PIJEIRA, MARTHA S.O.SANTOS, SOFIA N. dosARAUJO, YASNIEL B.LAPOLLI, ANDRE L.WANDERMUREN, MARCIO N.RIERA, ZALUA R.CARVALHO, IVONEELSINGA, PHILIP H.BERNARDES, EMERSON S.2022-12-062022-12-062022PIJEIRA, MARTHA S.O.; SANTOS, SOFIA N. dos; ARAUJO, YASNIEL B.; LAPOLLI, ANDRE L.; WANDERMUREN, MARCIO N.; RIERA, ZALUA R.; CARVALHO, IVONE; ELSINGA, PHILIP H.; BERNARDES, EMERSON S. A closer look at the synthesis of 2‑[18F] fluoroethyl tosylate to minimize the formation of volatile side‑products. <b>EJNMMI Radiopharmacy and Chemistry</b>, v. 7, n. 1, p. 1-15, 2022. DOI: <a href="https://dx.doi.org/10.1186/s41181-022-00179-8">10.1186/s41181-022-00179-8</a>. Disponível em: http://repositorio.ipen.br/handle/123456789/33410.2365-421Xhttp://repositorio.ipen.br/handle/123456789/33410Background: 2-[18F]Fluoroethyltosylate ([18F]FEtOTs) is a well-known 18F-fluoroalkylating agent widely used to synthesize radiotracers for positron emission tomography. The widespread use of [18F]FEtOTs is due in part to its low volatility when compared to other halide and sulfonate building blocks. In this work, the radioactive volatile side-products formed during the synthesis of [18F]FEtOTs were identified and characterized for the first time, and an optimization of the reaction conditions to minimize their formation was proposed. Results: In order to characterize the volatiles produced during [18F]FEtOTs synthesis, the reaction mixtures of both cold FEtOTs and [18F]FEtOTs were co-injected onto the HPLC system. The radioactive peaks corresponding to the volatile compounds were collected, analyzed through headspace gas chromatography mass spectrometry sampler (HS-GC–MS) and identified as vinyl fluoride ([19F]VF) and 2-fluoroethanol ([19F]FEOH). By using a rotatable central composite design with a two-level full factorial core of two factors (22), it was determined that temperature and time are independent variables which affect the generation of [18F]VF and [18F]FEOH during the radiosynthesis of [18F]FEtOTs. In addition, in order to reduce the formation of the volatiles ([18F]VF and [18F]FEOH) and increase the yield of [18F]FEtOTs, it was demonstrated that the molar ratio of base to precursor must also be considered. Conclusion: [18F]VF and [18F]FEOH are volatile side-products formed during the radiosynthesis of [18F]FEtOTs, whose yields depend on the reaction time, temperature, and the molar ratio of base to precursor. Therefore, special care should be taken during the radiosynthesis and subsequent reactions using [18F]FEOTs in order to avoid environmental contamination and to improve the yield of the desired products.1-15openAccessfluoridesfluorine 18gasesradioactive materialsradiation protectionpositron computed tomographyArtigo de periódico1710.1186/s41181-022-00179-80000-0002-0029-7313https://orcid.org/0000-0002-0029-7313Sem Percentil84.25