Theoretical and experimental studies on hydrogen migration in dissociative ionization of the methanol monocation to molecular ions H and HO.

The dissociative ionization processes of the methanol monocation CHOH to H + CHO and HO + CH are studied by method, and hydrogen migration processes are confirmed in these two dissociation processes. Due to the positive charge assignment in dissociation processes, the fragmentation pathways of CHOH to H + CHO and CHOH to HO + CH are also calculated. The calculation results show that a neutral H moiety in the methanol monocation CHOH is the origin of the formation of H , and the ejection of fragment ions H and HO is more difficult than CHO and CH respectively.

Sphingolipidomic Profiling of Rat Serum by UPLC-Q-TOF-MS: Application to Rheumatoid Arthritis Study.

Sphingolipids (SPLs) are biologically important molecules, but the structural diversity and complexity of SPLs brings significant analytical challenges for their study. In this paper, we have developed an UPLC-Q-TOF-MS-based sphingolipidomic approach for the comprehensive identification and quantification of SPLs in rat serum. A total of 120 SPLs covering seven subcategories were identified for the first time.