Investigation on fragmentation pathways of bisphenols by using electrospray ionization Orbitrap mass spectrometry

Rationale: Bisphenols, such as bisphenol A (BPA) and bisphenol S (BPS), are widely used in industrial products, although they have been demonstrated to be environmental contaminants with toxicity. However, few studies on the mass spectrometric fragmentation pathway of these compounds have been reported using high-resolution mass spectrometry (HRMS). Methods: The MS/MS fragmentations of nine bisphenols, together with several corresponding isotope-labeled compounds, were studied by Orbitrap MS using electrospray ionization (ESI) in negative ion mode and higher energy collisional-dissociation (HCD). The [M − H]⁻ ions of the compounds formed by ESI were selected as the precursor ions for MS/MS. The accurate m/z values for product ions were acquired to deduce the elemental compositions and fragmentation pathways. Results: The elemental compositions of the ions were calculated from the accurate mass data. Common MS/MS product ions and characteristic neutral losses were summarized. Six bisphenols formed the common product ion at m/z 93 (C₆H₅O). The [M − H]⁻ ions of five bisphenols were found to lose a phenol group (C₆H₅OH). Four bisphenols formed the [M − H − CH₄]⁻ ion. The proposed fragmentation pathways of representative compounds of BPA and BPS were verified from the analysis of isotope-labeled compounds. Conclusions: The MS/MS fragmentation pathways of nine bisphenols were, for the first time, systematically investigated with HRMS. The obtained data could be valuable for the identification of a variety of bisphenols in environmental and biological samples.