Determination of Double Bond Location in Fatty Acids by Manganese Adduction and Electron Induced Dissociation

摘要

Double bond locations in fatty acids can be determinednfrom characteristic charge-remote fragmentation patternsnof alkali metal-adducted fatty acids following high energyncollision activated dissociation (CAD). With low energynCAD, several chemical derivatization methods, includingnozonization, epoxidation, and hydroxylation, have beennused to generate characteristic fragments. However, highnenergy CAD is not universally available and involves a highndegree of scattering, causing product ion loss. Further,nderivatization reactions involve side reactions and samplenloss. Here, we analyzed metal-adducted fatty acids toninvestigate the utility of electron induced dissociationn(EID) for determining double bond location. EID has beennproposed to involve both electronic excitation, similar tonhigh energy CAD, and vibrational exciation. Variousnmetals (Li, Zn, Co, Ni, Mg, Ca, Fe, and Mn) wereninvestigated to fix one charge at the carboxylate end ofnfatty acids to promote charge-remote fragmentation. EIDnof Mn(II)-adducted fatty acids allowed determination ofnall double bond locations of arachidonic acid, linolenicnacid, oleic acid, and stearic acid. For Mn(II)-adductednfatty acids, reduced characteristic charge-remote productnion abundances at the double bond positions are indicativenof double bond locations. However, other metalnadducts did not generally provide characteristic productnion abundances at all double bond locations.