Applied SpectroscopyPub Date : 2026-06-01Epub Date: 2025-10-21DOI: 10.1177/00037028251392563
Sila Jin, Alexis Weber, Young Mee Jung, Igor K Lednev
{"title":"Two-Dimensional Correlation Spectroscopy Analysis of Bloodstain Aging Using Fluorescence Spectral Data.","authors":"Sila Jin, Alexis Weber, Young Mee Jung, Igor K Lednev","doi":"10.1177/00037028251392563","DOIUrl":"10.1177/00037028251392563","url":null,"abstract":"<p><p>Understanding the biochemical aging mechanisms of bloodstains is essential for developing reliable forensic methods to estimate the time since deposition (TSD). Although fluorescence spectroscopy is effective for tracking endogenous fluorophores such as tryptophan, nicotinamide adenine dinucleotide (NADH), and flavins, its utility is limited by spectral overlap and sample variability. In this study, we employed two-dimensional correlation spectroscopy (2D-COS) and 2D gradient mapping method to investigate the time-dependent fluorescence changes in bloodstains, gaining molecular-level insights into the aging process. 2D-COS uncovered hidden spectral components and revealed sequential molecular changes, especially in NADH- and flavin-associated bands. The 2D gradient maps further visualized these spectral trends quantitatively over 24 hours of aging. This study focuses on uncovering the biochemical mechanisms underlying bloodstain aging, probed by fluorescence spectroscopy. These findings deepen our fundamental understanding of ex vivo blood degradation and establish a foundation for more accurate and robust forensic applications.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"614-621"},"PeriodicalIF":2.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145342900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eshtar Aluauee, James Bounds, Alexandre Kolomenskii, Hans Schuessler, Liam Fernyhough
{"title":"High-Sensitivity Detection of Acetone in Human Breath Using Near-Infrared Continuous Wave Cavity Ring-Down Spectroscopy.","authors":"Eshtar Aluauee, James Bounds, Alexandre Kolomenskii, Hans Schuessler, Liam Fernyhough","doi":"10.1177/00037028261454394","DOIUrl":"10.1177/00037028261454394","url":null,"abstract":"<p><p>This study utilizes continuous wave cavity ring-down spectroscopy (CW-CRDS) at a wavelength approximately 1672 nm to detect acetone and methane in exhaled human breath. We employed a commercial distributed feedback diode laser (DFB), which delivered approximately 4 mW of power across a tuning range of 3.5 nm to measure acetone and methane concentrations in exhaled human breath. A detection limit of about 10.5 parts per billion (ppb) was demonstrated. Samples were collected from two distinct population locations, 23 individuals from Doha, Qatar, and 19 volunteers from College Station, Texas. The content of multiple gas mixture components was determined. The developed method for retroactive determination of the laser tuning eliminated the need for online wavelength determination. Simultaneous measurements of acetone and methane in exhaled breath can assist in diagnosing and monitoring diabetes and in assessing metabolic profiles of individuals using this noninvasive technique.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028261454394"},"PeriodicalIF":2.2,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148013179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Reducing Non-Linearity in Spectral Evaluation via a Modified Lorentz-Lorenz Relation.","authors":"Thomas G Mayerhöfer, Isao Noda, Jürgen Popp","doi":"10.1177/00037028261454699","DOIUrl":"10.1177/00037028261454699","url":null,"abstract":"<p><p>Quantitative infrared spectroscopy of liquids often assumes linear Beer-Lambert behavior, although local-field interactions and dipole-dipole coupling introduce intrinsic nonlinearities. We investigate whether a modified Lorentz-Lorenz relation, motivated by electromagnetic theory, can reduce these deviations and restore approximate linearity in binary mixtures. Using benzene-toluene and benzene-cyclohexane as model systems, we evaluate linearity through RMSE metrics, hybrid 2D-correlation analysis, asynchronous residual sums of squares, and complex-valued classical least squares (CLS) regression. While correlation-based measures provide qualitative insights, they fail to reliably identify optimal linearization parameters. In contrast, CLS in the Lorentz-Lorenz-transformed domain, particularly with systematic-error correction, yields clear minima and substantially improves prediction accuracy, reducing mean absolute errors by more than a factor of three relative to the Beer-Lambert domain. These results demonstrate that the modified Lorentz-Lorenz transformation provides a physics-informed chemometric domain in which spectral mixing becomes more linear. The approach suggests extending inverse least square regression, principal component regression, and partial least squares regression into this domain to further enhance quantitative mixture analysis.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028261454699"},"PeriodicalIF":2.2,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148013244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Paul D A Pudney, Adrian Voda, Kenneth S Lee, David Tiemessen, Christopher Marsh
{"title":"Structure Evolution in Hair Fibres During Strain and the Effect of Relative Humidity.","authors":"Paul D A Pudney, Adrian Voda, Kenneth S Lee, David Tiemessen, Christopher Marsh","doi":"10.1177/00037028261457150","DOIUrl":"10.1177/00037028261457150","url":null,"abstract":"<p><p>Hair is primarily composed of proteins, notably keratin and keratin-associated proteins (KAPs), forming a complex composite material with important structural functions in nature. Its mechanical behaviour is intricate and includes conformational changes, notably the transition of keratin from α-helix to β-sheet structures. However, the precise conditions under which this transition occurs during stress-strain experiments and the influence of humidity on this process remain unresolved. In this study we use two structurally sensitive methods, Raman spectroscopy and wide-angle X-ray scattering (WAXS), to study the changes in situ as a function of strain under controlled conditions of humidity. The results are analysed by two-dimensional correlation methods, two-dimensional correlation spectroscopy (2D-COS) and perturbation correlation moving window two-dimensional correlation spectroscopy (PCMW2D), which clearly relate molecular changes to the strain. The results show for the first time for both methods, that two main α-helix to β-sheet transitions are generally observed, and that these shifts in position with changing humidity. Also, these transitions go via a disordered state. It is concluded that water modifies the matrix of the hair, which then determines at what strain the intermediate filaments unfold. These results are discussed in terms of the present proposed models of hair mechanical behaviour.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028261457150"},"PeriodicalIF":2.2,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148013191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M Rashad Khan, S U Haq, Qamar Abbas, Riaz Khan, Ali Nadeem
{"title":"Improvement in the Sensitivity and Reproducibility of Laser-Induced Soil Plasma Produced in a Microwave Environment.","authors":"M Rashad Khan, S U Haq, Qamar Abbas, Riaz Khan, Ali Nadeem","doi":"10.1177/00037028261455373","DOIUrl":"10.1177/00037028261455373","url":null,"abstract":"<p><p>This study investigated the influence of microwave (MW) on signal enhancement, shot-to-shot repeatability of emission signals, and parameters of laser-induced plasma (LIP) of soil samples. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser working at its fundamental wavelength, with energy ranging from 40 to 260 mJ was utilized in conjunction with MW power varying from 400 to 1200 W to generate plasma. The plasma emissions were recorded and analyzed with a spectrometer (LIBS 2500 Plus, Ocean Optics) at varying detector gate delay (DGD) up to 5 µs. At optimized laser energy of 140 mJ and MW power of 1.2 kW, the emission signal intensities and the signal-to-noise ratio (SNR) were enhanced by up to seven-fold and nine-fold, respectively, compared to conventional LIBS. Furthermore, MW coupling with plasma significantly improved LIBS repeatability by reducing the relative standard deviation (RSD) of emission line intensities from 38% to 11% and from 18% to 4%, for Mg and Si, respectively. Additionally, the MW-assisted LIBS also decreased shot-to-shot fluctuations in plasma temperature (<i>T</i><sub>e</sub>) from 15% to 6%, and in electron density (<i>N</i><sub>e</sub>) from 14% to 7%. These improvements in sensitivity and stability due to MW-assisted LIBS pave the way for future quantitative analysis and the detection of trace elemental contaminants in soil at low concentration levels (e.g., ppm), which is a critical application in environmental monitoring.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028261455373"},"PeriodicalIF":2.2,"publicationDate":"2026-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148013177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Surface Morphology Analysis of Thin Films of Perfluoroalkanes Using Atomic Force Microscopy-Infrared (AFMIR) with Respect to Surface Phonon-Polariton Modes.","authors":"Takayuki Oka, Nobutaka Shioya, Takeshi Hasegawa","doi":"10.1177/00037028261450651","DOIUrl":"https://doi.org/10.1177/00037028261450651","url":null,"abstract":"<p><p>Although atomic force microscopy-infrared (AFM-IR) spectroscopy enables nanoscale infrared characterization, the dielectric origin of its spectral contrast, particularly the role of collective vibrational modes, remains incompletely understood. Here, we investigate the correlation between nanoscale infrared spectra and surface morphology using thin films of perfluorotetracosane (C<sub>2</sub><sub>4</sub>F<sub>5</sub><sub>0</sub>). By comparing low-temperature vapor-deposited films and their aged counterparts, we track aging-induced morphological evolution from lying-oriented sub-micrometer aggregates to standing-oriented crystalline grains. For discussing fine features in the nano-scale spectrum, infrared p-polarized multiple-angle incidence resolution spectroscopy (pMAIRS) is also employed as a macroscopic reference in advance. The pMAIRS analysis reveals pronounced longitudinal-transverse optical (LO-TO) splitting, which increases upon aging due to an enhanced Berreman-type longitudinal field contribution associated with surface flattening and improved crystallinity. Nanoscale AFM-IR measurements in a resonance-enhanced-mode with top-down illumination configuration demonstrate that the local spectral response is predominantly governed by the transverse optical (TO) dielectric function, while surface phonon-polariton (SPP) modes are strongly enhanced, reflecting localized electromagnetic field confinement at crystalline grains. Through rigorous cross-scale comparisons of macroscopic and nanoscale spectroscopy, this study has experimentally established the dominant TO-controlled contrast mechanism in top-down AFM-IR and revealed the characteristics of SPP-driven nanoscale spectra. These results demonstrate that AFM-IR is a powerful probe for investigating both the chemical identity of surface-active organic materials and nanoscale surface morphology.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028261450651"},"PeriodicalIF":2.2,"publicationDate":"2026-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147969913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Two-Trace Two-Dimensional Correlation Analysis for the Confirmation of Therapeutic Protein Identification and Evaluation of Extent of Glycosylation: A Rapid Method for Testing Critical Quality Attributes.","authors":"Belinda Pastrana, Sherly Nieves, Eduardo I Canto","doi":"10.1177/00037028261451288","DOIUrl":"10.1177/00037028261451288","url":null,"abstract":"<p><p>Therapeutic proteins are an effective and highly selective, yet complex class of drugs for the treatment of diseases to improve the quality of life of patients. Their manufacturability is subject to evaluation to ensure product quality, safety, and efficacy. To this end, a need exists within the biopharmaceutical industry for a streamlined platform method that allows end-to-end therapeutic protein comparability assessment of multiple critical quality attributes. The implementation of a single platform method would de-risk development and accelerate speed to market. Herein, a novel method for therapeutic protein identification has been proposed that can be used to monitor regulated drug products throughout their lifecycle. The innovative streamlined method evaluates the intact protein in its formulation conditions. This breakthrough technology comprises a quantum cascade laser microscope with a heated accessory, an innovative slide cell array with a fixed path-length that allows for experimental flexibility and quantitative analysis, and dedicated software. Two-trace two-dimensional correlation spectroscopy (2T2D) was proven useful for the determination of spectral differences between two samples. The weighted absorbance differences, defined using the correlation between the cross-peaks, can be used to determine substantial molecular information, including secondary structure, the extent of glycosylation, amino acid content, and solvent accessibility, which is directly related to the therapeutic protein's critical quality attributes. Four different comparability assessments are discussed to demonstrate the usefulness of the platform method for the confirmation of protein identification and the comprehensive evaluation of the extent of glycosylation.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028261451288"},"PeriodicalIF":2.2,"publicationDate":"2026-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147969945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Determination of the Blend Ratio of Styrene-Butadiene-Styrene (SBS)/Polyethylene (PE) and Polypropylene (PP)/PP Polymers Using a Portable Near-Infrared (NIR) Spectrometer Combined with the Classical Least Squares (CLS) Method.","authors":"Hideyuki Shinzawa, Shogo Yamane, Naoki Kanayama","doi":"10.1177/00037028261445431","DOIUrl":"https://doi.org/10.1177/00037028261445431","url":null,"abstract":"<p><p>This paper describes a method that can be utilized for pre-sorting in chemical recycling processes. Namely, the blend ratios of polymers are determined by employing a low-cost near-infrared (NIR) spectrometer and a spectral deconvolution technique called the classical least squares (CLS) method. The determination of the blend ratio of polymer blends by CLS assumes that the raw material composition of the post-consumer or post-industrial materials is often not completely unknown; rather, it is generally partially known or can be reasonably inferred thanks to prior knowledge of product specifications or manufacturing processes. In short, we can often use the pure component spectra of the constituents in the polymer samples. The NIR spectra effectively capture the structural features of styrene-butadiene-styrene (SBS)/polyethylene (PE) and polypropylene (PP)/PE blend samples, which are complicated by greatly overlapping peaks arising from the components. The near-infrared (NIR) spectra were then subjected to CLS to obtain so-called concentration profile, e.g., the blend ratio of the polymer constituents, by using pure component spectra of SBS, PE, and PP. The pure component spectra were successfully fitted to the observed NIR spectra of SBS/PE and PP/PE samples and estimated blend ratios were achieved with exceptionally high accuracy thus demonstrating that NIR spectroscopy can be a powerful tool for use in the pre-sorting process.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028261445431"},"PeriodicalIF":2.2,"publicationDate":"2026-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147947494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fourier Transform Infrared Photoacoustic Spectroscopy (FT-IR-PAS) Combined with Two-Trace Two-Dimensional Correlation (2T2D) Analysis for Studying Surface Changes in Poly(3-hydroxybutyrate-<i>co</i>-3-hydroxyhexanoate) (PHBH) Films Under Marine Microbial Degradation.","authors":"Naoki Kanayama, Kohei Hidaka, Mamiko Shimamura, Takamasa Miura, Noriko Takahara, Hideaki Hagihara, Hideyuki Shinzawa","doi":"10.1177/00037028261444737","DOIUrl":"https://doi.org/10.1177/00037028261444737","url":null,"abstract":"<p><p>This study demonstrates the use of Fourier transform infrared photoacoustic spectroscopy (FT-IR-PAS) to investigate surface structural changes in biodegradable poly(3-hydroxybutyrate-<i>co</i>-3-hydroxyhexanoate) (PHBH) films during marine microbial degradation. FT-IR-PAS, a non-contact and surface-sensitive technique, enables the analysis of brittle or rough surfaces without pretreatment and offers clear advantages over conventional attenuated total reflection infrared (ATR-IR) for degraded films. To enhance spectral interpretation, FT-IR-PAS was combined with two-trace two-dimensional (2T2D) correlation analysis, which allowed the detection of subtle spectral variations associated with microbial degradation. This approach revealed changes in the carbonyl stretching bands (1675-1775 cm<sup>-1</sup>) linked to the molecular order of the PHBH chains, enabling the detection of changes in the proportion of crystalline and amorphous regions on the surface. Asynchronous 2T2D correlation spectra for PHBH residues revealed specific cross-peaks at (1726 cm<sup>-1</sup>, 1743 cm<sup>-1</sup>), indicating preferential degradation of amorphous regions. Furthermore, the asynchronous correlation intensities at these positions showed a positive relationship with the PHBH film weight loss resulting from microbial degradation. These findings highlight FT-IR-PAS coupled with 2T2D analysis as a powerful, non-destructive approach for elucidating the surface degradation mechanisms of biodegradable polymers under marine conditions.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028261444737"},"PeriodicalIF":2.2,"publicationDate":"2026-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147940121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mingyue Huang, Hailong Feng, Jing Liang, Yu Xue, Xuan Xu, Xiaoxuan Xu, Bin Wang, Jing Xu
{"title":"Dual-Branch Multiscale Attention Network (DMANet): Integrating Dynamic Two-Dimensional Correlation Spectroscopy Using a Dual-Branch Multiscale Attention Network for Beef Adulteration.","authors":"Mingyue Huang, Hailong Feng, Jing Liang, Yu Xue, Xuan Xu, Xiaoxuan Xu, Bin Wang, Jing Xu","doi":"10.1177/00037028261438812","DOIUrl":"https://doi.org/10.1177/00037028261438812","url":null,"abstract":"<p><p>To address the detection of low-level duck meat adulteration in beef, this study proposes a method based on near-infrared (NIR) two-dimensional correlation spectroscopy (2D-COS) and a dual-branch multiscale attention network (DMANet), enabling semi-quantitative prediction of duck meat content. The approach expands one-dimensional (1D) NIR spectra into synchronous and asynchronous 2D-COS, constructing a dual-branch network that extracts complementary characteristics using multiscale convolution. An adaptive attention mechanism dynamically fuses the two spectral modalities, enhancing sensitivity to subtle adulteration traits. Experiments show the model achieves 100% overall accuracy on the test set, outperforming a traditional partial least squares (PLS) model (81.6%) and single-input models (94.6% for synchronous and 92.8% for asynchronous maps). In the 0.5-5% adulteration range, it improves accuracy by 31.3%, 12.5%, and 18.7% over these benchmarks, respectively. Notably, 2D-COS consistently surpasses 1D spectral models in detecting low-content adulteration by amplifying dynamic spectral responses and strengthening characteristics of trace contaminants.</p>","PeriodicalId":8253,"journal":{"name":"Applied Spectroscopy","volume":" ","pages":"37028261438812"},"PeriodicalIF":2.2,"publicationDate":"2026-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147832915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}