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Society for Applied Spectroscopy

@sasspectroscopy.bsky.social

www.s-a-s.org The Society for Applied Spectroscopy is a nonprofit organization formed to advance and disseminate knowledge and information concerning the art and science of spectroscopy.

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Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 8h ago

New from Applied Spectroscopy! Micro-#Raman #Spectroscopy, X-ray Fluorescence, and X-ray Diffraction Analysis of Materials, Stratigraphy, Hidden Inscriptions, and Artistic Techniques in Portrait of Farrokh Gaffari More: https://doi.org/10.1177/00037028261449272 #SAS #art #painting #XRD #XRF #Iranian

$Abstract: This study employs an integrated, multi-technique, minimally microinvasive investigation of the material composition, stratigraphy, and technique of the Portrait of Farrokh Gaffari, which was created in 1959 by Qollar-Aqasi, an artist of the Iranian Coffeehouse Painting workshop, thereby closing the element → phase → molecule evidence chain by combining whole-field macroscopic X-ray fluorescence analysis (MA-XRF) with X-ray diffraction (XRD) and micro-Raman, complemented by cross-section microscopy and fiber analysis. MA-XRF resolves two subsurface narratives: Continuous Sr and Ba-K line patterns that expose hidden Persian lettering on a reused shop-sign support (blue ground with white lettering), and an Fe-mapped pentimento masked by Fe-poor overpaint, documenting a localized compositional revision. Mapping and section analysis reveal a zinc-rich gray priming beneath the paint and multi-campaign varnishes. Using Bruker Gamma Filter technology, effective separation of substrate-derived and surface zinc signals was achieved, thereby improving the accuracy of spectral targeting. Raman identifies lithol red (PR49, likely PR49:2) as the principal red and Prussian blue (PB) as the main blue. Ultramarine occurs as deep-blue accents. XRD identifies lithopone (BaSO4+ZnS), zinc oxide (ZnO), and lead chromate (PbCrO4), rationalizing why the red is XRD-silent while whites/yellows are phase-visible. Together, these data resolve a compact, high-saturation palette logic: mixture-greens from PbCrO4 + PB, lithopone-moderated whites and reds, and area-specific combinations (e.g., canopy: PbCrO4 + PB + iron oxide + lithopone; fountains and flowing water: PB + lithopone, flowerbeds/red blossoms: lithol Red (PR49) + carbon black). Fiber microscopy identifies a cotton support assembled from two panels with orthogonal warp orientations. Furthermore, it is worth noting that this painting was executed on a repurposed blue-background-with-white-lettering advertising sign, which is a substrate choice that not only aligns closely with the pragmatic “local material adoption” principle of the Coffeehouse Painting workshop but also echoes their typical painting-on-a-sign practice, with the original sign’s material composition specified as follows: the blue ground comprises CaCO3, BaSO4, and PB, while the white lettering is formulated with BaSO4.$

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 2d ago

New from Applied Spectroscopy! Spectral Similarity Analysis of Camphor-10-Sulphonic Acid: A System Suitability Standard for Circular Dichroism in Quality Regulated Environments Read more: https://doi.org/10.1177/00037028261437102 #SAS #Spectroscopy #UV #Circular #Dichroism #CD

Abstract: Spectral similarity supports comparison of circular dichroism (CD) spectra by using all datapoints to improve alignment of wavelength, intensity and offset. CD is increasingly used to confirm the higher order structure and stability of biopharmaceutical proteins, which requires method validation and assessment of robustness in quality regulated analytical systems. Camphor-10-sulphonic acid (CSA), or its ammonium salt, is widely used to calibrate spectropolarimeters, with its use specified in the European Pharmacopoeia (EP), and, more broadly, as a system suitability standard. Spectral similarity comparison of 75 CSA reference spectra in the Protein Circular Dichroism Data Bank (PCDDB) showed the potential value of this approach to monitor instrument performance and support compliance within a quality system.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 5d ago

New from Applied Spectroscopy! Stacked Machine Learning for Timber Identification Using Laser-Induced Breakdown Spectroscopy (LIBS) Read more: https://doi.org/10.1177/00037028261444395 #SAS #Spectroscopy #LIBS #timber #ML #Dalbergia #SVM

Abstract: This study presents a new approach to wood species identification using laser-induced breakdown spectroscopy (LIBS) combined with stacked machine learning techniques. The research analyzed 700 samples comprising nine Dalbergia species and nine additional tropical timber species, utilizing a handheld LIBS analyzer. A stacking methodology was developed by integrating three support vector machine (SVM) models with different kernel functions (linear, polynomial, and radial) in a one-versus-all (OVA) configuration. These SVM outputs were then combined using a partial least squares discriminant analysis (PLS-DA) meta-learner. Through PCA-based variable selection, the dimensionality was reduced from 23 401 to wavelengths while maintaining classification accuracy. The stacking approach achieved a Cohen's kappa value of 0.8671 in the validation set, significantly outperforming traditional flat classifiers. Variable importance analysis revealed calcium, magnesium, and barium as crucial elements for species differentiation, with their concentrations reflecting environmental conditions and geographical origins. This research demonstrates the potential of combining LIBS spectroscopy with advanced machine learning techniques for rapid, non-invasive timber identification, which can support efforts against illegal logging and enforcement of international trade regulations.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 5d ago

Be sure your organization is part of the conversation year-round with a SAS sponsorship and advertising opportunities, which can help you connect with a highly engaged audience of scientists, researchers, and industry professionals from around the world.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · last wk.

☀️ Summer is a great time to explore new opportunities and plan your next career move. Whether you're looking for a position in academia, industry, or research, the SAS Career Postings page can help you discover what's next in spectroscopy and analytical science.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · last wk.

New from Applied Spectroscopy! Data Adequacy Testing for Partial Least Squares Discriminant Analysis Using Raman Spectra Read more: https://doi.org/10.1177/00037028261439686 #SAS #Spectroscopy #PLS #Raman #predictor #NullHypothesis

Abstract: Partial least squares discriminant analysis (PLS-DA) is often used for data sets that consist of a large number of potential predictors but relatively few observations such that chance correlations between predictors and response can occur that lead to false conclusions. Hence, there is a need for data adequacy testing before model building but currently no such method exists. In this work we propose one where we used random permutations to destroy the correlation structure between predictor and response data. This produced normal distributions of chance correlation coefficients that were used to find correlation coefficients in the non-permuted data that differed significantly from chance occurrences. Based on these distributions, we defined two novel null hypotheses to control for when a true null hypothesis is incorrectly rejected and the other for when a false null hypothesis is not rejected. To counter false positive errors, the standard significance levels were adjusted with predictor-based Bonferroni corrections. To counter false negative errors, we compared the true and permuted correlation coefficients in distribution tails. The outcomes of the hypothesis tests then indicated whether or not PLS-DA models could be successfully built from these data sets. We also investigated how to determine the number of samples needed for a data set with a given number of predictors. Simulations showed that our method produced significantly fewer false positives than PLS-DA (P = 0.0018, our method error rate 12 × less than PLS-DA error rate) but significantly more false negatives (P = 0.0003, our method error rate 4.5 × more than PLS-DA error rate). Data from Raman spectroscopy showed that the method transferred to real data. By pre-screening such data, our method can aid in assessing whether to proceed with model building and, when there is a need to increase the sample size, we show by how much.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · last wk.

New from Applied Spectroscopy! Quantitative Diagnostics of Hydroxyl (OH) Radicals in Methane–Air Flames Using Wavelength Modulation Spectroscopy with Correction for Water Spectral Interference Read more: https://doi.org/10.1177/00037028261450621 #SAS #Spectroscopy #WMS #NIR #DAS #flame

Abstract: Exhaust gases generated by fossil fuel combustion significantly contribute to air pollution and climate change, emphasizing the need for efficient combustion diagnostics. OH radicals are key indicators of flame behavior; however, conventional laser-induced fluorescence (LIF) techniques are impractical for industrial monitoring due to their complexity. In this study, wavelength modulation spectroscopy (WMS) employing a near-infrared laser at 1.49 μm was used to measure OH radical concentrations, incorporating a correction for spectral interference from H2O. A wavelength division multiplexer (WDM) was used to enable the simultaneous operation of two lasers at 1.49 μm (OH) and 1.39 μm (H2O, temperature), allowing for correction of water interference. OH concentrations were determined using both WMS and direct absorption spectroscopy (DAS), and the results were evaluated through comparison with CHEMKIN simulations. The proposed dual-laser system demonstrated reliable and interference-corrected quantification of OH radicals in methane (CH4)/air premixed flames over a range of equivalence ratios. Comparisons with thermocouple-based temperature measurements and CHEMKIN-predicted species concentrations confirmed the reliability of the proposed technique. This study highlights the robustness and applicability of WMS-based OH diagnostics for combustion monitoring and demonstrates the potential for future implementation in industrial burner systems.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · last wk.

🌟 SciX 2026 Keynote Spotlight: Professor Jennifer Dionne SciX attendees won't want to miss “Exploring Light and Life: Nanophotonics and AI for Molecular Sequencing and Single-Cell Phenotyping,” presented by Professor Jennifer Dionne of Stanford University.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 2w ago

📣CALL FOR PAPERS📣: @applspecpractica.bsky.social will publish a collection titled Advancing Analytical Methodologies for Complex Pollutants: #PFAS and #Microplastics. The submission deadline is September 1, 2026. Learn more: https://loom.ly/Rj_AQGM

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 2w ago

New from Applied Spectroscopy! Biological and Biomedical Applications of Optical Photothermal Infrared Spectroscopy (O-PTIR) Read more: https://loom.ly/taQDbOE #SAS #Spectroscopy #OPTIR #infrared #Raman #review #history #microscopy

Abstract: Optical photothermal infrared (O-PTIR) spectroscopy is rapidly transforming molecular imaging by combining the chemical specificity of infrared absorption with the high spatial resolution enabled by visible-light excitation. This review provides a comprehensive and forward-looking overview of O-PTIR, with a particular focus on its expanding applications in biological and biomedical research. We begin by outlining the development of O-PTIR from earlier photoacoustic and photothermal infrared methodologies, placing it within the broader field of vibrational spectroscopy and emphasizing its unique advantages including sub-micrometer spatial resolution, label-free detection, and compatibility with heterogeneous biological samples. The foundational principles of O-PTIR, such as the photothermal effect, instrumental configurations, and the integration of simultaneous IR and Raman measurements, are discussed to establish the basis for its analytical capabilities. Leveraging these strengths, O-PTIR enables high-resolution and chemically specific imaging of key biomolecules including lipids, proteins, nucleic acids, and metabolites across cells, tissues, and microbial systems. Current applications span diverse areas such as cellular metabolism, microbial phenotyping, cancer diagnostics, biomarker identification, and pharmaceutical analysis. Alongside these advances, we critically evaluate existing limitations, including challenges associated with sample preparation, instrumental complexity, signal interpretation, and standardization. Finally, we highlight emerging directions such as live-cell O-PTIR measurements, artificial intelligence (AI)-driven spectral analysis, and the development of hybrid modalities including FISH-O-PTIR. Together, these innovations reinforce O-PTIR's potential as a transformative technology for biological and biomedical sciences, poised to bridge fundamental molecular studies with future clinical and translational applications.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 2w ago

☀️ Summer is a great time to catch up on the latest from SAS! Make sure your email address is up to date in your member profile so you don't miss important news, upcoming events, educational opportunities, and the SAS Newsletter.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 2w ago

✈️ Looking to travel this summer? Why not add a spectroscopy conference to your itinerary? Join colleagues from around the world at the International Conference on Raman Spectroscopy (ICORS 2026), taking place August 23–28, 2026 in Istanbul, Turkey.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 2w ago

New from Applied Spectroscopy! Two-Trace Two-Dimensional (2T2D) Correlation Spectroscopy of Lymphocytes in Infectious Mononucleosis Read more: https://doi.org/10.1177/00037028261449822 #SAS #Spectroscopy #Raman #2DCOS #2T2D #EBV #diagnosis #Lymphocytes

Abstract: Raman spectroscopy has been widely demonstrated as a powerful tool for analyzing macromolecules characteristic of living organisms. This research focuses on a detailed spectroscopic analysis of lymphocytes affected by infectious mononucleosis caused by Epstein–Barr virus (EBV, HHV-4). As shown, at least 98% of the population is infected with EBV, making it one of the most common viruses. The main aim of this study is to evaluate the capability of Raman spectroscopy to distinguish between healthy lymphocytes from those infected with EBV at an early stage of infection. Blood samples were collected from patients with infectious mononucleosis who were receiving treatment at the University Hospital in Kraków. For comparative purposes, samples from healthy volunteers were also included. To guarantee detailed analysis, Raman spectra were acquired using two excitation wavelengths: 514.5 nm and 785 nm. The two-trace two-dimensional (2T2D) correlation method was performed to recognize the difference between EBV-infected and healthy cells. Initially, mean Raman spectra were calculated for healthy and infected cells and subsequently used to generate synchronous and asynchronous 2T2D correlation maps. Analysis of the asynchronous correlation spectra reveals distinct differences between healthy and diseased lymphocytes for both excitation wavelengths. For example, asynchronous peaks at 514.5 nm excitation indicate the beginning of immunoglobulin formation, while at 785 nm excitation indicate Tyrosine phosphorylation, which corresponds to activation of lymphocytes. The detection of specific biochemical alterations shows the potential of Raman spectroscopy as a non-invasive diagnostic tool in viral infections.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 2w ago

Your hard work deserves to be recognized!

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 2w ago

New from Applied #Spectroscopy! Characterization of Additives in Polyvinyl Chloride Using #Infrared Spectroscopy and Evolved Gas Analysis–Mass Spectrometry Coupled with Two-Dimensional Correlation Spectroscopy Read more: https://doi.org/10.1177/00037028251398865 #SAS #mass #2DCOS #PVC #plasticizer

Abstract: Phthalate-based plasticizers in polyvinyl chloride (PVC) polymer were examined using infrared (IR) spectroscopy and evolved gas analysis–mass spectrometry (EGA-MS), a type of mass spectrometry (MS). IR signals arising from the C=O stretching vibrations of the plasticizers are observed but it is difficult to distinguish individual components due to their structural similarity. In contrast, temperature-dependent mass spectra of the PVC sample revealed a characteristic increase in total ion signals within the 100–220 °C range, indicating that plasticizer desorption occurs predominantly before decomposition of the PVC polymer. The application of two-dimensional correlation spectroscopy (2D-COS) to the mass spectra elucidated the detailed sequence of spectral changes during thermal desorption. The 2D correlation spectra derived from the mass spectra within the 100–220 °C range exhibited distinct correlation peaks associated with bis(2-ethylhexyl) phthalate, bis(2-ethylhexyl) adipate, and bis(2-ethylhexyl) sebacate. These results demonstrate that EGA-MS, combined with 2D-COS, can effectively identify individual additives in polymer systems.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 3w ago

🏆 Congratulations to Professor Kevin Wilkinson of the Université de Montréal, recipient of the 2026 Lester W. Strock Award!

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 3w ago

New from Applied Spectroscopy! Two-Dimensional (2D) Polarized Near-Infrared (NIR) Correlation Spectroscopy for Characterizing Reorientation of Low-Density Polyethylene (LDPE) Read more: https://doi.org/10.1177/00037028261426391 #SAS #Spectroscopy #NIR #2DCOS #LDPE #polarized #amorphous

Abstract: A polarized near-infrared (NIR) study for characterizing the orientation distribution of polymer chains is described. A low-density polyethylene (LDPE) sheet prepared with a hot rolling press is gradually rotated while being probed with a high-speed polarized NIR spectrometer based on an acousto-optic tunable filter (AOTF) to obtain a series of NIR spectra. During the change in the rotation angle, the spectral feature varies depending on the direction of the molecular vibration within the sample. The fine features of the spectral changes are readily analyzed with the two-trace two-dimensional (2T2D) correlation method by using the spectrum measured at 0° as a sample spectrum. The asynchronous correlation intensities between the crystalline and amorphous bands of the LDPE exhibited a sinusoidal variation depending on the selected reference spectrum (i.e., polarization angle). In particular, the intensities provide local maximum points at 90° and 270° where the direction of the polarized NIR light becomes parallel to the hot rolling direction. Consequently, the cyclic pattern of the asynchronous correlation intensity suggests that the hot rolling treatment substantially induces the reorientation of the polymer chains and subsequent additional crystallization, which makes the LDPE hard and brittle.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 3w ago

Whether you're new to spectroscopy or a seasoned professional, continuing education can help you stay current with emerging techniques, expand your expertise, and sharpen your skills. SAS offers a variety of educational and training opportunities designed for professionals at every career stage.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 3w ago

New from Applied #Spectroscopy! Combining Polarization Analysis and #Isothermal #Crystallization Behavior Elucidated by Two-Dimensional Correlation Spectroscopy for Understanding the Crystallization Properties of #PHBHx Read more: https://loom.ly/QKd0EnQ #SAS #2DCOS #Raman

Abstract: Poly(3-hydrxybutyrate-co-3-hydroxyhexanoate) (PHBHx) is a biopolymer that is produced and degraded by microbes. Because of the potential to replace polymers derived from petrochemicals with these materials, there is a high level of expectation for its commercial uses if its physical and chemical properties can be understood and controlled. Among other things these properties are determined by the polymer’s morphology – that is its crystallinity, and orientation of both crystalline and amorphous phases. The focus on the Raman characteristics of the crystalline phase enables elucidation of the characteristics of the polymer experiencing dynamic crystallization under various conditions. In this article we will start by reviewing the changes in the Raman spectrum from an amorphous to a crystalline material in an isothermal crystallization study. In that study a correlation field splitting between a CH stretching band that interacts with the carbonyl group on the opposite chain in the unit cell was identified. Then we will show the polarized Raman spectra of single crystals which enable an explanation of the residual amorphous material seen in the spectra of single crystals. Using the information from the single crystal measurements we can then study the Raman behavior of spherulites and confirm the model that proposes an explanation for the appearance of rings in the polarized light microscope (PLM) images of some spherulites. The polarized Raman studies confirm that the crystal ribbons that grow along the radii are twisting about the growth direction. The two-dimensional correlation spectroscopy (2D-COS) analysis of the polarized spectra of spherulites suggest the presence of strain that has been proposed to induce the twisting.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 3w ago

While summer is in full swing, soon the new school year will be starting. At SAS we'd love to see what students are interested in and what areas members are in to help forge connections. For students interested in spectroscopy, what area are you most interested in now?

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 3w ago

New from Applied Spectroscopy! Two-Dimensional Correlation Spectroscopy Analysis of Bloodstain Aging Using Fluorescence Spectral Data Read more: https://doi.org/10.1177/00037028251392563 #SAS #Spectroscopy #2DCOS #blood #fluorescence #NADH #flavin

Abstract: 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.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 4w ago

SAS encourages members voice their concerns about #OMB funding changes by the ❗ July 13th deadline❗. The OMB proposal can be found at https://loom.ly/WOwCQZk or https://loom.ly/ToR9Iio. Read the full statement from SAS regarding the proposed OMB changes here: https://loom.ly/jbyTFwk

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 4w ago

⏳ SciX 2026 is just 3 months away! Join the spectroscopy and analytical science community in Sparks, Nevada, from October 4 – 9, 2026, for a week of cutting-edge research, technical sessions, networking, and collaboration. 📅 Early Bird Registration ends August 14

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 4w ago

New from Applied Spectroscopy! Deviations from the Beer–Lambert Approximation Investigated Using Two-Dimensional Correlation Infrared Spectroscopy Read more: https://doi.org/10.1177/00037028251368394 #SAS #Spectroscopy #asynchronous #2DCOS #interference #Infrared

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 4w ago

🎥 Looking for a refresher on a spectroscopy topic or want to revisit a presentation you found valuable? SAS's webinar library is a great resource for staying current on developments in the field and expanding your knowledge at your own pace.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 4w ago

New from Applied Spectroscopy! Spectroscopic Study of Solution Crystallization of a Biodegradable Polyester Streamlined with a Correlation Filter (CF) Read more: https://doi.org/10.1177/00037028251370762 #SAS #Spectroscopy #2DCOS #bioplastic #PHBHx #2DCDS #correlation #filter

Abstract
Due to the growing interest in high-purity bioplastics for emerging applications, we investigated the solution crystallization of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHx) from a chloroform solution using advanced spectroscopic techniques. Compared to melt crystallization, solution crystallization proved to be a more complex process. Solvent evaporation led to the formation of amorphous PHBHx and less-ordered crystallites. Subsequently, a distinct intermediate species of slightly disordered crystals formed, eventually transforming into more ordered crystalline structures. To analyze the time-dependent attenuated total reflection infrared (ATR-IR) spectra during crystallization, we employed two-dimensional correlation spectroscopy (2D-COS) and codistribution spectroscopy (2D-CDS). To streamline the 2D analysis of this complex dynamic system, we utilized a correlation filter (CF) technique to attenuate interfering contributions from overlapping peaks.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 4w ago

An important update from SAS regarding the U.S. Office of Management and Budget: https://loom.ly/jbyTFwk

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · 4w ago

🏆 Congratulations to Jürgen Popp of the Leibniz Institute of Photonic Technology, recipient of the 2026 Ellis R. Lippincott Award!

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · last mo.

🎓 Summer is flying by, and the start of a new academic year will be here before you know it! Now is the perfect time for students to join SAS and start building connections within the spectroscopy community.

Society for Applied Spectroscopy @sasspectroscopy.bsky.social · last mo.

New from Applied Spectroscopy! Determination of Characteristic Bands and Correlation Filters for Two-Dimensional Correlation Spectroscopy (2D-COS) Read more: https://doi.org/10.1177/00037028261417374 #SAS #Spectroscopy #2DCOS #automated #filters

Abstract: Identifying characteristic bands, those exhibiting the most distinct features (i.e., minimal correlation among themselves), is a critical step in two-dimensional correlation spectroscopy (2D-COS) analysis. This process is essential for establishing effective correlation filters to simplify congested spectral datasets. Historically, such bands were selected using subjective methods, primarily the visual inspection of correlation cross-peaks. We now propose a more systematic and objective procedure based on the sequential multiplication of horizontal slices from a 2D discrimination spectrum. This unsupervised, automatic method is potentially integrable into model-free 2D-COS analyses, making it compatible with automated, machine-based interpretation.