Alternative chromatographic system for the quality control of lipophilic technetium-99m radiopharmaceuticals such as [99mTc(MIBI)6]+

Knowledge of the radiochemical purity of radiopharmaceuticals is mandatory and can beevaluated by several methods and techniques. Planar chromatography is the techniquenormally employed in nuclear medicine since it is simple, rapid and usually of lowcost. There is no standard system for the chromatographic technique, but price,separation efficiency and short time for execution must be considered. We havestudied an alternative system using common chromatographic stationary phase andalcohol or alcohol:chloroform mixtures as the mobile phase, using the lipophilicradiopharmaceutical [^99mTc(MIBI)₆]⁺ as a model.Whatman 1 modified phase paper and absolute ethanol, Whatman 1 paper andmethanol:chloroform (25:75), Whatman 3MM paper and ethanol:chloroform (25:75), andthe more expensive ITLC-SG and 1-propanol:chloroform (10:90) were suitable systemsfor the direct determination of radiochemical purity of[^99mTc(MIBI)₆]⁺ since impurities suchas^99mTc-reduced-hydrolyzed (RH),^99mTcO₄^- and [^99mTc(cysteine)₂]^-complex werecompletely separated from the radiopharmaceutical, which moved toward the front ofchromatographic systems while impurities were retained at the origin. The timerequired for analysis was 4 to 15 min, which is appropriate for nuclear medicineroutines.