Comparison of two full automatic synthesis methods of 9-(4-[18F]fluoro-3-hydroxymethylbutyl)guanine using different chemistry modules

We have developed synthesis methods for 9-(4-[18F]fluoro-3-hydroxymethylbutyl)guanine ([18F]FHBG) using two commercial automatic chemistry modules, Tracerlab MX and Explora RN, and compared radiochemical yields. Synthesis conditions and sequence programs were modified for two modules because both these modules have different mechanical structures, including heater type, vacuum system, reactor, and tubing size. Synthesis using the Tracerlab MX module showed a 21.0±3.8% yield of radiochemical, which was 98±0.9% pure; the total preparation time was 63.0±5.0 min including an HPLC purification step. In contrast, synthesis using the Explora RN module showed a 32.0±1.2% yield of radiochemical, which was 99.0±0.6% pure; the total preparation time was 38±2 min, using different HPLC purification conditions and without the HPLC solvent evaporation step.