Infrared Spectroscopy Methods Research Articles

Effect of iron oxide loading on the phase transformation and physicochemical properties of nanosized mesoporous ZrO2

Mesoporous ZrO2-supported iron oxide materials were prepared with nominal loadings of iron oxide of 5, 10, 15 and 20wt.% using a modified co-precipitation method. The physicochemical properties of the catalysts were characterized by thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, Raman spectroscopy, high resolution transmission electron microscopy, N2 adsorption, X-ray photoelectron spectroscopy and infrared spectroscopy methods. A delay in the ZrO2 phase transformation as a result of the incorporation of iron was determined using TG/DSC measurements. XRD, Raman spectroscopy and HRTEM results revealed that an increase of iron oxide loading from 5 to 15wt.% enhanced the transformation of the monoclinic to tetragonal phase. Unexpectedly, 20wt.% iron oxide loading was required for complete tetragonal structure stabilization due to the mesoporosity of the ZrO2 support. Iron oxide loadings from 5 to 15wt.% showed an increase in the BET-surface area due to the presence of amorphous iron oxide on the surface. XPS and FTIR results indicated that increasing the iron oxide content to 20wt.% resulted in stabilization of the tetragonal zirconia phase as a result of surface-to-bulk migration and incorporation of Fe3+ ions in the ZrO2 lattice.

Ferric Chloride Assisted Thermal Stabilization of Polyacrylonitrile Precursor Fibers Prior to Carbonization

The effect of ferric (Fe3+) ion incorporation on the thermal stabilization of polyacrylonitrile (PAN) fibers was investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction analysis and infrared spectroscopy methods. The results obtained from the DSC and TGA measurements indicated that there was an improvement in thermal stability when Fe3+ ions were incorporated into the polymer structure. TGA thermograms showed a relative improvement in thermal stability as indicated by increasing carbon yield with progressing time. The degree of lateral order and apparent crystallite size estimated by X-ray diffraction decreased with increasing stabilization time. Incorporation of Fe3+ induced distinct changes in the infrared spectra of the thermally stabilized PAN fibers. The spectral changes appeared to be due to the formation of coordination bonds between the nitrogen atom of the nitrile group and Fe3+. The formation of ferric ion-nitrile coordination bonds accelerated thermal stabilization by catalyzing the occurrence of dehydrogenation, cyclization and oxidation reactions.

Thermal and Infrared Studies of Garnierite from the Soroako Nickeliferous Laterite Deposit, Sulawesi, Indonesia

DOI: 10.17014/ijog.v7i2.137Mineralogical characterization of some garnierite samples from Soroako have been conducted using X-ray diffraction, thermal analysis, and infrared spectroscopy methods. XRD patterns reveal the samples mainly containing the mixture of kerolite (talc-like phase) and serpentine with minor smectite, sepiolite, and silica. Thermal analyses of garnierite samples indicated by DTA curves are in good agreement with patterns that have been reported in literature. Three endothermic peaks normally occur in the ranges between 58º C and <800º C illustrating three steps of weight losses: adsorbed, bound, and hydroxyl/crystal water. One additional weight loss in low temperature region of sepiolite is corresponding to the lost of zeolitic water. Infrared spectra appeared in 3800 - 3200 cm-1 region generally exhibit broad absorption bands, indicating low crystallinities of studied samples and can be assigned to the presence of hydroxyl group bonded to octahedral coordination mainly Mg atom. The bands observed at 1660 cm-1, 1639 cm-1, 1637 cm-1, and 1633 cm-1 in all samples indicate water molecules. FTIR spectra displaying the strong bands at 1045 cm-1, 1038 cm-1, and 1036 cm-1 could be related to the presence of Si-O-Si bonds linking to tetrahedral coordination. The strong absorption bands appeared at 511 cm-1, 505 cm-1, 499 cm-1, and 496 cm-1 in respective samples are attributed to divalent cation bonds (e.g. Mg, Ni-O). Both TG/DTA and FTIR seem to be the powerful tool in diagnosing the crystal chemistry of garnierite which is mainly composed of phyllosilicate minerals.

Discrimination of different genuine Danshen and their extracts by Fourier transform infrared spectroscopy combined with two-dimensional correlation infrared spectroscopy

In this study, six varieties of Danshen from different populations and genuine (“Daodi” in Chinese transliteration) regions were discriminated and identified by a three-step infrared spectroscopy method (Fourier transform-infrared spectroscopy (FT-IR) coupled with second derivative infrared spectroscopy (SD-IR) and two dimensional correlation infrared spectroscopy (2D-IR)). Though only small differences were found among the FT-IR spectra of the six Danshen samples, the positions and intensities of peaks at 3393, 3371, 1613, 1050, and 1036cm−1 could be considered as the key factors to discriminate them. More significant differences were exhibited in their SD-IR, particularly for the peaks around 1080, 1144, 695, 665, 800, 1610, 1510, 1450, 1117 and 1077cm−1. The visual 2D-IR spectra provided dynamic chemical structure information of the six Danshen samples with presenting different particular auto-peak clusters, respectively. Moreover, the contents of salvianolic acid B in all samples were measured quantitatively by a validated ultra performance liquid chromatography (UPLC), which was consistent with the FT-IR findings. This study provides a promising method for characteristics and quality control of the complicated and extremely similar herbal medicine like Danshen, which is more cost effective and time saving.

Renal stone analysis : patient findings and Fourier Transform infrared spectroscopy method validation : peer reviewed original article

Abstract The aim of this study was to validate the Fourier Transform infrared spectroscopy (FTIR) method used for renal stone analysis, establish prevalence of renal stones and to obtain demographic information on patients presenting with renal stones. Renal stones are analyzed by FTIR to determine the constituents of the stones, in order to assist with the appropriate treatment of the patient and prevent a recurrence of stone formation. Validation of methods is important to ensure accurate reported results. The majority of the renal stones analyzed consisted of calcium in some form and the prevalence of stones was much higher in men (75%) than in women, which correlates to findings in other studies. The method is fit for the purpose of renal stone analysis using standard or mini pellets.

Prediction of β-glucosidase and β-glucosaminidase activities, soil organic C, and amino sugar N in a diverse population of soils using near infrared reflectance spectroscopy

There is a need for methods that can rapidly measure multiple biological properties simultaneously. A near infrared spectroscopy (NIRS) method was used to predict β-glucosidase (EC 3.2.1.21) and β-glucosaminidase (NAGase, EC 3.2.1.52) activities, and soil organic C and amino sugar N concentrations in 184 diverse soils of Ohio. The laboratory-measured values of the variables were calibrated against NIR spectral data with partial least squares regression analysis. Statistical analysis of the spectral data was done using the multivariate analysis software Unscrambler 8.0 (CAMO Inc). The first differential transformation of the spectral data in the NIR region (1100–2498nm) generally yielded best results for developing multivariate calibration models. The multivariate models developed were validated using the full cross validation method and the test set method with a test set size of approximately 45 samples. The R2 values, testing variation between concentrations as measured by the NIR method and chemical methods, were 0.91 for organic carbon (OC), 0.92 for amino sugar N, and 0.82 for both soil β-glucosidase and β-glucosaminidase enzyme activities. Our study showed that the NIRS method has the potential to simultaneously, rapidly and accurately predict values of multiple related variables. The equipment needed for the NIRS method is not expensive and can be used where very large numbers of samples need to be rapidly analyzed. Indeed, the prediction equations can be constantly improved as more data points are entered into the correlations between laboratory-measured values and NIRS values.

Robustness of the near infrared spectroscopy method determined using univariate and multivariate approach.

The robustness assessment is a part of a method validation protocol, during which several characteristics of an analytical method are also evaluated (e.g. accuracy, repeatability, reproducibility, linearity, intermediate precision, measurement uncertainty) in order to assess its fitness for purpose. The purpose of robustness assessment of the near infrared spectroscopy method (NIRS) is to indicate which factor significantly influence the obtained results, as well as to point to the potential problems that might occur in the routine application of the method. The assessment of robustness of the NIRS method included variation of certain operational and environmental factors at three level (-1,0,1) by applying univariate (one-variable-at-a-time, OVAT) and multivariate (multivariate-at-a-time, MVAT) approach to the experimental design. Operational and environmental factors that were varied included the number of subsamples to be measured in the NIRS measurement (1), environmental temperature (2), sample temperature (3), environmental air humidity (4), instrument voltage (5) and lamp aging (6). Regardless the applied experimental design, external factors with significant influence on obtained NIRS results were indicated, as well as pointed the potential problems that might occur in the routine application of the method. In order to avoid them, every effort should be made to stabilize instrument and sample temperature and to standardize the homogeneity and number of subsamples to be measured in NIRS measurement. Moreover, the obtained results highlighted the necessity that the NIRS instruments should work through a voltage regulator.

Study of carbon black obtained by pyrolysis of waste scrap tyres

Waste scrap tyres were thermally decomposed under various conditions. Decompositions were followed by the TGA method. Specific heating regimes were tested to obtain optimal structural properties of resulting pyrolytic carbon black produced by pyrolysis of scrap tyres and the process was characterized in temperature interval from 380 to 1,200 °C and heating rate 10, 20 and 50 °C min−1 under nitrogen atmosphere. The original scrap tyres and pyrolytic carbon black were characterized by Raman and Fourier transform infrared spectroscopy methods. Textural properties were also determined. Effect of temperature and heating rate on process of pyrolysis of scrap tyres was observed. Shifting of temperature of maximum pyrolysis rate to lower value and spreading of DTG peak is caused by increasing heating rate. Temperature 570 °C was sufficient for total scrap tyres pyrolysis. Graphitic and disordered structure was distinguished in the formed carbon black by Raman spectroscopy. With increasing temperature, heating rate and weight loss, the amount of the graphitic structure was reduced at the expense of disordered structure. Destruction of nonporous scrap tyres and formation of porous structure took place at higher temperature. Porous carbon black is formed above 380 °C, specific surface area increased up to 88 m2 g−1.

Characterization of Nanodispersed Graphite

The work is devoted to the questions of interrelations between methods of functionalization and to the distribution character of functional groups on the surface of nanographite plates. The functionalization of initial thermoexfoliated graphite (TEG) is carried out with the use of inorganic reagents such as KMnO4 solutions in the sulfuric acid or a mixture of sulfuric and nitric acids and during different times of first and re-dispersion in a magnetic stirrer. The quantitative and qualitative compositions of functional groups on the surface of nanographite plates are determined by infrared spectroscopy method. As it is revealed from the detailed studies of a structure of functionalized graphite, the functionalization results in the destruction of the initial TEG structure and a reduction of the size of TEG particles down to several nanometers.

Estimation of appendicular muscle mass and fat mass by near infrared spectroscopy in older persons

Near infrared spectroscopy has been reported to have a high reliability and accuracy in assessing the percentage of body fat. However, whether muscle mass can be accurately estimated using this method has not been established. This study examined whether a near infrared spectroscopy method could estimate appendicular muscle mass and fat mass, with dual-energy X-ray absorptiometry as the standard method for comparison. A total of 20 orthopedic inpatients (mean age 73.2 ± 6.8 years) were recruited for this study. Their body composition was assessed using near infrared spectroscopy and dual-energy X-ray absorptiometry. Appendicular muscle mass and fat mass were estimated from height, weight and optical densities. The optical densities for the upper arm (biceps, triceps) and forearm (flexor carpi radialis) were significantly correlated with appendicular muscle mass (r = 0.534 to 0.623) or fat mass (r = -0.483 to -0.827). Estimated appendicular muscle mass and fat mass explained 89% and 80% of the variance in the dual-energy X-ray absorptiometry-derived muscle mass and fat mass estimates using height, weight and optical density values of the proximal flexor carpi radialis. Near infrared spectroscopy is a useful method to assess not only fat mass, but also muscle mass in older adults.

Classification of Maize Kernel Hardness Using near Infrared Hyperspectral Imaging

Maize is an internationally important food crop that is usually milled before use. Milling yield is strongly influenced by maize hardness which, in turn, is controlled by the relative proportions of vitreous and floury endosperm within a single kernel. Current conventional near infrared (NIR) spectroscopic methods for determining maize hardness require reference data, which is obtained by destroying multiple kernels. In contrast, NIR hyperspectral imaging (NIR-HSI) has shown promise for determining the hardness of individual maize kernels without sample destruction or the need for reference data. This is possible due to the spatial dimension, in addition to the spectral dimension, offered by NIR-HSI. To illustrate this, NIR-HSI was used to characterise regions of germ, vitreous endosperm and floury endosperm from both the endosperm-rich (germ-down; GD) and endosperm-poor (germ-up; GU) surfaces of 155 single maize kernels. The proportions (expressed as % of whole image) of germ, vitreous and floury endosperm were determined from these images after principal component analysis was applied. Subsequent manual kernel dissection confirmed that the ratio of vitreous to floury endosperm was higher in kernels determined to be harder by NIR-HSI. The correlation coefficients between the manually obtained proportions (i.e. dissected) and proportions determined from NIR hyperspectral images (i.e. GU and GD images averaged) were 0.61, 0.59 and 0.11 for vitreous endosperm, floury endosperm and germ, respectively. The incongruence between the two types of determination reflects the surface-bias of reflectance spectroscopy. Irrespectively, NIR-HSI reflectance models could be developed without a reference method and applied to rapidly determine very hard from very soft kernels.

Automatic and rapid discrimination of cotton genotypes by near infrared spectroscopy and chemometrics.

This paper reports the application of near infrared (NIR) spectroscopy and pattern recognition methods to rapid and automatic discrimination of the genotypes (parent, transgenic, and parent-transgenic hybrid) of cotton plants. Diffuse reflectance NIR spectra of representative cotton seeds (n = 120) and leaves (n = 123) were measured in the range of 4000–12000 cm−1. A practical problem when developing classification models is the degradation and even breakdown of models caused by outliers. Considering the high-dimensional nature and uncertainty of potential spectral outliers, robust principal component analysis (rPCA) was applied to each separate sample group to detect and exclude outliers. The influence of different data preprocessing methods on model prediction performance was also investigated. The results demonstrate that rPCA can effectively detect outliers and maintain the efficiency of discriminant analysis. Moreover, the classification accuracy can be significantly improved by second-order derivative and standard normal variate (SNV). The best partial least squares discriminant analysis (PLSDA) models obtained total classification accuracy of 100% and 97.6% for seeds and leaves, respectively.

Rapid quantification of flavonoids in propolis and previous study for classification of propolis from different origins by using near infrared spectroscopy

A fast, simple and accurate near infrared spectroscopy (NIRs) method was investigated for the geographical origin discrimination and main flavonoid content determination of Chinese propolis. 180 propolis samples from four provinces of China were collected for establishing partial least squares (PLS) models of rutin, myricetin, quercetin, kaempferol, apigenin, izapinin, pinocembrin, chrysin, galangin and total flavonoids. The root mean square error of prediction (RMSEP) and correlation coefficient (R2) in the test set of the optimum models were 0.479 to 1.332% and 76.23 to 96.68%. The residual prediction deviation (RPD) values were all larger than 2.93. A paired t-test result showed that there was no significant difference between NIRs and HPLC methods at a 95% confidence interval. A principal component analysis (PCA)–Mahalanobis distance (MD) method was applied to classify the geographical origin of propolis samples, and 100% accuracy was obtained. Finally, a quality assessment was performed, and the propolis samples from Zhejiang and Liaoning province were classified as good quality. The developed NIRs method was a suitable tool for the rapid analysis of Chinese propolis, and might be also extended to the on-line quality control of propolis raw material in pharmaceutical industries, or monitoring industrial natural products extraction processes.

Analysis and identification of Chinese drugs by three-step infrared spectroscopy—A case study of Danshen

In this study, two types of Danshen from different growth years were discriminated and identified by a three-step infrared spectroscopy method (Fourier transform-infrared spectroscopy (FT-IR) coupled with second derivative infrared spectroscopy (SD-IR) and two dimensional correlation infrared spectroscopy (2D-IR)). Though only small differences were found in the FT-IR spectra of the samples, the positions and intensities of peaks at around 1635 and 1055 cm−1 could be considered as the key factors to discriminate them. More significant differences were exhibited in their SD-IR spectra, particularly the significant absorption bands attributed to polysaccharides and phenolic acids. The visual 2D-IR spectra provided dynamic chemical structure information of Danshen samples, which present different particular auto peak clusters in the range of 1000–1160 cm−1 and 1430–1700 cm−1, respectively. Furthermore, twenty different samples including ten of each herb were also successfully classified by soft independent modeling of class analogy (SIMCA). This study offers a promising method inherent with cost and time savings to characterize and control the quality of extremely similar and complicated herbal medicines like Danshen.

The role of dry and wet isothermal annealing treatment on the structure and the mechanical properties of isotactic polypropylene fibers

AbstractDry and wet annealing of isotactic polypropylene fibers was carried out under constant length at 120°C in air and in glycerine environments with annealing times ranging from 1 to 30 h. A detailed analysis of the infrared spectrum of samples annealed, especially in air, showed clear evidence of the surface oxidation as indicated by the appearance of oxygen containing functional groups. Annealing was found to lead to an improved structural organization as indicated by the crystallinity, crystallite size, and orientation measurements using X‐ray diffraction and infrared spectroscopy methods. Analysis of the X‐ray diffraction measurements showed a gradual transformation of metastable smectic phase to a more stable α‐monoclinic phase with increasing annealing time. Crystallinity, crystallite size, and orientation measurements performed for the samples annealed in air and in glycerine environments showed no distinct difference. Mechanical properties of the annealed samples were influenced by the annealing environment. Annealing in an air environment resulted in a continuous loss of tensile strength up to the annealing time of 12 h due to an oxidation related chain scission mechanism. On the other hand, annealing in glycerine environment resulted in a continuous and gradual increase of tensile strength without loss of physical form up to the annealing time of 30 h. It is suggested that wet annealing in glycerine environment should be used to obtain improved tensile strength values. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Fast analytical method on content and transfer rate of marker component in ethanol precipitation of cinobufacini by near infrared spectroscopy

The method of near infrared spectroscopy was established to analyze the content and transfer rate of the marker component, indole alkaloids, of cinobufacini in the process of ethanol precipitation. The samples of cinobufacini were collected, and the concentration of indole alkaloids was determined by the reference method, UV-vis spectroscopy. After the rejection of abnormal samples, the pretreatment of spectra and the choice of the corresponding wave band, the multivariate calibration models were established using PLS algorithm between spectra and the UV values. The samples in ethanol precipitation, which did not participate in modeling, were used to examine the performance of the models. The correlation coefficient of the calibration model was 0.9613. Root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) were 0.172 and 0.169, respectively. Furthermore, residual predictive deviation (RPD) of the model was 4.13, which meant quantity analysis was feasible. It is concluded that near infrared spectroscopy can be considered as a fast, effective and non-destructive analysis method applied in the process of ethanol precipitation for traditional Chinese medicine.

Method to Estimate Thermal Shrinkage Behavior of Glasses

We present a method to estimate the effect of heat treatment on the shrinkage behavior of glasses. As a pre‐requisite, sensitivity of the glass density as a function of glass fictive temperature is measured using the sink–float method and the slope of the relationship is used to determine the linear thermal strain proportionality factor. Evolution of the fictive temperature for different temperature–time history is measured using the infrared spectroscopy method and the results are used to estimate the structural relaxation parameters in the temperature range of interest. The overall shrinkage behavior is predicted using the linear thermal strain factor and estimated change in fictive temperature due to the thermal treatment. The predicted shrinkage behavior is observed to be in good agreement with the independent dimensional change measurements performed on large glass sheets that have undergone similar thermal treatments.

Studying the forms of dissolution of hydrogen, carbon, nitrogen and oxygen volatiles in magmatic melts of the early earth's mantle by the methods of IR and Raman spectroscopy

Citation: Kadik, A. A., V. V. Koltashev, E. B. Kryukova, V. G. Plotnichenko (2011), Studying the forms of dissolution of hydrogen, carbon, nitrogen and oxygen volatiles in magmatic melts of the early earth's mantle by the methods of IR and Raman spectroscopy, Vestn. Otd. nauk Zemle, 3, NZ6031, doi:10.2205/2011NZ000161. Experimental studies of the features of dissolution of Н, C, N, O volatiles in the melting products of the early Earth’s mantle are continued. As a model system we have chosen the aluminosilicate melt (albite NaAlSi3O8 80 wt. %) + metallic Fe phase (FeO 20 wt. %) + H+C+N with nitrogen addition (Si3N4 1, 3, 5, 7 wt. %) which at quenching the products of experiments provides НС-N-O-containing silicate glasses. The quenching was carried out at a high pressure 4 GPa, high temperature 1550 о С, and low values of the chemical oxygen potential (fugacity fO2) from -2 to -4 below the iron-wustite buffer equilibrium lgfO2 (IW). The investigation techniques were IR (infrared) micro spectroscopy and micro Raman. The IR absorption spectra (Fig. 1) were measured on a vacuum Fourier-transform FTIR spectrometer “Bruker IFS-113v” with an optical microscope “IR Microscope A590”, focusing the radiation passing through the investigated samples into a spot from 15 to 400 m in diameter. The Raman spectra measurements (Fig. 2) were provided on a Triple Raman spectrograph Т-64000 (Jobin Yvon) in which the exciting radiation from Ar + -laser was focused on a sample surface into a 2 m spot. The application of these techniques has allowed to establish the influence oxygen fugacity (fO2) on the ratio between the oxidized (H2O, OH - CO2, C=O, CO3 2- ) and reduced (H2, CH4, SiC, C-C) Н- and C-species in the melts, as well as O2, N2, N-O, C-N and others N-H complexes (NH3, NH4 + , NH2 - (≡Si-NH2), NH2 + (≡Si-O-NH2)) in a rather wide region of the redox state

Investigation of a rheo-optical method for determining the in-situ molecular orientation behavior in stretching films under biaxial deformation

We have developed a novel polarized infrared spectroscopy method for estimating the in-situ molecular orientation during the stretching of films under uniaxial and biaxial deformation. Isotactic polypropylene films were deformed at 110−160 °C in biaxial stretching mode. This method enabled us to provide the orientation functions of the crystalline and amorphous regions obtained from the dichroic infrared ratios as a function of strain or elongation time. The behavior of the orientation function was found to be almost independent of the stretching temperature, and the dominant factor for determining the chain orientation state was the strain rather than the stress.

Studies on the influence of different fly ashes and Portland cement on early hydration of calcium aluminate cement

The influence of three mineral additives, i.e. fly ashes from pulverized combustion and from fluidized combustion of hard coal as well as Portland cement, on early hydration (up to 28th day) of calcium aluminate cement was investigated. Cement pastes containing 0, 5 and 25 wt% of additives were studied by the use of calorimetry, thermal analysis and infrared spectroscopy methods. It was confirmed that hydration of calcium aluminate cement is closely dependent on the type of addition and its amount. The influence of additives of different properties on cement hydration was discussed basing on received results and other literature reports.