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Table 1 Calculation of specific radioactivity from the peak areas of [ 11 C] species and [M + 1] carrier in radiotracers

From: Characterization of fast-decaying PET radiotracers solely through LC-MS/MS of constituent radioactive and carrier isotopologues

Radiotracer Elution time a Peak areas SA e(GBq/μmol) SA f(GBq/μmol)
11C 11C M + 1 12C Ratio
(h:min:s) ×10 −4 ×10 −3b ×10 −6 ×10 −7c ×10 4d
[11C]PBR28 10:21:23 2.3920 1.8531 2.6506 2.9849 7.9240 270.4 330.3
10:42:55 1.2103 0.9376 2.7072 3.0486 3.9271 134.0 340.6
[11C](R)-Rolipram 11:15:49 0.5745 0.7009 1.5974 1.1970 4.7490 162.1 463.3
11:37:19 0.2827 0.3449 1.6280 1.2199 2.2936 78.3 464.9
  1. aElution time for coeluting LC peaks of [11C]species and [M + 1]carrier; bcalculated peak area for [11C, M + 1]species (Equation 1); ccalculated peak area from measured M + 1/12C ratio in PBR28 and (R)-rolipram; dpeak area ratio of [11C]species to the sum of carrier and [11C]species; especific radioactivity calculated from the peak area ratio; fdecay-corrected specific radioactivity.