Consecutive Fragmentation Mechanisms of Protonated Ferulic Acid Probed by Infrared Multiple Photon Dissociation Spectroscopy and Electronic Structure Calculations

• Published in: Journal of the American Society for Mass Spectrometry Vol. 23; no. 10; pp. 1697 - 1706
• Main Authors: Martens, Sabrina M., Marta, Rick A., Martens, Jonathan K., McMahon, Terry B.
• Format: Journal Article
• Language: English
• Published: New York Springer-Verlag 01.10.2012; Elsevier; Springer Nature B.V
• Subjects: Acids; Analytical Chemistry; Bioinformatics; Biotechnology; Carbon monoxide; Carbon Monoxide - chemistry; Chemistry; Chemistry and Materials Science; Coumaric Acids - chemistry; Diagnostic systems; Electronic structure; Exact sciences and technology; Ferulic acid; Fragmentation; Gases - chemistry; Infrared spectroscopy; Ions - chemistry; Isomerism; Mass spectrometry; Mass Spectrometry - methods; Mathematical analysis; Methanol - chemistry; Organic Chemistry; Proteomics; Reactivity and mechanisms; Research Article; Spectrum analysis; Thermodynamics; Energetics; IRMPD; Free electron laser; Ion structure; Density functional theory; Vibrational spectra; Ferulic acid; Gas phase fragmentation; Phenolic acid; Theoretical study; Fragmentation pattern; Photodissociation; Multiphoton process; Vibrational transition; Protonated form; Density functional method; Infrared radiation; Gas phase; Mass spectrometry
• ISSN: 1044-0305; 1879-1123
• DOI: 10.1007/s13361-012-0438-3

Protonated ferulic acid and its principle fragment ion have been characterized using infrared multiple photon dissociation spectroscopy and electronic structure calculations at the B3LYP/6-311 + G(d,p) level of theory. Due to its extensively conjugated structure, protonated ferulic acid is observed to yield three stable fragment ions in IRMPD experiments. It is proposed that two parallel fragmentation pathways of protonated ferulic acid are being observed. The first pathway involves proton transfer, resulting in the loss of water and subsequently carbon monoxide, producing fragment ions m/z 177 and 149, respectively. Optimization of m/z 177 yields a species containing an acylium group, which is supported by a diagnostic peak in the IRMPD spectrum at 2168 cm −1 . The second pathway involves an alternate proton transfer leading to loss of methanol and rearrangement to a five-membered ring.