Optimization and validation of [13N]-NH3 production for clinical studies of positron emission tomography in the evaluation of myocardial perfusion

The present work aims to validate the [¹³N]-NH₃ production for human studies of myocardial perfusion using a cyclotron from a Portuguese public institution and an automatic synthesis module. According to specifications of European Pharmacopeia (Ph. Eur.) 8.2., 3 consecutives batches were evaluated for this purpose. Results showed a clear and colorless product and pH values between 4,5 e 8,5. The chemical purity was confirmed by the colorimetric test and the samples were identified as [¹³N]-NH₃, by ionic chromatography, gamma ray spectroscopy and half-life determination. Radiochemical and radionuclidic purity were confirmed, corresponding a minimum of 99% of total radioactivity to [¹³N] and a percentage of impurities less than 1%, 2 hours after the end of synthesis. Tests for sterility and for presence of bacterial endotoxins were also performed.