Spectroscopy Top 10 Articles of the Month (August 2026)

Each article has been selected based on the number of successful DOI page views by readers as reported by [email protected]. The articles showcase key developments and insights in spectroscopy and chromatography. Spectroscopy covers the main topics of electronic spectroscopy, vibrational spectroscopy, magnetic resonance, imaging techniques, atomic spectroscopy, and data analysis and integration. LCGC covers most aspects of liquid and gas chromatography, mass spectrometry, and related technical aspects of separation science.

This month's ranking is dominated by Brian C. Smith's ongoing Infrared Spectroscopy of Polymers series, which claims five of the ten individually ranked spots, alongside continued reader interest in artificial intelligence, chemometric data handling, high performance liquid chromatography, and biopharmaceutical characterization from Spectroscopy and LCGC International.

1. Infrared Spectroscopy of Polymers XIII: Polyurethanes

Author: Brian C. Smith

This article examines the infrared spectroscopy of polyurethanes, comparing their spectral behavior to the structurally related polyamides. Polyurethanes contain secondary urethane linkages that combine ester- and amide-like character around a shared carbonyl group, and the discussion reviews the resulting N–H stretching, carbonyl, and C–O vibrations. A key diagnostic point is that urethane C=O stretches appear at higher wavenumbers than those of amides, helping distinguish the two polymer classes. The article also covers the diisocyanate precursors used in polyurethane synthesis, which display an intense, broad N=C=O asymmetric stretch near 2277 cm⁻¹.

2. The Infrared Spectra of Polymers II: Polyethylene

Author: Brian C. Smith

Polyethylene remains one of the most important commercial polymers and serves as an excellent model system for learning polymer infrared spectroscopy. This article continues the discussion of polyethylene spectral interpretation, showing how synthesis methods affect polymer morphology and spectroscopic behavior. Particular attention is given to crystalline splitting and methylene rocking vibrations, illustrating how subtle spectral changes reveal structural differences in polyethylene materials.

3. The Infrared Spectra of Polymers III: Hydrocarbon Polymers

Author: Brian C. Smith

This is the third installment in Smith's ongoing series on polymer infrared spectroscopy, building on the earlier discussion of polyethylene to examine two additional hydrocarbon polymers: polypropylene and polystyrene. The article provides detailed analysis of how these materials' infrared spectra differ from one another and from polyethylene, demonstrating how characteristic absorption bands distinguish among hydrocarbon polymer types. The discussion serves as both a practical materials-identification resource and an educational review of infrared spectral interpretation technique.

4. Infrared Spectroscopy of Polymers VIII: Polyesters and the Rule of Three

Author: Brian C. Smith

This article introduces the infrared spectroscopy of ester-containing polymers and presents the author's “Rule of Three” approach for interpreting polyester spectra. Important industrial polymers, including polyethylene terephthalate (PET), are examined in detail. The article reviews ester-group spectroscopy and demonstrates how characteristic carbonyl and C–O stretching bands facilitate the identification and analysis of polyester materials.

5. Decimal Versus Binary Representation of Numbers in Computers

Authors: Howard Mark and Jerome Workman, Jr.

This article examines a practical problem that arises when computers, which store numbers internally in binary form, exchange numerical data externally in decimal notation. The authors show that truncating the number of decimal digits used during data transfer—particularly for spectral data exported in the JCAMP-DX format—can introduce precision loss that compromises downstream chemometric calculations such as calibration modeling. Drawing on the structure of IEEE 754 floating-point representation, they recommend exporting at least nine significant decimal digits to preserve the full information content of the original binary values.

6. Not attributable to a single manuscript (154 views): this entry was recorded for the bare journal-level DOI, https://doi.org/10.56530/SPECTROSCOPY, rather than an individual article.

7. A Quick and Accurate High Performance Liquid Chromatography (HPLC) Method to Determine the Amount of Trimethylamine in Fish Oil Softgels and Multivitamin Softgels Containing Fish Oil

Authors: Mina Fakhary, Fang Xia, Mohamed Koroma, and Martin Dennison

The authors describe a derivatization-based reversed-phase HPLC method for quantifying trimethylamine (TMA), a marker of fish oil rancidity, in fish oil and multivitamin softgel supplements. Using 9-fluorenylmethyl chloroformate derivatization, the method achieves a coefficient of determination (R²) of 0.998 across a linear range of 1–17 ppm. Testing of fresh and aged products showed that TMA levels track with the fish oil raw material used rather than with product age or apparent rancidity, and that the presence of choline does not interfere with TMA measurement. The findings suggest that softgel manufacturing processes themselves do not increase TMA levels over time.

8. Infrared Spectroscopy of Polymers, IX: Pendant Ester Polymers and Polycarbonates

Author: Brian C. Smith

This installment of Smith's polymer series examines pendant ester polymers, such as cellulose acetate, and polycarbonates. The article explains that acetate esters produce a distinctive, high-wavenumber C–C–O stretching peak near 1240 cm⁻¹, then turns to organic carbonates and shows how polycarbonates such as Lexan display three characteristic peaks arising from carbonyl, O–C–O, and O–C–C stretching vibrations. The discussion concludes by demonstrating how infrared spectroscopy can distinguish between different carbonate types and differentiate carbonates from esters based on peak position.

9. Artificial Intelligence in Analytical Spectroscopy, Part II: Examples in Spectroscopy

Authors: Jerome Workman, Jr. and Howard Mark

Continuing a two-part series on artificial intelligence (AI) and machine learning (ML) in analytical chemistry, this article focuses on applications of AI to electronic and vibrational spectroscopy, including deep learning approaches. The authors survey selected literature illustrating how AI and ML have been applied to Raman, infrared (FT-IR), near-infrared (NIR), and UV-vis spectroscopic techniques, offering a sampling of the growing body of research at the intersection of AI and molecular spectroscopy.

10. The Multi-Attribute Method (MAM) for the Characterization of Biopharmaceuticals

Authors: Jared Auclair and Anurag S. Rathore

This article reviews the multi-attribute method (MAM), an LC–MS-based analytical approach that allows multiple critical quality attributes of a biopharmaceutical product—including post-translational modifications and impurities—to be monitored simultaneously in a single analysis. The authors explain how MAM supports Quality by Design frameworks and can offer advantages over traditional orthogonal testing strategies. The discussion also addresses regulatory considerations, implementation in quality control settings, and emerging technologies expected to expand MAM's role across the biopharmaceutical product lifecycle.

References

1. Smith, B. C. Infrared Spectroscopy of Polymers XIII: Polyurethanes. Spectroscopy 2023, 38 (7), 14–16. https://doi.org/10.56530/spectroscopy.fn3378a3.

2. Smith, B. The Infrared Spectra of Polymers II: Polyethylene. Spectroscopy 2021, 36 (9), 24. https://doi.org/10.56530/spectroscopy.xp7081p7.

3. Smith, B. C. The Infrared Spectra of Polymers III: Hydrocarbon Polymers. Spectroscopy 2021, 36 (11). https://doi.org/10.56530/spectroscopy.mh7872q7.

4. Smith, B. C. Infrared Spectroscopy of Polymers VIII: Polyesters and the Rule of Three. Spectroscopy 2022, 37 (10), 25–28. https://doi.org/10.56530/spectroscopy.ta9383e3.

5. Mark, H.; Workman, J., Jr. Decimal Versus Binary Representation of Numbers in Computers. Spectroscopy 2022, 37 (10), 13–20. https://doi.org/10.56530/spectroscopy.mm1179p4.

6. DOI: https://doi.org/10.56530/SPECTROSCOPY for Spectroscopy Magazine (not attributable to a single manuscript).

7. Fakhary, M.; Xia, F.; Koroma, M.; Dennison, M. A Quick and Accurate High Performance Liquid Chromatography (HPLC) Method to Determine the Amount of Trimethylamine in Fish Oil Softgels and Multivitamin Softgels Containing Fish Oil. LCGC North America 2022, 40 (2), 72–76. https://doi.org/10.56530/lcgc.na.bs9787e7.

8. Smith, B. C. Infrared Spectroscopy of Polymers, IX: Pendant Ester Polymers and Polycarbonates. Spectroscopy 2022, 37 (11), 16–19, 31. https://doi.org/10.56530/spectroscopy.xn9369p8.

9. Workman, J., Jr.; Mark, H. Artificial Intelligence in Analytical Spectroscopy, Part II: Examples in Spectroscopy. Spectroscopy 2023, 38 (6), 10–15. https://doi.org/10.56530/spectroscopy.js8781e3.

10. Auclair, J.; Rathore, A. S. The Multi-Attribute Method (MAM) for the Characterization of Biopharmaceuticals. LCGC North America 2021, 39 (1). https://doi.org/10.56530/lcgc.na.gi5577l2.