Full collision energy ramp‐MS² spectral features of natural esters: Salvianolic acid A as a case

Structural identification ofin vitrometabolites for 23-nordeoxycholic acid by structural analogue matching

“…For instance, the so-called featured ions, such as a + , b + , c + , x + , y + , and z + , usually serve as the primary fragment ion species for peptides, 27,28 and similarly, the diagnostic ions, including a − , b − , c − , y − , and z − , frequently dominate the negative MS 2 spectrum of a given ester. 29,30 Hence, similar fragment ion species primarily resulting from the neutral cleavages of H 2 O, CO, HCOOH, and CO 2 are usually observed in the MS 2 spectra of BAs, 31 indicating that it is inherently challenging to achieve isomeric identification of BAs using m / z value profiles. However, the RII features of certain fragment ions have been well demonstrated to show the potential for isomeric differentiation.…”

Full collision energy ramp–pseudo‐multistage mass spectrometry facilitates aglycone identification for glycosides

“…A versatile concept, namely full collision energy ramp (FCER)-MS n , can universally describe the dissociation kinetics. 5,6 More fortunately, when the ions share identical structural geometry, regardless of being quasi-molecular ions or fragment ions, they usually produce the coincident next-generation MS n spectra although the fragment ions might be generated from different dissociation sites, 7 resulting in a viable approach to identify substructure through matching the FCER-MS n spectrum with known molecules. Hence, after that a flavonoid glycoside, for instance, undergoes in-source CID to yield the protonated aglycone (Y 0 + ), the follow-up FCER-pseudo-MS 3 spectrum might be totally consistent with the FCER-MS 2 spectrum of the aglycone.…”

“…A similar program to FCER-MS 2 measurement was applied to Y 0 + (m/z 303.0493) generated from in-source CID of each glycoside (Figure 2A) to construct FCER-pseudo-MS 3 spectrum, while FCER-MS 2 spectrum was built for deprotonated quercetin in parallel. [5][6][7] Each entire spectrum was configured by assembling the sigmoid-or Gaussianshaped breakdown graphs for m/z 303.0493, 165.0186, 153.0182 and 137.0235 that were the primary featured signals in either the pseudo-MS 3 spectrum of each glycoside or the MS 2 spectrum of quercetin.…”