Characterization of FDG-6-P daughter ion.
Panel A illustrates the working hypothesis, while panels B, C and D represent experimental data. A, Predicted FDG-6-P fragmentation pattern. Assuming that FDG metabolism is similar to glucose, it was predicted that FDG-6-P would be generated in vivo. In turn, FDG-6-P is likely to generate two products with molecular mass of 139 and 122 respectively, in the process of mass spectrometry. Experimental identification of these products would be indicative of in vivo FDG phosphorylation. B, Retention time after injection of FDG-6-P standard to the LC/MS/MS C, Identification of a peak associated with daughter ion of 139.2 mass-to-charge (m/z) units after injection of FDG-6-P standard to the LC/MS/MS D, A standard curve demonstrating proportionality between amount of daughter ion species, 139.2 m/z, and its parent molecule, FDG-6-P.