Use Of Fourier Transform Infrared Spectroscopy Research Articles

Corrosion inhibition of mild steel in hydrochloric acid using extract of glycine max leaves

The activity of glycine max leaves extract against corrosion of mild steel in 0.5 M HCl solution has been investigated at different temperatures (298–328 K). Different measurements were done using weight loss, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM)–energy dispersive x-ray spectroscopy (EDS) and X-ray diffraction (XRD) techniques. The weight loss results indicate that glycine max leaves extract is a good inhibitor and its optimum inhibition efficiency reaches up to 91.07 % at 2 g l−1 (308 K). The adsorption of the inhibitor molecules onto the mild steel surface was found to follow the Langmuir adsorption isotherm. The values of the Gibbs free energy of adsorption strongly support physisorption of inhibitor molecules on the mild steel surface. The decrease in inhibition efficiency is observed with increasing temperature, but increases with increase in inhibitor concentration. Formation of a protective layer against acid attack on the metal surface was confirmed by use of FT-IR, XRD analysis, and SEM.

Intraoperative detection of sentinel lymph node metastases inbreast carcinoma by Fourier transform infrared spectroscopy.

Sentinel lymph node (SLN) biopsy is a routine surgical staging procedure in clinically lymph node-negative breast cancer. Fourier transform infrared (FTIR) spectroscopy, a technique based on the biochemical composition of the tissue, has previously been found to be capable of differentiating between normal and malignant tissue. The aim of the present study was to explore the intraoperative use of FTIR spectroscopy for rapidly identifying metastatic SLNs, and distinguishing between metastatic and non-metastatic tissue. Freshly removed SLNs from patients with breast cancer were analysed. Samples were measured by FTIR spectroscopy before histopathological diagnosis. The FTIR spectrum of each sample identified ten bands from 2000 to 900 cm(-1) . The peak position, intensity and full width at half maximum of each absorbent band were measured, and the relative intensity ratios calculated. Canonical discriminant analysis was performed to discriminate between metastatic and non-metastatic samples. A total of 149 SLNs were removed from 49 patients. Histopathological examination confirmed 38 metastatic and 111 non-metastatic SLNs. Eighteen of 29 parameters were significantly different between the metastatic and non-metastatic SLNs. Five parameters were selected as independent factors to form discriminant functions. The sensitivity, specificity and accuracy of this method were 94·7, 90·1 and 91·3 per cent respectively. The accuracy of histological analysis of frozen sections was 100 per cent. FTIR spectroscopy is a promising technique for the real-time diagnosis of SLN metastasis during breast cancer surgery. Surgical relevance Sentinel lymph node (SLN) biopsy is a highly accurate predictor of overall axillary status and has become the standard in disease staging in clinically node-negative breast cancer. A rapid and accurate intraoperative assessment of metastatic spread to the SLN provides the necessary information for the surgeon to proceed with immediate axillary dissection. The results of this research indicate that Fourier transform infrared (FTIR) spectroscopy is a rapid, accurate, non-destructive and cost-effective molecular method that can be used to detect SLN metastasis during surgery. FTIR analysis could be useful for the intraoperative diagnosis of lymph node metastases at large institutions, thereby reducing the workload of pathologists, as well as in regions lacking pathologists such as in developing countries.

Optimization of Extraction Techniques and RP-HPLC Analysis of Antidiabetic and Anticancer Drug Mangiferin from Roots of ‘Saptarangi’ (Salacia chinensis L.)

Saptarangi (Salacia chinensis L.) is a chief source of mangiferin, which has antidiabetic and anticancer properties. Extraction using continuous shaking extraction (CSE), ultrasonic extraction (UE), microwave assisted extraction (MAE), and steam bath assisted extraction (SBAE) were evaluated for extraction of mangiferin (MF) from roots of S. chinensis. The extracts were analyzed by reverse phase-high performance liquid chromatography (RP-HPLC) and Fourier transform-infra red spectroscopy (FT-IR) analysis. Operational parameters such as different solvents and exposure period were also evaluated. N,N-Dimethyl formamide (DMF 30%, v/v) extracted higher quantity of MF compared to other solvents. The results shows that the extraction of MF by SBAE was more efficient followed by MAE, CSE, and UE methods. Maximum quantity of MF (391.80 ppm) was obtained by SBAE technique and DMF (30%) as a solvent system. SBAE is the easiest and best method for screening of MF from S. chinensis. Furthermore, use of FT-IR validates the RP-HPLC technique for identification and quantification.

The use of FTIR spectroscopy in combination with chemometrics for the authentication of red fruit (Pandanus conoideus Lam) oil from sunflower and palm oils

Abstract In this study, Fourier transform infrared (FTIR) spectroscopy in combination with multivariate calibration based on partial least squares (PLS) has been developed for quantitative analysis of sunflower oil (SFO) and palm oil (PO) as oil adulterants in red fruit oil (RFO) for the authentication study. The binary mixtures of SFO and PO in RFO were infrared spectroscopically scanned using horizontal attenuated total reflectance at mid infrared region (4000–650 cm −1 ). Some frequency regions where the variations were observed among RFO, SFO, and PO were optimized in order to seek the best frequency regions giving the best PLS calibration models. Besides, the derivatization of FTIR spectra (fisrt and second derivatives) was also investigated in order to look the types of FTIR spectra giving the best spectral performance in the model. The results showed that SFO was better determined using FTIR normal spectra at the frequency region of 1200–1000 cm −1 with coefficient of determination ( R 2 ) of >0.99 and with root mean square error of calibration (RMSEC) of 1.42% v/v. FTIR normal spectra were also more preferred than its derivative for the quantification of PO in RFO. The R 2 value obtained for the relationship between actual value (reference value) and predicted value obtained during PLS modeling is very high (0.9991) with the low level of error (RMSEC of 0.98% v/v). It can be concluded that FTIR in combination with PLS is a reliable method for quantitative analysis of SFO and PO as adulterant in RFO for authenticity verification.

Structure and Stability of an Azoreductase with an FAD Cofactor from the Strict Anaerobe Clostridium perfringens

Azoreductase enzymes present in many microorganisms exhibit the ability to reduce azo dyes, an abundant industrial pollutant, to produce carcinogenic metabolites that threaten human health. All biochemically-characterized azoreductases, around 30 to date, have been isolated from aerobic bacteria, except for AzoC, the azoreductase of Clostridium perfringens, which is from a strictly anaerobic bacterium. AzoC is a recently biochemically-characterized azoreductase. The lack of structural information on AzoC hinders the mechanistic understanding of this enzyme. In this paper, we report on the biophysical characterization of the structure and thermal stability of AzoC by using a wide range of biophysical tools: Liquid Chromatography-Mass Spectrometry (LC-MS), Circular Dichroism Spectroscopy, Fourier-transform Infrared (FTIR) Spectroscopy, SDS-PAGE, Size Exclusion Chromatography, MALDI-TOF and UV-visible spectroscopy. We found that the flavin cofactor of AzoC is FAD, while all other structurally-known azoreductases employ FMN as a cofactor. The secondary structure of AzoC has 16% less α-helix structures, 5% more β-sheet structures and 11% more turn and unordered than the average of structurally-known azoreductase that have 10-14% sequence similarities with AzoC. We also found that oxidized AzoC is trimeric, which is unique amongst structurally known azoreductases. In contrast, reduced AzoC is monomeric, despite similarities in catalytic activity and thermal stability of oxidized and reduced AzoC. Our results show that the use of FTIR spectroscopy is crucial for characterization of the β-sheet content in AzoC, illustrating the need for complementary biophysical tools for secondary structural characterization of proteins.

Use of Fourier transform-infrared spectroscopy to predict spoilage bacteria on aerobically stored chicken breast fillets

In this research work we explored the potential of mid infrared (MIR) spectroscopy to determine spoilage microorganism on the surface of chicken breast fillets that were kept aerobically at 5 °C for 0, 1, 2, 3, 5 and 8 days, and at 15 °C for 0, 0.5, 1, 2, 3 and 5 days. It is shown that MIR spectroscopy (4000 – 1000 cm−1 range) coupled with attenuated total reflectance (ATR) accessory can be used directly on the surface of meat samples to produce fingerprints. Culture dependent methods were used to determine total viable count (TVC), Pseudomonas, Enterobacteriaceae and Brochothrix thermosphacta on chicken breast fillets at each step of the 2 kinetics. In parallel, MIR spectra were recorded. For each kinetic, partial least square discriminant analysis (PLSDA) results showed 100% of good classifications for the six investigated storage times using 4 PLS factors. PLS regression was carried out to predict the microbial counts from the MIR spectral data. Using PLS model with four factors, good correlation (R2 = 0.99) and very small root mean squares error of validation (between 0.01 and 0.97 log cfu/cm2) showed a strong correlation between MIR spectral data sets and the results obtained using traditional methods.

The Use of FTIR Spectroscopy and Chemometrics for Rapid Authentication of Extra Virgin Olive Oil

AbstractThe authenticity of high value edible fats and oils including extra virgin olive oil (EVOO) is an emerging issue, currently. The potential employment of Fourier transform infrared (FTIR) spectroscopy in combination with chemometrics of multivariate calibration and discriminant analysis has been exploited for rapid authentication of EVOO from canola oil (Ca‐O). The optimization of two calibration models of partial least square (PLS) and principle component regression was performed in order to quantify the level of Ca‐O in EVOO. The chemometrics of discriminant analysis (DA) was used for making the classification between pure EVOO and EVOO adulterated with Ca‐O. The individual oils and their blends were scanned on good contact with ZnSe crystals in horizontal attenuated total reflectance, as a sampling technique. The wavenumbers of 3,028–2,985 and 1,200–987 cm−1 were used for quantification and classification of EVOO adulterated with Ca‐O. The results showed that PLS with normal FTIR spectra was well suited for quantitative analysis of Ca‐O with a value of the coefficient of determination (R2) > 0.99. The error, expressed as root mean square error of calibration obtained was relatively low, i.e. 0.108 % (v/v). DA can make the classification between pure EVOO and that adulterated with Ca‐O with one misclassified reported.

Real-Time Feedback Control Using Online Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy for Continuous Flow Optimization and Process Knowledge

The use of automated continuous flow reactors is described, with real-time online Fourier transform infrared spectroscopy (FT-IR) analysis to enable rapid optimization of reaction yield using a self-optimizing feedback algorithm. This technique has been applied to the solvent-free methylation of 1-pentanol with dimethyl carbonate using a γ-alumina catalyst. Calibration of the FT-IR signal was performed using gas chromatography to enable quantification of yield over a wide variety of flow rates and temperatures. The use of FT-IR as a real-time analytical technique resulted in an order of magnitude reduction in the time and materials required compared to previous studies. This permitted a wide exploration of the parameter space to provide process understanding and validation of the optimization algorithms.

Diagenetic changes in Lake Superior sediments as seen from FTIR and 2D correlation spectroscopy

Isotopic and elemental analysis, Fourier transform infrared spectroscopy (FTIR), principal components analysis (PCA) and two dimensional (2D) correlation analysis, where core depth was used as perturbation, were used to study the diagenesis of organic matter (OM) in Lake Superior sediments. Changes in OM composition were examined at five lake stations over a depth range of 0–10cm. PCA results show that depth-related changes among sites are similar, leading to an increased contribution from inorganic (and possibly refractory aromatic organic) components at each site, and a loss of contribution from other organic components. Synchronous spectra reveal that aliphatic esters and carbohydrates are degraded significantly with increasing depth, leading to an increased contribution from clay/biogenic silica/inactive carbohydrates. Asynchronous spectra show that, in general, carboxyl groups, including aliphatic ester and amide in protein, are degraded first, followed by a group of carbohydrates and then aromatic compounds and/or the SiO framework in clay and biogenic silica. Site dependent compositional variation occurs and appears to be influenced by topography and geology, e.g. the delivery of a larger load of terrestrial inorganic silicate minerals to certain sites and re-suspension/re-deposition, leading to less intensive down core variation at mid-lake central and eastern basin sites. The study demonstrates the usefulness of FTIR coupled with PCA and 2D correlation approaches for exploring structural changes in sedimentary material during diagenesis.

Correlation of chemical and physical properties of an Alaska heavy oil from the Ugnu formation

Physical properties and chemical components of an Alaska heavy oil from the Ugnu formation were studied by viscosity measurements, molecular beam mass spectrometry (MBMS), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR). The viscous samples rheology was measured between −10°C and 60°C using small amplitude oscillatory shear tests for viscosity, which generally decreases with increasing temperature. An activation energy of viscosity was measured as between 85 and 92kJ/mol. The screening method by combined use of FTIR, NMR and a time-resolved MBMS identified several component classes: water, cyclo/straight alkanes, alkenes, mono and multi-ring aromatic molecules, as well as small fractions of other organic molecules. Azeotropic behavior was observed between 100 and 250°C. The partial least squares correlation between molecular masses and the viscosity shows that water, alkylbenzene, and molecules with higher masses have positive correlations to the viscosity, but that the aliphatic molecules were anti-correlated.

Application of Fourier Transform Infrared Spectroscopy for Authentication of Functional Food Oils

In recent years, the authentication of edible fats and oils has become an important issue for food producers, consumers, and regulatory authorities due to religious and economic reasons. Some high-priced edible oils such as extra virgin olive oil (EVOO), virgin coconut oil (VCO), and cod liver oil (CLO) are adulterated with lower price oils to improve profits. These oils can be considered functional food oils due to their beneficial effects on human health. Fourier transform infrared (FTIR) spectroscopy combined with suitable chemometrics techniques has emerged as a potential tool that allows analysts to authenticate high-value edible oils. This review describes the potential use of FTIR spectroscopy for authentication of three functional food oils, namely, EVOO, VCO, and CLO.

A study of the subchronic effects of arsenic exposure on the liver tissues of Labeo rohita using Fourier transform infrared technique

In this work, an attempt has been made to study the subchronic effects of arsenic exposure on the biochemical composition; mainly proteins of the liver tissues of Labeo rohita fingerlings by using Fourier transform infrared (FT-IR) spectroscopic technique. The study was carried out using a Perkin Elmer-Spectrum Rx1 spectrometer. Because of arsenic exposure, significant reductions in the intensity as well as area of amide bands have been observed in the liver tissues. The decreased intensity of the amide bands could be interpreted as the result of alteration of the protein synthesis due to the high affinity of metal compounds towards different amino acid residues of proteins. Further, meso-2, 3-dimercaptosuccinic acid (DMSA) treatment shows the recovery of the protein content in the liver tissues. To confirm that the changes observed are only due to the bio-accumulation of arsenic, the concentration of arsenic in the liver tissues of Labeo rohita was determined by using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). It is observed that the arsenic level in the control tissues is found to be below detectable limit, whereas the arsenic exposed liver shows an accumulation of 66.68 ± 0.43 μg/g and DMSA treatment reduces the arsenic content to 17.96 ± 0.19 μg/g. In conclusion, this study gives clear evidence that the use of FT-IR spectroscopy is a powerful approach to achieve more insight into the protein alterations caused by arsenic.

The use of FTIR spectroscopy to assess quantitative changes in the biochemical composition of microalgae

A mid-infrared spectroscopic method was developed for the simultaneous and quantitative determination of total protein, carbohydrate and lipid contents of microalgal cells. Based on a chemometric approach, measured FTIR (Fourier transform infrared) spectra from algal cells were reconstructed by a partial least square algorithm, using the spectra of the reference substances to determine their relative contribution to the overall cell spectrum. From this specific absorption, absolute macromolecular cell composition [pg cell(-1)] can be calculated using calibration curves, which have been validated by independent biochemical methods. The future potential of this method for photosynthesis research is shown by its application to follow time-resolved changes in the cellular composition of microalgae during an illumination period of several hours. We show how the macromolecular composition can be investigated by FTIR spectroscopy methods. This can substantially increase the efficiency of screening processes like bioreactor monitoring and may be beneficial in metabolic engineering of algal cells.

Use of Fourier Transform Infrared Spectroscopy and Chemometric Data Analysis To Evaluate Damage and Age in Mushrooms (Agaricus bisporus) Grown in Ireland

The aim of this research was to investigate whether the chemical changes induced by mechanical damage and aging of mushrooms can be (a) detected in the midinfrared absorption region and (b) identified using chemometric data analysis. Mushrooms grown under controlled conditions were bruise-damaged by vibration to simulate damage during normal transportation. Damaged and nondamaged mushrooms were stored for up to 7 days postharvest. Principal component analysis of Fourier transform infrared (FTIR) spectra showed evidence that physical damage had an effect on the tissue structure and the aging process. Random forest classification models were used to predict damage in mushrooms producing models with error rates of 5.9 and 9.8% with specific wavenumbers identified as important variables for identifying damage, and partial least-squares (PLS) models were developed producing models with low levels of misclassification. Modeling postharvest age in mushrooms using random forests and PLS resulted in high error rates and misclassification; however, random forest models had the ability to correctly classify 82% of day zero samples, which may be a useful tool in discriminating between "fresh" and old mushrooms. This study highlights the usefulness of FTIR spectroscopy coupled with chemometric data analysis in particular for evaluating damage in mushrooms and with the possibility of developing a monitoring system for damaged mushrooms using the FTIR "fingerprint" region.

Use of FTIR and mass spectrometry for characterization of glycated caseins

This study investigates the potential of Fourier transform infrared spectroscopy (FTIR) to monitor glycation-induced changes in protein structure. Aqueous solutions of sodium caseinate and glucose (1:2 w/w, pH 6.7) were heated at 90 degrees C for 0, 10, 20, 40 and 60 min. Evidence for caseinate glycation was obtained by mass spectrometry techniques (electrospray (ESI) and matrix-assisted laser desorption ionisation (MALDI)). FTIR was able to discriminate between glycated and non-glycated sodium caseinate, when the data were analysed by multivariate statistical methods; principal component analysis (PCA) and soft independent modelling of class analogy (SIMCA). The techniques used were complementary and provided different levels of information about the glycated samples.

Infrared spectroscopy: a reagent-free method to distinguish Alzheimer's disease patients from normal-aging subjects

The physiopathogenesis of Alzheimer's disease (AD) is related to various biochemical mechanisms that may be reflected by changes in plasma components. In the current study, Fourier transform-infrared (FT-IR) spectroscopy was used to identify these biochemical variations by monitoring spectral differences in the plasma of 40 AD patients compared with those of 112 control subjects. A hierarchical classification in the whole mid-infrared region allowed a clear separation between AD and controls (C) that was optimized by using a restricted spectral range (1480-1428 cm(-1)). Spectral changes confirmed vibration differences between AD and C mostly related to modified lipid and nucleic acid structures involved in oxidative stress-dependent processes of AD. Moreover, the analysis of samples in the 1480-910-cm(-1) region allowed the distinction between C and AD with an accuracy of 98.4% and showed 2 subgroups C(1) and C(2) within the C group. Interestingly, the C(1) subgroup was located closer to the AD group than the C(2) subgroup, which suggests biochemical differences within the nondemented subjects. Biochemical studies revealed a significant increase in a specific marker of oxidative stress, F8-isoprostanes (8-epi-PGF2alpha) levels, in the plasma of AD patients as compared with total controls and subgroup C(2) but not subgroup C(1). Thus, these results suggest that use of FT-IR spectroscopy could be valuable to distinguish AD patients from normal-aging subjects.

Virgin and recycled engine oil differentiation: A spectroscopic study

As a result of the changes that occur during their use, used engine oils tend to differ in chemical and physical composition from a virgin oil. In general recycled oils have: much higher water and sediment levels than virgin oil; relatively higher concentrations of organic compounds (oxidation products); and relatively higher levels of metals such as Fe, Cd, Cr, Pb, etc. Therefore, the aim of this work was to investigate, assess and to observe, by means of the physical and the chemical properties of the oils, atomic absorption (AA), inductive couple plasma (ICP) and Fourier transform infrared (FTIR) analyses the extent of the differences occurring between the virgin and recycled oil. In important part of this work was also the development of analytical techniques based on the use of FTIR spectroscopy; in relation to the rapid analysis of lubricants; in particular for the differentiation of virgin and recycled oil. The results obtained were expected to be useful for differentiation purposes, providing information on whether the metal concentrations and oxidation products could be an appropriate feature for differentiating a particular oil sample from the others. This work is categorized into a two-step procedure. Firstly, an evaluation of a typical FTIR spectrum of an engine oil sample (mono- and multigrade) is presented. The broad feature centered at 1716 cm −1 is due to the presence of carbonyl containing degradation products of oil. A band observed at 1732, 1169, 1154 and 1270 cm −1 assigned to the polymethacrylate stretching vibrations, allows the determination of viscosity modifier and pour point depressant additives. The observed differences in the specific spectral bands (1732, 1169, 1154 and 1270 and 1716 cm −1) are investigated and discussed. Secondly, an analytical technique for the measurement of the levels of the wear metals is also applied.

Use of FTIR spectroscopy to distinguish between capsular types and capsular quantities in Streptococcus pneumoniae

Fourier transform infrared (FTIR) spectroscopy has shown remarkable ability in distinguishing between bacterial species and identifying bacterial colony structures, when used in tandem with methods such as cluster analysis, principal component analysis, or linear discriminant analysis. The present work was aimed to evaluate the potential of FTIR-microscopy (FTIR-MSP) to distinguish between different serotypes and capsular quantities of Streptococcus pneumoniae. In general, the results obtained have consistently proven that the spectral information at the region 900-1,185 cm(-1) was sufficient to distinguish between various pneumococcal serotypes. Moreover, the method was able to differentiate between S. pneumoniae phase variants on the basis of their relative carbohydrate content. The unsupervised cluster analysis of the samples showed differences, not only in the carbohydrate content, but also in the region 1,350-1,480 cm(-1), which is dominated by absorptions due to lipids and phospholipids. This approach proved to be useful for the distinction between S. pneumoniae serotypes and between phase variants, which were shown to acquire different pathogenic capacity.

Analysis of covariance patterns in gene expression data and FT-IR spectra

The aim of this study was to detect and interpret correlation patterns in several large data matrices from the same biological system using Partial Least Squares Regression (PLSR) in order to get information on the system under investigation. To do this, DNA microarray data and Fourier Transform Infrared (FT-IR) spectra from a designed study where Campylobacter jejuni was exposed to environmental stress conditions, were used. The experimental design included variation in atmospheric conditions, temperature and time. PLSR was first used to analyse each of the two data types separately in order to explore the effect of the experimental parameters on the data. The results showed that both the gene expression and FT-IR spectra were affected by the variations in atmosphere, temperature and time, but that the effect was different for the two types of data. When the DNA microarray data and FT-IR spectra were linked together by PLSR, covariation due to temperature was seen. Both specific genes and ranges in the FT-IR spectra that were connected to the variation in temperature were detected. Some of these are possibly connected to properties of the cell wall of the bacteria. The results in this study show the potential of PLSR for investigation of covariance structures in biological data. By doing this, valuable information about the biological system can be detected and interpreted. It was also shown that the use of FT-IR spectroscopy provided important information about the stress responses in the bacteria, information that was not detected from the DNA microarray data.

Application of Fourier transform infrared spectroscopy for monitoring hydrolysis and synthesis reactions catalyzed by a recombinant amidase

This study demonstrates the use of Fourier transform infrared (FTIR) spectroscopy for monitoring both synthesis and hydrolysis reactions catalyzed by a recombinant amidase (EC 3.5.1.4) from Pseudomonas aeruginosa. The kinetics of hydrolysis of acetamide, propionamide, butyramide, acrylamide, benzamide, phenylalaninamide, alaninamide, glycinamide, and leucinamide were determined. This revealed that very short-chain substrates displayed higher amidase activity than did branched side-chain or aromatic substrates. In addition, on reducing the polarity and increasing the substrates’ bulkiness, a reduction of the amidase affinity for the substrates took place. Using FTIR spectroscopy it was possible to monitor and quantify the synthesis of several hydroxamic acid derivatives and ester hydrolysis products. These products may occur simultaneously in a reaction catalyzed by the amidase. The substrates used for the study of such reactions were ethyl acetate and glycine ethyl ester. Hydroxylamine was the nucleophile substrate used for the synthesis of acetohydroxamate compounds. Results presented in this article demonstrate the usefulness of FTIR spectroscopy as an important tool for understanding the enzyme structure–activity relationship because it provides a simple and rapid real-time assay for the detection and quantification of amidase hydrolysis and synthesis reactions in situ.