Neutral losses of sodium benzoate and benzoic acid in the fragmentation of the [M + Na](+) ions of methoxyfenozide and tebufenozide via intramolecular rearrangement in electrospray ionization tandem mass spectrometry.

Title Neutral losses of sodium benzoate and benzoic acid in the fragmentation of the [M + Na](+) ions of methoxyfenozide and tebufenozide via intramolecular rearrangement in electrospray ionization tandem mass spectrometry.
Authors Y. Chai; G. Gao; S. Shen; X. Liu; C. Lu
Journal Rapid Commun Mass Spectrom
DOI 10.1002/rcm.7785
Abstract

RATIONALE: Electrospray ionization (ESI) tandem mass spectrometry can be applied to determine structural information about organic compounds. The [M + Na](+) ion is one of the major precursor ions in ESI mass spectrometry, but its fragmentation mechanism study is still insufficient. This study reveals the interesting fragmentation reactions of the [M + Na](+) ions of methoxyfenozide and tebufenozide.

METHODS: The fragmentations of the [M + Na](+) , [M + Li](+) , and [M + H](+) ions of methoxyfenozide and tebufenozide were studied using a hybrid quadrupole-orbitrap mass spectrometer and an ion trap mass spectrometer. A hydrogen/deuterium (H/D)-exchange experiment in the amide group of methoxyfenozide allowed for the confirmation of the fragmentation mechanism. Density functional theory (DFT) calculations were performed for a further understanding of the fragmentation mechanism of the [M + Na](+) ion of methoxyfenozide.

RESULTS: Neutral losses of sodium benzoate and benzoic acid in the fragmentation of the [M + Na](+) ions of methoxyfenozide and tebufenozide were observed as the major fragmentation pathways. In contrast, similar fragmentations were not observed or minor pathways in the fragmentation of the [M + Li](+) and [M + H](+) ions of methoxyfenozide and tebufenozide. In addition, a minor product ion resulting from loss of NaOH was identified, which was the first reported example in the fragmentation of sodiated compounds in mass spectrometry.

CONCLUSIONS: Losses of sodium benzoate and benzoic acid in the fragmentation of the [M + Na](+) ions of methoxyfenozide and tebufenozide are proposed to be formed through an intramolecular rearrangement reaction, which is supported by DFT calculations. An H/D-exchange experiment confirms that the carboxyl hydrogen of benzoic acid and the hydrogen of NaOH exclusively derive from the amide hydrogen of the precursor ion. This study enriches our knowledge on the Na(+) -induced fragmentation reactions. Copyright © 2016 John Wiley & Sons, Ltd.

Citation Y. Chai; G. Gao; S. Shen; X. Liu; C. Lu.Neutral losses of sodium benzoate and benzoic acid in the fragmentation of the [M + Na](+) ions of methoxyfenozide and tebufenozide via intramolecular rearrangement in electrospray ionization tandem mass spectrometry.. Rapid Commun Mass Spectrom. 2017;31(3):245252. doi:10.1002/rcm.7785

Related Elements

Sodium

Sodium Bohr ModelSee more Sodium products. Sodium (atomic symbol: Na, atomic number: 11) is a Block D, Group 5, Period 4 element with an atomic weight of 22.989769. The number of electrons in each of Sodium's shells is [2, 8, 1] and its electron configuration is [Ne] 3s1. The sodium atom has a radius of 185.8 pm and a Van der Waals radius of 227 pm. Sodium was discovered and first isolated by Sir Humphrey Davy in 1807. In its elemental form, sodium has a silvery-white metallic appearance. It is the sixth most abundant element, making up 2.6 % of the earth's crust. Sodium does not occur in nature as a free element and must be extracted from its compounds (e.g., feldspars, sodalite, and rock salt). The name Sodium is thought to come from the Arabic word suda, meaning "headache" (due to sodium carbonate's headache-alleviating properties), and its elemental symbol Na comes from natrium, its Latin name.

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