A sensitive radiochromatographic method for the quantitative
determination of compounds labelled with short-lived beta-emitting
radionuclides in microdialysates is described. The method is well suited
for microdialysis (MD) samples, which have small volumes and low
concentrations of compounds. An 18F-labelled (beta+; T(1/2)=109.8 min)
radiopharmaceutical, (1R,2S)-4-[18F]fluorometaraminol (FMR), was
injected intravenously into rats, and microdialysis fractions were then
collected from the blood at 15 min intervals. Fractions were analyzed
for FMR and its radioactive metabolites by planar chromatography
combined with digital photostimulated luminescence autoradiography. The
lowest detectable 18F-radioactivity was 0.24 Bq/application and the
limit of quantification was 0.31 Bq/application with 4-16 h exposure.
The method was found to be highly sensitive and linear in the range of
0.1 Bq-2 kBq. This method thus allows the quantification of
beta-emitting radiopharmaceuticals in sequential microdialysis fractions
with good time-resolution.