Determination of the radiochemical purity of 99mTc-Tetrofosmin: comparision between five methods

摘要

GOAL:The manufacturing and distribution of strips of instant thin-layer chromatography withsilica gel (ITLC-SG) (reference method) is currently discontinued so there is a need for analternative method for the determination of radiochemical purity (RCP) of99mTc-tetrofosmin.This study aims to compare five alternative methods proposed by the producer to determinethe RCP of99mTc-tetrofosmin.METHODS:Nineteen vials of tetrofosminwere radiolabelled with99mTc and the percentages ofthe RCP were determined. Five different methods were compared with the standard RCPtesting method (ITLC-SG, 2x20 cm): Whatman 3MM (1x10 cm) with acetone and dichloro-methane (method 1); Whatman 3MM (1x10 cm) with ethyl acetate (method 2); aluminumoxide-coated plastic thin-layer chromatography (TLC) plate (1x10 cm) and ethanol (method 3);Whatman 3MM (2x20 cm) with acetone and dichloro-methane (method 4); solid-phaseextraction method C18 cartridge (method 5).RESULTS:The average values of RCP were 95,30% ± 1,28% (method 1), 93,95 ± 0,61% (method2), 96,85% ± 0,93% (method 3), 92,94% ± 0,99% (method 4) and 96,25% ± 2,57% (method 5)(n=12 each), and 93,15% ± 1,13% for the standard method (n=19). There were statisticalsignificant differences in the values obtained for methods 1 (P=0,001), 3 (P=0,000) and 5(P=0,004), and there were no statistical significant differences in the values obtained formethods 2 (P=0,113) and 4 (P=0,327).CONCLUSION:From theresults obtained, methods 2 and 4 showed a higher correlation withthe standard method. Unlike method 4, method 2 is less time-consuming than the referencemethod and can overcome the problems associated with the solvent toxicity. The remainingmethods (1,3 and 5) tended to overestimate RCP value compared to the standard method.