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. Author manuscript; available in PMC: 2014 Oct 15.
Published in final edited form as: Anal Chem. 2013 Sep 24;85(20):10.1021/ac402104u. doi: 10.1021/ac402104u

Figure 5. Analysis of FA double bond positional isomers present in human serum.

Figure 5

AMPP-derivatized non-esterified FAs and esterified FAs in triglycerides (TG-FA) in pooled normal human serum samples were prepared as described in Materials and Methods. The top panels are PIS of m/z 183 spectra for non-esterified FAs (A) and TG-FAs (B), where I.S. stands for the internal standards of non-esterified FA (i.e., d4-16:0 FA) in (A) or esterified FA released from the TG internal standard (i.e., 17:1 TG) in (B). The red insets are vertically enlarged spectra. Panels (a)–(c) are tandem mass spectra of 18:1, 18:2 and 18:3 FAs in human serum. “*” and “#”are as indicated in Fig. 2. Panel (d) represents the tandem mass spectra of the 18:3 FA isomeric mixtures prepared from the authentic isomers at the calculated compositions from (c). Panel (e) represents the simulated in silico spectra of the same 18:3 FA isomeric mixtures.