We are currently working on the structural elucidation of plant fractions and came across data via LC-MS/MS analyses for the structural elucidation of plant extracts. In the negative mode, I identified an unusual adduct [M-H+114]- for certain deprotonated ions [M-H]-, despite the absence of TFA in the mobile phase. I acquired two pieces with m/z values of 117 and 67. Does anyone know the origin of this adduct and its fragments?

I found different fragment values after inputting the m/z values into the mass spectrum databases MassBank and analyzing the fragmentation patterns for structural insights.

Thanks