We have demonstrated two separate charge switching approaches for the detailed structural identification of BCFAs. The first approach utilizes an entirely gas-phase strategy in which FA anions are transformed via charge inversion ion/ion reactions with magnesium bis-terpyridine reagent dications, yielding abundant [FA -H + MgTerpy] + complex cations. Upon collisional activation, charge inverted BCFA complex cations fragment provide distinct diagnostic product ions indicative of methyl chain branching site. Importantly, the presented MS n gas-phase charge inversion strategy can readily be extended to identify methyl chain branching site on saturated fatty acyl chains esterified in glycerophospholipid structures. However, for shotgun approaches, the existence of multiple isomeric species within a complex mixture may become problematic and hinder accurate BCFA identification. In addition, the gas-phase ion/ion reactions require specialized instrument modifications and highly trained personnel to conduct these analyses. Thus, to improve isomeric mixture analysis performance and ease of use, an LC-MS/MS method employing post-column charge switching derivatization was established based on conventional LC and MS platforms. In this approach, BCFA isomers are effectively separated from each other and from their straightchain counterparts. Excellent chromatographic resolution alone affords the accurate identification of saturated FA isomers based on retention time matching with authentic reference standards. However, given that several BCFA reference standards are not readily or commercially available, post-column charge switch derivatization facilitated by a continual infusion of magnesium bis-terpyridine reagent solution and subsequent MS/MS affords facile identification of methyl branching site by exploiting the generation of significant indicator product ions influenced by acyl chain branching. Consequently, post-column generation of MgTerpy-adducted FAs permits the localization of methyl chain branching site in the absence of authentic reference standards. The analysis of intact methyl branched complex lipids could not be achieved using this configuration, as it would first require condensed-phase hydrolysis of ester bonds linking acyl chains to the glycerol backbone of complex lipids and subsequent loss of information on the intact structure.