Intricacies of the Determination of the Radiochemical Purity of 68Ga Preparations: Possibility of Sorption of Ionic 68Ga Species on Reversed-Phase Columns

The results of studying ⁶⁸Ga radiopharmaceuticals using various TLC and HPLC procedures are compared. The data obtained reliably show that a part of ⁶⁸Ga ionic species are irreversibly (under definite conditions) sorbed onto chromatographic columns packed with С18 reversed phase. The loss of ⁶⁸Ga ionic species in the analysis can reach 90%. The ⁶⁸Ga loss increases with an increase in pH of the preparation. At pH 2.5–3.0, the total loss of ⁶⁸Ga ionic species on the chromatographic column does not exceed 15%. At pH 4.0, it is 65 ± 7% on the average, and at pH 6.0 it reaches 87 ± 8%. This effect should be taken into account in analysis of any ⁶⁸Ga radiopharmaceuticals.