LTQ FT MS Accurate Mass and SRM Data Dependent Exclusion MSⁿ Measurements for Structure Determination of FK228 and Its Metabolites

抄録

MS² fragments are produced by cleavage of all protonated molecules at the lone electron pairs of heteroatoms or the π electrons of double bonds of FK228. Usually, data dependent MS³ measurement cleaves only MS² fragment of highest intensity that normally does not contain important metabolic sites. New SRM (selected reaction monitoring) data dependent exclusion MSⁿ measurement makes it possible to obtain MS³ fragmentation data for all MS² fragments, useful for structural determination of FK228 and its metabolites using ESI ion trap. The two different fragmentation pathways of FK228, of which fragment ions had the different elemental composition, were estimated. The accurate masses of FK228 fragment ions Fa1 (or Fb1) and Fa2 (or Fb2) were measured by LTQ FT MS to compare with those calculated exact masses. The fragmentation pathway of formers was correct as the result. LTQ FT MS accurate mass and SRM data dependent exclusion MSⁿ measurements are required for the structure determination of FK228 and its metabolites.