high-performance liquid chromatography coupled with diode array detector. The FTIR-ATR technique was used to distinguish the different samples’ compositions. The results showed the presence of high concentrations of phenolic compounds (>300 mg GAE/g extract), among which are flavonoids (>136 mg QE/g extract), for all combinations of species/flowering stages. The phytochemical profile showed a complex composition with 21 compounds identified and quantified (the predominant ones being epicatechin, rutin, vanillin, and catechol). Both species and flowering stages presented significant variations regarding the presence and quantity of phenols and flavonoids, so much so that a principal component analysis performed with FTIR-ATR spectra data of the extracts was able to discriminate between species and flowering stages.

FTIR-ATR spectroscopic, thermal and microstructural studies on polypropylene-glass fiber composites

This study presents the results of examinations of polypropylene-glass fiber composites. Polypropylene matrix composites containing 30% and 50% glass fiber were tested. Part of the material was subjected to heat treatment consisting of annealing. Depending on how polymeric materials are obtained, their physical and mechanical properties change over a wide range. Their understanding and interrelation between each other depend on accurate quantitative structural assessment at both the chain and elemental cell microstructural levels and the supramolecular level. FTIR-ATR technique was used to identify the characteristic functional groups present in the chemical structure of polypropylene and composites based on its matrix. Structure analysis at the supramolecular level was performed using differential scanning calorimetry (DSC) and temperature microscopic examinations. These examinations allowed for the evaluation of thermal parameters such as melting point and crystallization temperature of the polymer matrix in the composites studied. Furthermore, by analyzing the values of thermal effects determined using the DSC method, it was possible to determine the degree of crystallinity. A deeper understanding of the interdependence between the structure and properties of polymers allows to predict the characteristics of the final product and enables optimization of technological processes.

Surface Properties of Plasma-Activated Chitosan Foils

Thin films of chitosan are often deposited on various surfaces to provide them with antiseptic properties. In the presented research, chitosan foils were obtained using two methods and treated with nitrogen plasma. The obtained materials were characterized by measuring the wettability of the test liquids, and the apparent surface free energy was calculated using the Tadmor equilibrium contact angles. The surface topography was characterized using optical profilometry and SEM. On the other hand, the effect of plasma on surface groups was investigated using the FTIR-ATR technique. Plasma activation of the surface increases the polarity of the surface. This is observed in the changed surface roughness and the share of functional groups on the surface.

Effect of 2,2,2-trifluoroethyl methacrylate: Triethyleneglycol dimethacrylate ratio on functional properties of Bis-GMA hybrid composites

This study aimed to investigate the effect of 2,2,2-trifluoroethyl methacrylate:triethyleneglycol dimethacrylate (TFEMA: TEGDMA) ratio on various functional properties of Bis-GMA/TFEMA:TEGDMA/UDMA composites. The experimental composites were loaded with 70% (weight% of total monomer) fillers consisting of silanised fumed silica, zirconia, and strontium fluoride. The light-cured composites were analysed for degree of conversion by FTIR-ATR technique, volumetric shrinkage in according to the Archimedes' principle, and fluoride ion release and recharge capacity by ion selective electrode. Water sorption, water solubility, and flexural strength were determined in accordance with ISO 4049 standard. Results showed that the degree of conversion, fluoride release and recharge capacity, water sorption, water solubility increased, and polymerization shrinkage decreased, with increasing TFEMA:TEGDMA ratio. Besides, twofold increase in flexural strength was observed for composite with the highest TFEMA content.

Micro-DSC, FTIR-ATR and NMR MOUSE study of the dose-dependent effects of gamma irradiation on vegetable-tanned leather: The influence of leather thermal stability

Leather artefacts, archaeological, historical or modern, are prone to microbiological attack which could lead to irreversible degradation. Previous studies performed on new leather mock-ups indicated good resistance of leather at doses up to (25–50) kGy. The aim of this research is to improve our understanding about the changes in the thermal stability and structural order of collagen within vegetable-tanned leather exposed to gamma irradiation. Variously vegetable-tanned leather samples were therefore exposed to irradiation with Co-60 gamma-rays with increasing doses (10–100 kGy) and the dose-dependent effect on collagen-tannin matrix was investigated using micro-DSC, the best technique for determining proteins' thermal stability, coupled with FTIR-ATR and NMR MOUSE spectroscopy, to enhance the analytical coverage of the calorimetric profile. FTIR-ATR technique revealed the very subtle changes in collagen at the molecular (lower order) level by, which are reflected in the properties of the structures with a higher level of order, namely the hydrothermal stability of fibrils (measured by micro-DSC) and mobility of macromolecular chains (determined by NMR MOUSE). It was proved that a 10 kGy dose causes significant variation on collagen molecular structure, fibrils hydrothermal stability, and macromolecular chain's mobility when the collagen-tannin matrix is already thermally destabilized and present a wide distribution of collagen populations with distinct thermal stability. On the other hand, leathers characterized by high thermal stability and homogeneous distribution of collagen populations better withstood radiation up to either 25 kGy or 50 kGy, depending on the collagen-tannin interactions' strength. This protocol, with high analytical and diagnostic sensitivity, can thus be applied to characterize a broader range of collagen materials sterilized/crosslinked with gamma radiation.

Preparation and characterization of porous polyethersulfone (PES) membranes with improved biocompatibility by blending sulfonated polyethersulfone (SPES) and cellulose acetate (CA) – A comparative study

The current study focuses on the effective sulfonation of polyethersulfone (PES) polymer to synthesize sulfonated-polyethersulfone (SPES) and blending with PES to prepare SPES/PES blend membranes as well as preparation of cellulose acetate CA/PES blend membranes. FTIR-ATR technique was used to confirm the blending of SPES and CA into PES matrix. Water contact angle studies showed a significant reduction of hydrophobicity in SPES blend membranes (49.55 ± 1.52°) as compared with CA blend membranes (59.42 ± 2.20°) and PES base membranes (67.80 ± 1.48°). The presence of pores were analysed using scanning electron microscopy (SEM) where significant changes in the membrane morphology in the blend membranes were observed. Platelet adhesion, protein adsorption and activated partial thromboplastin time (APTT) studies were used to assess hemocompatibility of the membranes in which SPES/PES membranes exhibited improved characteristics as compared with its counterparts. The cytocompatibility of membranes were evaluated using water soluble tetrazolium (WST) assay which confirmed that both SPES/PES and CA/PES blend membranes exhibit better cytocompatibility than base PES membrane

Short term monitor of photodegradation processes in ranitidine hydrochloride observed by FTIR and ATR-FTIR

The effects of degradation of ranitidine hydrochloride exposed to UVB radiation (λ = 310 nm) and oxygen in a weathering chamber were studied by Fourier Transform Infrared spectroscopy (FTIR) and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR). ATR-FTIR profile indicated that the degradation was spatially heterogeneous. Significant amounts of photoproducts were detected only in a directly irradiated layer. Major damage/change was reflected in the appearance of broad, extended group of signals near the wavenumber 3600-3200 cm-1 or/and 3500-3400 cm -1. We examined whether FTIR-ATR technique is a great tool to observe the simplest and the first changes on the surface of a substance in powder.

Application of FTIR-ATR to discriminate peach nectars with higher and lower sugar contents

Abstract Fruit juice does not have the same nutritional value as fresh fruit with regards to the vitamin, mineral and dietary fibre contents and the antioxidant properties. However, it can be part of a healthy diet if it is produced with the minimal addition of sugar. This study aimed to evaluate the performance of the FTIR-ATR technique to discriminate the authenticity (concerning the addition of other pulps) and amount of sugar in peach nectars. This technique is usually used in food analysis because it does not require sample preparation, is quick and allows for the determination of several parameters with a single sample aliquot. The nutritional information provided on the labels of 69 samples of 23 different brands of commercial peach juice, was analysed. The differences in the nutritional composition and in the ingredients were determined according to an analysis of the labels. The largest differences observed between the samples were the sugar contents, the percentages of pulp and the addition of other pulps. All samples were analysed by FTIR-ATR equipped with a controlled temperature flow-through cell. The spectral multivariate analysis suggested it was possible to identify differences in the amount of sugar present and identify the presence of fruit pulps other than peach.

Thermo-Oxidative Behavior of Carbon Black Composites for Self-Regulating Heaters

The composite materials for self-regulating heaters are conductive composites based on a polymer matrix and a dispersed conductive filler consisting in either carbon black or another carbon material, such as graphite or nanotubes. Similar materials are suitable for sensors and current limitations. As these materials used in heating applications work usually at elevated temperatures in presence of air, the ageing processes would be an important limiting factor of their lifetime. Therefore, thermal oxidation processes and crystallinity changes during the service of these products are of major interest in durability studies. The potential interference of carbon-based materials with the oxidation and ageing of polymer matrix shall be known in order to correctly estimate the durability of such materials. The effect of radiation exposure is studied taking into account the potential use of such materials in radiation environments. In this work, the activation energies of some initial, unaged and aged products at elevated temperatures are compared in order to characterize the effect of thermo-oxidative ageing and hence to evaluate their durability. The effect of some antioxidants is also discussed. The crystallinity, calculated from DSC was used for evaluation of the physical changes induced within the aged materials, following the procedures described in previous work. FTIR-ATR technique was used for characterization of chemical changes induced by ageing.

ATR-FTIR FOR DISCRIMINATION OF ESPRESSO AND AMERICANO COFFEE PODS

Roasted and ground coffee for encapsulation in single-serve capsules compatible with keurig® and coffee powder obtained from Nespresso® commercial capsules were analyzed for pH value, titratable acidity, moisture content, water activity and color (lightness); a data matrix that contains the physicochemical properties and the absorbance measurements using a baseline of 1600 to 1800 cm–1 by FTIR-ATR technique, was evaluated through the combined methods of principal component analysis (PCA) and cluster analysis in order to discriminate between the types of capsules. In the PCA biplot two distinct groups can be identified and in the cluster analysis two groups are that correspond to the two types of capsules. The results showed that FTIR-ATR based methods seem to be a promising alternative for the discrimination of coffee samples for the pods industry or for the type of consumption.

A rapid ATR-FTIR spectroscopic method for classification of gelatin gummy candies in relation to the gelatin source.

Gelatin is widely used in gummy candies because of its unique functional properties. Generally, porcine and bovine gelatins are used in the food industry. FTIR-ATR combined with chemometrics analysis such as hierarchical cluster analysis (HCA) (OPUS Version 7.2 software), principal component analysis (PCA) (OPUS Version 7.2 software) and partial least squares-discriminant analysis (PLS-DA) (Matlab R2017b) were used for classification and discrimination of gelatin gummy candies related to their gelatin source. The spectral region between 1734 and 1528 cm-1 was selected for chemometric analysis. The potential of FTIR spectroscopy for determination of bovine and porcine source in gummy candies was examined and validated by a real-time polymerase chain reaction (PCR) method. Twenty commercial samples were tested by developed ATR-FTIR methodology and RT-PCR technique, mutually confirming and supporting results were obtained. Gummy candies were classified and discriminated in relation to the bovine or porcine source of gelatin with 100% success without any sample preparation using FTIR-ATR technique.

FTIR-ATR spectroscopy as a diagnostic tool in the diagnosis of hypercholesterolemia induced by cholesterol-rich diet in rats

Clinical Diagnosis is the process that identifies a possible disease or disorder that can be diagnosed through analysing specific components with multiple techniques and procedures that identifies the internal physiological changes. FTIR-ATR is a non-invasive, reagent-free diagnostic tool which can be rapidly and simultaneously analyze several components in the biological fluids and organs and which can be employed in analyzing the biomolecules. Hypercholesterolemia was induced in albino rats by feeding the animals with the regular diet supplemented with 1% cholesterol and 0.5 % cholic acid saturated with coconut oil for 6 weeks. End of induction study, experimental animals were sacrificed for biochemical and FTIR- ATR spectral analysis. Experimental serum samples were analyzed immediately for spectral recordings in the Mid IR region of 4000-450 cm-1. The intensity of the olefinic =CH bond (3012 cm−1) can be used as an index of relative concentration of double bonds in the lipid structure from unsaturated lipids. The C=O stretching at 1740 cm−1 monitor the glycerol backbone near the aqueous part of the lipids. Results on biochemical variations obtained with both these methods were compared. Based on results obtained the study suggest that the FTIR-ATR technique might be an additional technique to know more details at molecular levels in the diagnostic sector. Further, this technique could be standardised for routine utility in disease diagnosis and management in the medicinal field.

Efficacy of an Ayurvedic Drug Thyronil over Thyroid Disorder using Blood Samples by FTIR-ATR technique

Efficacy of an Ayurvedic Drug Thyronil over Thyroid Disorder using Blood Samples by FTIR-ATR technique

Hygroscopicity of internally mixed particles glycine/NaNO3 studied by FTIR-ATR technique

Internal mixed aerosol particles in atmosphere often take the drastic physical property changes owing to interactions between compositions. Hygroscopicity and phase transition behavior of mixed particles composed of glycine and NaNO3 with different organic to inorganic molar ratios (OIRs) have been investigated by using Fourier transform infrared attenuated total reflection spectroscopy (ATR-FTIR). It is found that pure glycine particles effloresce when the relative humidity (RH) is ∼64.5% and do not deliquesce on humidifying. The efflorescence and deliquescence point for pure NaNO3 particles are ∼54% RH and ∼91.9% RH, respectively. For the internal mixed glycine/NaNO3 particles, there exhibit various hygroscopicities and solid-aqueous phase transitions dependent upon the OIR. When the OIRs are 2:1 and 1:1, NaNO3 particles cannot crystallize. When the OIRs are 1:2, 1:4 and 1:8, crystalline ratios are ~31%, ~45% and 72%, NaNO3 effloresce at ∼44.7% RH, ~35.2% RH and ~35% RH, respectively. For all studied mixture particles, glycine can crystallize. For OIRs of 2:1, 1:1, 1:2, 1:4 and 1:8, the crystalline fractions of glycine are ~78%, 89%, 93%, 94% and 95%, respectively, corresponding to the ERH range of 74% − 42%, 73% − 35.9%, 65.5% − 19.2%, 35.2% − 8.1% and 35% − 3.8%. It shows that both NaNO3 and glycine crystals are favored by more enriched NaNO3. On hydration, the DRHs of NaNO3 for mixtures with OIR of 1:2, 1:4 and 1:8 are ~87.4%, ~87% and 85.4%, respectively. Glycine in mixtures deliquesces at ~99% (incomplete deliquescence), ~98.3%, ~97.3%, ~93.3%, ~85.4% RH, respectively, with decreasing OIR. The results suggest the positive effect of NaNO3 on the deliquescence of glycine and NaNO3.

A novel spectroscopic analysis to detect photochemical reaction of the bronchodilator – Doxofylline and its estimation in pharmaceutical formulation

Photostability studies of drugs and drug products are an integral part of the product development process in the pharmaceutical industry. These studies are carried out to ensure quality, efficacy and safety of the formulated products during manufacture, storage and use. In this investigation, a novel spectroscopic approach has been adopted by employing the FTIR-ATR and UV/Visible techniques to detect the photochemical reactions of the drug Doxofylline, chemically designated as 7-(1, 3 dioxolane-2-yl methyl) theophylline, in its raw (pure) form. Significant changes were observed in terms of optical density of the absorption bands and a satisfactory analysis has been performed using ANOVA Statistics. It highlights the role of the photochemistry of drugs with respect to its spectral profiles and also explains photo physical processes. In addition; the drug compatibility study was also undertaken by using FTIR-ATR technique which indicated that there were no interactions occurring between the raw sample of the drug and the excipients used in the preparation of the pharmaceutical formulation. With this, UV–visible spectroscopic method was validated for the quantitative estimation of Doxofylline in pharmaceutical dosage forms and was performed with λmax at 274nm. Calibration curves were linear between the concentration range 10–50μg/ml. The various parameters such as linearity, precision, accuracy, recovery and specificity were studied according to ICH guidelines (Ahmed et al., 2016; Jain et al., 2011; ICH, 1996).