Non-destructive Spectroscopic Techniques Research Articles

Hats Off to Modeling! Profiling Early Synthetic Dyes on Historic Woolen Samples with ATR-FTIR Spectroscopy and Multivariate Curve Resolution-Alternating Least Square Algorithm.

This research focuses on analyzing wool samples dyed with synthetic dyes from the early 20th century. A methodology to identify and distinguish wool fibers dyed with azo, triphenylmethane, and xanthene dyes, which are no longer in use, using the ATR-FTIR spectra, is presented. Firstly, the dataset was subjected to PCA, which revealed the similarities and differences among the samples, illustrating a distribution pattern based on dye classes. MCR-ALS was employed to extract the spectral profiles of the dyed fibers, thereby enhancing the efficacy of the analytical techniques and extracting the comprehensive information from a single instrument. The combination of ATR-FTIR spectroscopy with chemometric methods, such as PCA and MCR-ALS, has proven to be an effective strategy for identifying and differentiating wool fibers dyed with early azo, triphenylmethane, and xanthene dyes. This approach has demonstrated particular effectiveness in enabling rapid analysis without requiring sampling or pretreatment. Moreover, the analysis is supported by thorough bibliographic research on these no longer used colorants. In order to maximize the potential of non-destructive spectroscopic techniques, such as ATR-FTIR, the approach used has proven to be crucial. This study underscores how chemometric techniques expand the capabilities of spectroscopy, extracting extensive information from a single instrument and aligning with the goals of cultural heritage analysis.

The Roman villa at the Castle of Baia (Naples, Italy): investigations on the polychromy of frescoed surfaces by using non-destructive spectroscopic techniques

During the Roman age, the southern promontory of the gulf of Baia was the perfect location for the construction of villae maritimae for the Roman élite that decided to spend their summer residences by the sea.One of these residences is now located in the military fortress of the Castello Aragonese di Baia, built in 1495 CE during the Aragonese period (15th century). Here, during restoration works, the ruins of the residential sector of the villa, which historical sources ascribe to Caesar, were unearthed. The most representative evidence of this is the outstanding in situ remain of mosaics, decorated plasters and finely frescoed surfaces decorated according to the repertoire of the II style. This research aims to investigate the polychromy of a wall decoration representing a perspective depiction of architectural scenes en trompe l'oeil analysed by means of a multi-analytical, non-destructive approach performed in situ. The combined use of spectroscopic techniques (portable X-ray fluorescence, Raman and Fourier Transform Infrared Spectroscopy) points out the use of a characteristic Roman palette, quantitatively assessed by colorimetric measurements. It consists of red and yellow ochre, calcite, hematite, organic black pigments, precious materials such as cinnabar and Egyptian blue, green copper compounds. Fourier Transform Infrared Spectroscopy also revealed the presence of synthetic resins, likely used for the conservation of mural paintings. These are, however, damaged by atmospheric humidity, as detected by Infrared Thermography. Gypsum has been identified as the main weathering product.

Chemical analysis of polymers used for 3D printing of firearms

3D-printed firearms cause challenges in criminal investigations and forensic analysis because they are difficult to trace. Indeed, in addition to being "ghost guns", they may not produce all the conventional ballistic traces normally used for firearm identification. However, 3D-printed firearms produce other very specific traces, such as polymer traces which come from the polymers used to print the firearm. To date, only a few studies have focused on the analysis of polymer traces. This study therefore aims to characterize polymer traces from 3D-printed firearms, using non-destructive spectroscopic techniques readily available in most forensic laboratories (i.e., FTIR and Raman) and evaluate the potential for association of polymer specimens or traces with their source. To do so, the study was divided into four parts. First, the population study conducted among 3D printing companies and individuals practicing 3D printing has revealed that PLA and PLA+ are the most widely used polymer types in Quebec, Canada. Second, FTIR and Raman spectroscopic analysis of polymer samples collected during the population study has allowed the development of a reference polymer spectral database. The analysis and interpretation of these spectra revealed that polymer filaments present very low intravariability, but very high intervariability, due in part to the different polymer types and the pigments used to color them. The use of chemometric tools with the spectra showed that these two spectroscopic methods were highly discriminating. Third, test firing of 3D-printed firearms has allowed for the simulation of a scene involving this type of firearm and the collection of polymer traces generated. Fourth, the comparison of chemical signatures between polymer filaments and polymer traces has allowed for the evaluation of the potential for chemical association. This study highlights the added value of chemical analysis of 3D-printed firearms polymer traces in a criminal investigation by demonstrating that polymer filaments, the polymer from which a 3D-printed firearm is made, as well as polymer traces generated during firing, can be linked chemically and provide relevant information.

Raman spectroscopy combined with multivariate statistical algorithms for the simultaneous screening of cervical and breast cancers.

Breast and cervical cancers are becoming the leading causes of death among women worldwide, but current diagnostic methods have many drawbacks, such as being time-consuming and high cost. Raman spectroscopy, as a rapid, reliable, and non-destructive spectroscopic detection technique, has achieved many breakthrough results in the screening and prognosis of various cancer tumors. Therefore, in this study, Raman spectroscopy technology was used to diagnose breast cancer and cervical cancer. A total of 225 spectra were recorded from 87 patients with cervical cancer, 60 patients with breast cancer, and 78 healthy individuals. The obvious difference in Raman spectrum between the three groups was mainly shown at 809cm-1 (tyrosine), 958cm-1 (carotenoid), 1004cm-1 (phenylalanine), 1154cm-1 (β-carotene), 1267cm-1 (Amide III), 1445cm-1 (phospholipids), 1515cm-1 (β-carotene), and 1585cm-1 (C = C olefinic stretch). We used one-way analysis of variance for these peaks and demonstrated that they were significantly different. Then, we combined the detected Raman spectra with multivariate statistical calculations using the principal component analysis-linear discrimination algorithm (PCA-LDA) to discriminate between the three groups of collected serum samples. The diagnostic results showed that the model's accuracy, precision, recall, and F1 score of the model were 92.90%, 92.62%, 92.10%, and 92.36%, respectively. These results suggest that Raman spectroscopy can achieve ultra-sensitive detection of serum, and the developed diagnostic models have great potential for the prognosis and simultaneous screening of cervical and breast cancers.

Variational Mode Decomposition for Raman Spectral Denoising.

As a fast and non-destructive spectroscopic analysis technique, Raman spectroscopy has been widely applied in chemistry. However, noise is usually unavoidable in Raman spectra. Hence, denoising is an important step before Raman spectral analysis. A novel spectral denoising method based on variational mode decomposition (VMD) was introduced to solve the above problem. The spectrum is decomposed into a series of modes (uk) by VMD. Then, the high-frequency noise modes are removed and the remaining modes are reconstructed to obtain the denoised spectrum. The proposed method was verified by two artificial noised signals and two Raman spectra of inorganic materials, i.e., MnCo ISAs/CN and Fe-NCNT. For comparison, empirical mode decomposition (EMD), Savitzky-Golay (SG) smoothing, and discrete wavelet transformation (DWT) are also investigated. At the same time, signal-to-noise ratio (SNR) was introduced as evaluation indicators to verify the performance of the proposed method. The results show that compared with EMD, VMD can significantly improve mode mixing and the endpoint effect. Moreover, the Raman spectrum by VMD denoising is more excellent than that of EMD, SG smoothing and DWT in terms of visualization and SNR. For the small sharp peaks, some information is lost after denoising by EMD, SG smoothing, DWT and VMD while VMD loses fewest information. Therefore, VMD may be an alternative method for Raman spectral denoising.

Material Characterization of Mayapán’s Effigy Censers’ Sherds

Ceramic production from ancient Mesoamerican civilizations is related with cultural and technological evolution processes. Studying ritual objects also provides information on ancient traditions and allows researchers to determine the importance of certain materials employed in its manufacture. In this work, a set of 72 of Mayapán’s effigy censers’ sherds was analyzed in situ by using a combination of non-invasive, non-destructive spectroscopic and imaging techniques for material characterization; colorimetry established an initial classification of the pigments present in the objects, XRF provided elemental information, FORS allowed us to describe the molecular characteristics, and hyperspectral imaging established compositional contrasts or similitudes between large regions of the different objects. Pigments were characterized, allowing us to describe the materials used in the decorations of such ritual objects. The pottery matrix was also characterized, leading to a detailed description of the clays and mixtures of minerals employed in the construction of the effigy censers.

Elucidating the nonproductive adsorption mechanism of cellulase with lignin fractions from hydrothermally pretreated poplar using multi-dimensional spectroscopic technologies

A multi-dimensional nondestructive spectroscopic technique is proposed to analyze the influence of pretreatment lignin distribution on subsequent enzymatic hydrolysis and build a “lignin structure-cellulase interaction” relationship.

Origin of Blue-Water Jadeite Jades from Myanmar and Guatemala: Differentiation by Non-Destructive Spectroscopic Techniques

Identifying the origin of jadeite jades has become increasingly important from both mineral resource and metamorphic geology perspectives. In this study, we differentiate Myanmar gem-quality blue-water jadeite jades from their Guatemala counterparts via integrating various non-destructive spectrographic techniques, including X-ray fluorescence (XRF), Ultraviolet-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. Our results show that the Myanmar blue-water jadeite jades are structurally homogenous with very few impurities, while their Guatemala counterparts commonly have a yellowish margin with scattered white albite and disseminated greenish inclusions of omphacite and (minor) aegirine-augite. Geochemically, the UV absorption spectral data indicate that the Guatemala samples have higher total Fe and Fe2+ contents, but lower Fe3+ content than the Myanmar samples. The Guatemala samples also have higher omphacite content (lower molar Na/(Na+Ca) ratio, as reflected by the lower IR absorption peak wavenumber) and higher heterogeneity (as reflected by the ~680 cm−1 Raman peak shift difference) than that from Myanmar. Major differences are also discovered in the blue series (Myanmar: 0–0.7 cm−1; Guatemala: 1.7–3.2 cm−1) and blue-green series (Myanmar: 6.9 cm−1; Guatemala 13.7 cm−1) of the Raman peak shift difference, which altogether can provide a novel, nondestructive method for distinguishing blue-water jadeite jades from different origins.

Evaluation of prediction of indigestible fiber fraction (iNDF) of whole-crop barley silage by using non-destructive spectroscopic techniques as a fast-screening method: comparison between FTIR vs. NIR

The objective of this study was to reveal the potential of using Fourier transform mid-infrared (FTIR) and near infrared (NIR) spectroscopy as tools for the determination of indigestible neutral (NDF) fraction (iNDF) of whole-crop barley silage. A total of 48 whole-crop barley silage samples collected from 48 different farms in Western Canada were analyzed for iNDF. Reference values were matched with NIR and FTIR spectra. Spectral data processing (pretreatments) included first derivative, standard normal variate, multiplicative scattering correction, second derivative, and orthogonal signal correction. Prediction equations were obtained from each model using an external validation set. The coefficient of determination for the external validation of iNDF was 0.62 for FTIR and 0.41 for NIR, while the corresponding ratio performance deviation was 1.69 and 1.38 for FTIR and NIR, respectively. Results from this research showed the high potential of applying infrared molecular spectroscopy for the examination of forage plant fiber digestibility. More studies are needed to improve the accuracy and performance of FTIR and NIR spectroscopies in predicting the iNDF of whole-crop barley silage samples.

Geochemical Characterization of the NWA 11273 Lunar Meteorite Using Nondestructive Analytical Techniques: Original, Shocked, and Alteration Mineral Phases.

A lunar feldspathic breccia meteorite, the Northwest Africa (NWA) 11273, was analyzed to compensate the lack of scientific data available about its mineralogy and geochemistry. In order to obtain a deeper characterization of the sample, a strategy based on the combination of nondestructive spectroscopic techniques such as X-ray fluorescence and Raman spectroscopy is used. Both techniques are being used in spatial missions by the Perseverance Rover, so their combination in the laboratory is here proposed as an optimal strategy to study the complete mineralogy of the sample. In addition to finding the minerals indicated by the Meteoritical Society (anorthite, olivine, pyroxene, kamacite, and troilite), other minor minerals were identified, such as zircon and ilmenite, which are minerals related to the Moon geology, as well as calcite and sulfate which can be considered products of terrestrial weathering. Finally, secondary minerals related to alteration processes were also found, such as hematite, quartz, and anatase. In this work, the alteration processes that gave rise to the detected secondary minerals have been proposed.

Spectroscopic characterization of xx century mural paintings of punta begoña’s galleries under conservation works

A multi-analytical approach based on the combined use of non-destructive spectroscopic techniques and micro-destructive techniques is presented, not only to characterize the mural paintings of Punta Begoña galleries (Getxo, Biscay, Spain), but also to fill the gaps found in the historical documentation. The galleries were built in 1918 for Horacio Echevarrieta, a spanish republican businessman, and are in the list of protected historical buildings of the Basque Country. The whole building is composed by two galleries and a main hall with francoist iconographies in their walls, which disagree with the owner’s ideology, painted around 1938 after the occupation of the building in the Spanish Civil War. There is a lack of historical information about the original aspect of the mural paintings (1918 decoration) or the nature of the observable paintings (1938 over paintings). Thanks to the analysis carried out by optical microscopy, Raman spectroscopy, X-ray fluorescence (XRF), Fourier Transform Infrared spectroscopy (FTIR), Scanning electron microscopy coupled to electron scattering X-ray spectroscopy (SEM-EDS) and X-ray diffraction analysis (XRD), it was possible to identify under the painted layers a lead white preparation layer. Then, the original mural pigments were identified being of a silicate nature due to the systematic presence of presence of Clinochlore in all the colours. Regarding the over painted panels, their characterization revealed pigments that did not fit with the contemporaneous pigments, common practice in the francoism regime. In addition, carnauba wax could be identified as the binder. Moreover, the main decaying pathways of the materials were pointed out. These results will help to provide a new vision of these mural paintings, and the whole building. However, the most important achievement was the historical contextualisation of the main hall, which could help to change the historical perception of this heritage, putting the analytical chemistry at the service of history.

Investigation of the Thermal Aging Behavior of Pyrotechnic Tracer Composition by Spectroscopic Techniques Coupled with Principal Component Analysis

AbstractThis work aims to investigate the aging behavior related to heat of a pyrotechnic tracer composition (PTC) sample composed of strontium nitrate as an oxidizer and dual‐fuel of Mg and Mg−Al alloy. Fresh and thermally aged samples were examined using nondestructive spectroscopic techniques, namely Raman spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray diffraction (XRD). The obtained results showed that aging for 20, 40, and 60 days at 65 °C does not provoke noticeable chemical or structural changes, whereas, after 60 days, the changes are visible, and become more obvious after aging for 120 days. These changes are caused by the partial decomposition of strontium nitrate and the oxidation of magnesium, which are followed by the generation of degradation products such as Sr(NO2)2, MgO, and Mg(OH)2. On the other hand, the applicability of FTIR and XRD associated with a chemometric tool, the principal component analysis, as a simple and useful technique has been also assessed to discriminate the spectra of the aged samples. It has been revealed that these combined approaches can be effectively used to recognize the main compositional and structural changes within the pyrotechnic tracer composition affected by the thermal degradation process.

Non-Destructive Spectroscopic and Imaging Techniques for the Detection of Processed Meat Fraud.

In recent years, meat authenticity awareness has increased and, in the fight to combat meat fraud, various analytical methods have been proposed and subsequently evaluated. Although these methods have shown the potential to detect low levels of adulteration with high reliability, they are destructive, time-consuming, labour-intensive, and expensive. Therefore, rendering them inappropriate for rapid analysis and early detection, particularly under the fast-paced production and processing environment of the meat industry. However, modern analytical methods could improve this process as the food industry moves towards methods that are non-destructive, non-invasive, simple, and on-line. This review investigates the feasibility of different non-destructive techniques used for processed meat authentication which could provide the meat industry with reliable and accurate real-time monitoring, in the near future.

Phytochemical Screening of the Different Cultivars of Ixora Flowers by Non-Destructive, Label-Free, and Rapid Spectroscopic Techniques

Ixora flowers of different cultivars are widely grown for their esthetic values as they have bright, abundant, and beautiful inflorescence. A derivative of plant origin, especially flowers, possesses a broad spectrum of biological activities; therefore, it is important to explore current techniques and protocols for the isolation, identification, and characterization of these substances. This study explores the utility of nondestructive spectroscopic probes for monitoring the composition and bioprocess in ixora flowers. The various cultivars of ixora flowers having dark red, dark pink, light pink, peach, orange, and yellow flowers have been collected, and their absorption, fluorescence, and scattering spectral signatures have been acquired using ultraviolet-visible, laser-induced fluorescence and confocal micro Raman spectroscopy. The pre-processing and spectral analysis reveal that biochemicals present in dark red, dark pink, light pink, orange, and peach ixora flowers include flavonoids, phenolic compounds, anthocyanins, and carotenoids of varying concentrations, while the yellow flowers are abundant in carotenoids. The spectral signatures obtained in this study open new avenues for monitoring the substances of plant origin in a nondestructive, rapid, robust, and sensitive way without high operational costs.

Raman spectroscopy for discriminating transgenic corns

Discrimination of genetically modified organisms is increasingly required by legislation and consumers worldwide. Currently the most commonly used detection methods for identification of transgenic crops are high cost, destructive and time-consuming, so not suitable for fast and extensive application. Raman is a noninvasive and nondestructive spectroscopic technique capable of extracting sample fingerprints. In this paper, Raman spectroscopy and chemometric tools were evaluated for discrimination of transgenic corn. Different spectral preprocessing as well as algorithms for variables selection were evaluated to fit a classifier model based on linear discriminant analysis (LDA). Results showed spectral bands assigned to carbohydrates and carotenoids responsible for classes discrimination. The best classifier achieved 87.5 % of predictive accuracy. These results suggest that genetic differences between evaluated classes are also expressed in their chemical composition, which could be detected using Raman spectroscopy. The developed method is clean, fast and can contribute for establishing normative about genetically modified foods.

Applicability of X-ray fluorescence spectrometry for assessing geochemical features and heavy metal contamination of soils: primary data

ABSTRACT X-ray fluorescence spectrometry (XRF) has long been considered a convenient and powerful method for the determination of trace amounts of chemical elements in various types of natural materials. XRF is rapid, reliable, and non-destructive spectroscopic technique, allows performing a direct analysis of solid samples without pretreatment. For the present report, we take advantage of the multielemental capability of the XRF-technique for the determination of major and trace amounts of rock-forming (Stot, Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, Fe2O3(tot)) and trace (F, V, Cr, Co, Ni, Cu, Zn, Ga, Pb, Rb, Sr, Y, Zr, Nb, Ba, La, Ce, Nd) elements in environmental solid samples. Nowadays, study of the soil cover exposed by human-caused impact is an important aspect in understanding the geochemical processes occurring in it. Study object is the biggest territory of the Baikal region named Olkhon, which is a natural area of preferential protection of federal significance and a part of the Baikal National Park. In this study, we have determined chemical composition of the soil upper horizon (~0–15 cm) of meadow-stepper landscapes of the Baikal region (the Olkhon Island) to reveal their geochemical features and heavy metal pollution level. Three varieties of the steppe soils were distinguished: middle loamy, light loamy and sandy loam. For the first time, the influence of soil granulometric features on the content level of the rock-forming and toxic elements in them has been established. In addition, the primary data relating to the assessment of the soil heavy metal contamination have been presented.

Comparative studies of the optical absorption coefficient spectra in the implanted layers in silicon with the use of nondestructive spectroscopic techniques

Comparative studies of the optical absorption coefficient spectra in the implanted layers in silicon with the use of nondestructive spectroscopic techniques

Partial amorphization of experimentally shocked plagioclase: A spectroscopic study

AbstractShock amorphization of plagioclase, from partial to complete, has been used to evaluate the degree of shock in meteorites. Important information on the shock amplitude can be derived from the measurement of the refractive index in plagioclase, either from mineral separates or in petrographic thin sections. However, this technique is time‐consuming, and associated sample preparations are considered destructive and are not always possible for precious and rare meteorite samples. In addition, plagioclase amorphization is commonly inhomogeneous at the sample scale and a statistically meaningful number of grains must be considered. Here, we apply several nondestructive spectroscopic techniques, such as Raman spectroscopy, photoluminescence, and cathodoluminescence, to plagioclase experimentally shocked at 28 GPa, and thus in the transition regime between crystalline plagioclase and fully amorphous material. Most of the plagioclase was transformed into diaplectic glass at 28 GPa, yet some grains exhibit heterogeneously distributed crystalline domains. This confirms that intrinsic and extrinsic factors lead to local variations in the intensity of the shock pressure within individual plagioclase crystals of homogeneous composition. The amorphization of plagioclase can qualitatively (and potentially also quantitatively) be investigated by spectroscopic techniques, highlighting such local variations in the shock efficiency.

Optical scattering field imaging along a nanofiber in operando

We present a non-destructive and non-invasive imaging spectroscopic technique with a high spatial and spectral resolution based on the detection of the Rayleigh scattering field radiated out of a centimetric length and micrometric size optical waveguide in operation.

Assessment of non-destructive spectroscopy and chemometrics tools for the development of green analytical methods to determine the shelf-life of olive oils

The development of sustainable and environmentally friendly analytical methods for agri-food products and the modification of reference methods is an essential issue to be treated in green analytical chemistry. The potential application of non-destructive spectroscopic techniques with chemometrics tools to achieve these principles are examined in this work. In this study a new sustainable analytical approach based on the use of fluorescence spectroscopy and multivariate analysis methods of Machine-Learning(Support Vector Machine regression) and chemometrics (Partial Least Square regression) have been developed to control the quality of virgin olive oils in Morocco according to their shelf life. The spectral data of 45 samples were first analyzed by principal component analysis method (PCA), the PCA method shows an important classification of the three groups of olive oil according to their shelf life. The use of the regression methods SVM and PLS shows a high ability to predict the quality of olive oils, this ability is shown by the high value of R-square and the low value of root mean square error of calibration and crossvalidation (RMSEC, RMSECV), the validation of these models by cross-validation shows the potential of this sustainable analytical approach in the determination of the quality of virgin olive oils.