Fig. 2.

Tandem mass spectra of C16:0-CoA using positive (A) and negative (B) ionization modes. Both ionization mode spectra were collected using the same sample and ion source conditions, the DP to yield the best peak height for the singly (de)protonated molecular ion, and the collision energy (CE), collisionally activated dissociation (CAD) gas setting, and collision cell exit potential (CXP) to yield the best peak height for the most abundant product ion retaining the acyl chain moiety (499.4 m/z in positive mode and 657.4 m/z in negative mode). Uppercase letter labels by the peaks denote the systematic nomenclature proposed in Fig. 3. The C16:0-CoA structures shown with each ionization mode propose fragmentations consistent with the tandem mass spectra. The horizontal arrow from the precursor ion to the product ion indicates a neutral loss of 507.0 Da. Spectra (summation of 1 min scans) were collected during the infusion (5 μl/min) of C16:0-CoA at a concentration of 1 pmol/μl.