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This function, related to the absorption index via the Kramers\u00ad\u2013Kronig relations, is derived from corrections applied to absorbance spectra to ensure compliance with wave optics principles. In this note, we demonstrate that, at least in the quasi-thermodynamically ideal binary system of benzene and toluene, classical quantitative chemometrics performs better when based on refractive index spectra than when based on absorption index spectra. The primary reason for this difference is that the refractive index at a given wavenumber integrates all changes resulting from absorptions at higher wavenumbers. This property is particularly advantageous in non-absorbing regions, where absorption index spectra provide no information about the system's composition.<\/jats:p>","DOI":"10.1177\/00037028251345774","type":"journal-article","created":{"date-parts":[[2025,6,26]],"date-time":"2025-06-26T03:00:27Z","timestamp":1750906827000},"page":"1659-1664","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":6,"title":["Quantitative Chemometrics Using Refractive Index Spectra"],"prefix":"10.1177","volume":"79","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9396-7365","authenticated-orcid":false,"given":"Thomas G.","family":"Mayerh\u00f6fer","sequence":"first","affiliation":[{"name":"Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Str. 9, 07745 Jena, Germany"},{"name":"Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University, Helmholtzweg 4, 07743 Jena, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Oleksii","family":"Ilchenko","sequence":"additional","affiliation":[{"name":"The Danish National Research Foundation and Villum Foundation's Center for Intelligent Drug Delivery and Sensing Using Microcontainers and Nanomechanics (IDUN), Department of Health Technology, Technical University of Denmark, \u00d8rsteds Plads Building 345C, Kgs. 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