Mass spectrometry (MS) has longstanding applications in radiochemistry laboratories, stemming from carbon-dating. However, research on the development of radiotracers for molecular imaging with either positron emission tomography (PET) or single photon emission computed tomography has yet to take full advantage of MS. This inertia has been attributed to the relatively low concentrations of radiopharmaceutical formulations and lack of access to the required MS equipment due to the high costs for purchase and maintenance of specialized MS systems. To date, single quadrupole (SQ)-MS coupled to liquid chromatography (LC) systems is the main form of MS that has been used in radiochemistry laboratories. These LC–MS systems are primarily used for assessing the chemical purity of radiolabeling precursor or standard molecules but also have applications in the determination of metabolites. Herein, we highlight personal experiences using a compact SQ-MS in our PET radiochemistry laboratories, to monitor the small amounts of carrier observed in most radiotracer preparations, even at high molar activities. The use of a SQ-MS in the observation of the low mass associated with non-radioactive species which are formed along with the radiotracer from the trace amounts of carrier found is demonstrated. Herein, we describe a pre-concentration system to detect dilute radiopharmaceutical formulations and metabolite analyses by SQ-MS. Selected examples where SQ-MS was critical for optimization of radiochemical reactions and for unequivocal characterization of radiotracers are showcased. We also illustrate examples where SQ-MS can be applied in identification of radiometal complexes and development of a new purification methodology for Pd-catalyzed radiofluorination reactions, shedding light on the identity of metal complexes present in the labelling solution.

质谱（MS）源于碳约会，在放射化学实验室中有着长期的应用。但是，对于用正电子发射断层扫描（PET）或单光子发射计算机断层扫描进行分子成像的放射性示踪剂的研究尚未充分利用MS的优势。该惯性归因于放射性药物制剂的相对较低的浓度以及由于购买和维护专用MS系统的高成本而无法获得所需的MS设备。迄今为止，单四极杆（SQ）-MS与液相色谱（LC）系统耦合是MS已用于放射化学实验室的主要形式。这些LC-MS系统主要用于评估放射性标记前体或标准分子的化学纯度，但也可用于测定代谢物。在此，我们重点介绍了在我们的PET放射化学实验室中使用紧凑型SQ-MS来监视大多数放射性示踪剂制剂中观察到的少量载体（即使在高摩尔活动下）的个人经验。证明了SQ-MS在观察与非放射性物质相关的低质量中的应用，这些非放射性物质是与放射性示踪剂一起形成的，这些放射性示踪剂是由发现的痕量载体形成的。在本文中，我们描述了一种预浓缩系统，用于通过SQ-MS检测稀释的放射性药物制剂和代谢物分析。展示了SQ-MS对于优化放射化学反应和明确确定放射性示踪剂至关重要的一些实例。我们还举例说明了可以将SQ-MS用于放射性金属配合物鉴定和开发新的Pd催化的放射性氟化反应纯化方法的实例，从而阐明了标记溶液中存在的金属配合物的身份。