Formation of [M + 15]+ ions from aromatic aldehydes by use of methanol: in-source aldolization reaction in electrospray ionization mass spectrometry

✍ Scribed by Lin Wang; Yunfeng Chai; Peijun Tu; Cuirong Sun; Yuanjiang Pan

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 235 KB
• Volume: 46
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.1994

✦ Synopsis

Unexpected [M + 15] + ions were formed during the analysis of aromatic aldehydes by use of methanol in positive-ion electrospray ionization mass spectrometry. Aromatic aldehydes with electron-withdrawing groups or electron-donating groups were all tested to make sure the universality. All the aromatic aldehydes studied with methanol as the solvent could generate [M + 15] + ion, and for most of them, the [M + 15] + ion was more intense than the [M + H] + ion. Deuterium-labeling experiment, high-performance liquid chromatography-MS experiment, collision-induced dissociation experiment, and theoretical calculations were performed to identify the formation of [M + 15] + ion. The proposed reaction mechanism is a gas-phase aldol reaction between protonated aromatic aldehydes and methanol occurring in electrospray source. Understanding and using this unique gas-phase ion/molecule reaction can indeed offer a novel and fast approach for the direct identification of aromatic aldehydes.