A convenient and efficient solid phase extraction-based pathway for purification of melanin-targeted probe 18F-P3BZA

Abstract N-(2-(diethylamino)-ethyl)-18F-5-fluoropicolinamid (18F-P3BZA) is a promising alternative probe for early diagnosis of malignant melanoma. Developing an efficient and timesaving method for 18F-P3BZA purification is necessary because this procedure is able to remove the unreacted precursor and undesired radioactive substances in a short time so that reducing their impacts on imaging and also decreasing the 18F-P3BZA loss caused by 18F decay. Herein, we investigated a solid phase extraction-based method for 18F-P3BZA purification by use of a single C18 light cartridge and found that eluting crude product-captured C18 light cartridge with 20 mL 0.01 M NH4HCO3 and then 2 mL ethanol/0.01 M NH4HCO3 (1/4, v/v) was capable of giving 18F-P3BZA with a high radiochemical purity and an extremely low precursor content. Furthermore, this purification method allowed automated radiosynthesis of 18F-P3BZA to be completed within 40 min, which was much faster than that of previous studies. In addition, this purification pathway was low cost and easily to be achieved, thus possessing potential to facilitate the universalness of 18F-P3BZA.