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.
CONCLUSIONS: [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.
结果:为了表征[18F]FEtOTs合成过程中产生的挥发物,将冷FEtOTs和[18F]FEtOTs的反应混合物共同注射到HPLC系统上。收集对应于挥发性化合物的放射性峰,通过顶空气相色谱-质谱采样器(HS-GC-MS)进行分析,并鉴定为氟乙烯([19F]VF)和2-氟乙醇([19F]FEOH)。通过使用具有两个因素的两级全阶乘核心的可旋转中心复合设计(22),确定温度和时间是在[18F]FEtOTs的放射合成期间影响[18F]VF和[18F]FEOH的产生的独立变量。此外,为了减少挥发物([18F]VF和[18F]FEOH)的形成并增加[18F]FEtOTs的产量,已经证明,还必须考虑碱与前体的摩尔比。
结论:[18F]VF和[18F]FEOH是[18F]FEtOTs放射合成过程中形成的挥发性副产物,其收率取决于反应时间,温度,和碱与前体的摩尔比。因此,在使用[18F]FEOTs的放射合成和随后的反应期间应特别小心,以避免环境污染并提高所需产物的产率。