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Gallium ［68Ga］ is an important positron-emitting radionuclide in PET imaging radiopharmaceuticals. In order to ensure that the quality of gallium ［68Ga］ solution, a key raw material of gallium ［68Ga］ radiopharmaceuticals, meets the requirements of high labeling efficiency and safety, a detailed study on impurities in gallium ［68Ga］ solution from the generator was carried out, analytical method for impurity detection was developed and the validation of the methodology was completed. To control radiochemical impurities, radioactive thin-layer chromatography (Radio-TLC) method was used. The effects of key variables such as mobile phase, pH of the mobile phase, and system suitability solution on the test results were studied. After method optimization, iTLC-SG was determined to be the stationary phase, methanol-1 mol/L ammonium acetate (1∶1, V/V, ammonium acetate pH=2.8±0.2) as the mobile phase. In order to control elemental impurities, twelve elements including Fe, Ni, Zn, Sb, Pb, Li, V, Co, Cu, As, Cd, and Hg were determined by inductively coupled plasma mass spectrometry (ICP-MS) method. The radionuclide purity was determined by high-purity germanium (HPGe) γ spectroscopy, and the γ nuclide impurities such as 68Ge were controlled. Combined with the properties of the samples and the characteristics of each analytical method, the established analytical methods were validated. The validation included system suitability and resolution, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, durability, etc. These validated methods were used to determine impurities in gallium-［68Ga］ chloride solutions. The impurity test results of gallium-［68Ga］ chloride solution show that the Rf of 68Ga3+ is ≤0.2, and its radiochemical purity is 99.04%±0.35% (n=3). Its iron content is ≤0.5 μg/GBq, zinc content is ≤0.1 μg/GBq, and other elements do not exceed 30% of the PDE limits. Gallium ［68Ga］ radionuclide purity is more than 99.9%, other γ nuclide impurities are not detected at the first detection. 24 hours later, germanium ［68Ge］ breakthrough and other γ nuclide impurity content is 0.000 19%±0.000 05% (n=3). The results show that the established analytical methods can accurately determine the impurity of gallium-［68Ga］ chloride solution and effectively control its quality. The impurity content is lower than the limit required by European Pharmacopoeia (EP10.0). The successfully established detection method for impurities of gallium-［68Ga］ chloride solution provides a reference for the impurity control of medical radionuclides and the establishment of quality standards. |
