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Eur. J. Mass Spectrom. DOI: 10.1255/ejms.529 |
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API-ESI mass spectra of glucose and 2-fluorodeoxyglucose for quantitative analysis of FDG by HPLC | ||
F. Macásek,* P. Brúder and A. Patakyová |
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ABSTRACT: | ||
The 2-deoxy-2-fluoro-D-glucose (FDG) labelled by fluorine-18 is the most widely used radiopharmaceutical for positron emission tomography (PET). For HPLC/MS assay and quality control, the mass spectra of FDG and glucose (Glc) in organic/water solutions were studied by the direct injection (FIA) and in chromatographic eluate. In acetonitrile (MeCN).025% ammonium formate (NH4HCO2) solvent (80:20), glucose electrospray ionisation (ESI) provides as the most intensive the positive ions M.NH4+ and 2M.Na+ (M=Glc or FDG). Formation of the latter and also of M.MeCN.Na+ and 2MeCN.Na+ is typical for presence of NaCl in ESI inlet. The positive ions include heavier ions corresponding to the impurities obtained by HPLC, but also to the cross-ring fragmentation of complexes (2FDG.aMeCN-X)L, where a=0 or 1, L is either Na+ or NH4+, and X is a fragmented pyranose or anhydropyranose residue. The second most abundant Glc negative ion is m/z=359 which was interpreted as (2Glc-H+)-. The negative ion spectrum of FDG has dominating lines of FDG.HCO2 ions at m/z 227, and also at 363, (2FDG-H+). The last one is suppressed in presence of NaCl at the molar ratio 4:1 to NH4HCO2, and the ions m/z 217 and 219, i.e. FDG.Cl- become three times more intensive than FDG.HCO2. The latter appears most suitable for an analytical signal for chemical analysis of FDG at m/z 226 and 227. The limits of FDG quantitation (LOQ) 19 ng and 21 ng were found for the 200+ and 227 ion signal respectively, and are wholly adequate for attestation of total FDG contents in radiopharmaceuticals. | ||
Keywords: ESI, HPLC, LC/MS analysis, saccharides, glucose, fluorodeoxyglucose, FDG, radiopharmaceuticals |
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