The simultaneous measurement method for the molar radioactivity, radiochemical purity, and chemical impurity of the [11C]choline injection

Background/Aims: [11C]Choline has been extensively used clinically for imaging prostate cancer [1]. [11C]Choline is prepared by 11C-methylation of [11C]methyl iodide and 2-dimethylaminoethanol (DMAE). It is important to determine accurately the quantity of DMAE in the final product. The most common method for the determination of the substance of [11C]choline or DMAE was by co-injection of carrier-choline or DMAE method, and by two separate analysis LC system and gas chromatography [2-4]. The quality control procedures for 11C-labeled radiopharmaceuticals is acquired rapid assessment due to short half-life radionuclide (about 20 min). Thus, we developed a rapid and simultaneous measurement method for the molar radioactivity, radiochemical purity, and chemical impurity of the [11C]choline injection using the radio-HPLC coupled with the corona-charged aerosol detector (CAD). Methods: The molar radioactivity, radiochemical purity, and chemical impurity (DMAE) of the [11C]choline injection was measured using the radio-HPLC-CAD with the post-column method. We also validated the measurement of choline and DMAE using this HPLC, and evaluated these parameters of the accuracy, precision, specificity, quantitation of limit, and linearity. Results: The molar radioactivity, radiochemical purity, and chemical impurity were over 130 GBq/μmol (over 0.1 μg/mL) at end of synthesis (EOS), over 95% at EOS, and less than 0.5 μg/mL of DMAE, respectively. In the validation, the percentages of recovery of choline and DMAE were within 100±5%. The RSD of choline and DMAE were less than 10%. Resolution between obtained choline and DMAE peak was over 1.5. The limit of quantitation of choline and DMAE was 0.1 and 0.5 μg/mL, respectively. The coefficient of correlation (R2) of choline (0.1-50 μg/mL) and DMAE (0.5-50 μg/mL) found to be >0.9999. Conclusions: We developed and optimized the simultaneous measurement method for the molar radioactivity, radiochemical purity, and chemical impurity of the [11C]choline injection using the radio-HPLC-CAD with the post-column method.References: [1] Giovacchini G, et al. Eur J Nucl Med Mol Imaging. 2017;44:1751-76. [2] Mishani E, et al. Nucl Med Biol. 2002;39:359-62. [3] Shao X, et al. Appl Radiat Isot. 2011;69:403-9. [4] Biasiotto G, et al. Med Chem. 2012;8:1182-9.\n(Abstracts are to be no more than 300 words. References, Title and authors details are not included in the word count. Abstracts should not contain bullet points.)12th World Congress of the World Federation of Nuclear Medicine and Biolog