IR and Raman dual modality markers differentiate among three bis-phenols: BPA, BPS and BPF

Authors: Chao, Kuanglin - Kevin Chao; SCHMIDT, WALTER - Collaborator; Qin, Jianwei - Tony Qin; Kim, Moon; TAO, FEIFEI - University Of Florida

Submitted to: Applied Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2024
Publication Date: 7/10/2024
Citation: Chao, K., Schmidt, W.F., Qin, J., Kim, M.S., Tao, F. 2024. IR and Raman dual modality markers differentiate among three bis-phenols: BPA, BPS and BPF. Applied Sciences. 14(14): Article e6064. https://doi.org/10.3390/app14146064.
DOI: https://doi.org/10.3390/app14146064

Interpretive Summary: Bisphenol A (BPA) has been used as a plasticizer in polycarbonate plastics for containers that store food and beverages. Regulatory measures have restricted the use of BPA in plastic formulations especially for those which come in contact with food products. Rapid, accurate spectroscopic measurements are required for uniquely distinguishing BPA from other bis-phenols. ARS scientists in Beltsville developed a rapid, accurate, and sensitive dual-modality IR and Raman spectroscopic technique to distinguish BPA from other commercially used bis-phenols (BPS and BPF). Dual modality analysis enables addressing exactly the wavenumbers in which IR and Raman spectra are the most different. Our analysis finds the major phenolic ring vibrational mode intensities in BPA, BPS and BPF are significantly different, sufficient to identify one from the other despite their structural similarity. This paper provides practical information for the use of dual-modality technology for food detection, which will benefit researchers who have interest in developing and using the dual-modality techniques for safety and quality inspection of food products.

Technical Abstract: bis-Phenols BPA, BPS, and BPF are important polymer industry plasticizers. Regulatory measures have restricted the use of BPA in plastic formulations especially for those which come in contact with food products. Rapid, accurate spectroscopic measurements are required for distinguishing which of the three are present. The bis-phenol groups are structurally identical. The second set of bis-groups (CH3-C-CH3, O=S=O and H-C-H respectively) have discretely different chemically but vibrational modes corresponding to these groups are not unique identifiers, routinely overlap-ping with wavenumbers present in others of the three. Dual modality method identifies the specific wavenumbers in which IR signal is near zero and Raman relative intensity is maximum and those in which Raman signal is minimum and IR signal is maximum. The normalized intensity ratio between IR/Raman enhances signal [BPA 10.6 (1508 cm-1); BPS 7.4 (751 cm-1); BPF 5.1 (1100 cm-1). The ratio between Raman/IR in BPF is also enhanced 6.3 (845 cm-1). Discerning which specific wavenumbers are most enhanced is experimentally accessible, though not necessarily at present theoretically predictable. This study demonstrates that IR and Raman spectra are not just complimentary, but together are confirmatory even when the normalized intensity ratio of corresponding wavenumbers are the most different.