Loop와 HPLC Purification 방법보다 더 높은 비방사능을 보여주는 카트리지 Methylation과 Purification을 이용한 손쉬운 [¹¹C]PIB 합성

Facile [¹¹C]PIB Synthesis Using an On-cartridge Methylation and Purification Showed Higher Specific Activity than Conventional Method Using Loop and High Performance Liquid Chromatography Purification

[¹¹C]PIB synthesis has been performed by a loop-methylation and HPLC purification in our lab. However, this method is time-consuming and requires complicated systems. Thus, we developed an on-cartridge method which simplified the synthetic procedure and reduced time greatly by removing HPLC purification step. We compared 6 different cartridges and evaluated the [¹¹C]PIB production yields and specific activities. [¹¹C]MeOTf was synthesized by using TRACERlab FXC Pro and was transferred into the cartridge by blowing with helium gas for 3 min. To remove byproducts and impurities, cartridges were washed out by 20 mL of 30% EtOH in 0.5 M NaH2PO4 solution (pH 5.1) and 10 mL of distilled water. And then, [¹¹C]PIB was eluted by 5 mL of 30% EtOH in 0.5 M NaH2PO4 into the collecting vial containing 10 mL saline. Among the 6 cartridges, only tC18 environmental cartridge could remove impurities and byproducts from [¹¹C]PIB completely and showed higher specific activity than traditional HPLC purification method. This method took only 8 ~ 9 min from methylation to formulation. For the tC18 environmental cartridge and conventional HPLC loop methods, the radiochemical yields were 12.3±2.2% and 13.9±4.4%, respectively, and the molar activities were 420.6±20.4 GBq/μmol (n=3) and 78.7±39.7 GBq/μmol (n=41), respectively. We successfully developed a facile on-cartridge methylation method for [¹¹C]PIB synthesis which enabled the procedure more simple and rapid, and showed higher molar radio-activity than HPLC purification method.