Improving the radiochemical purity determination of 123I-labeled metaiodobenzylguanidine

Abstract

The HPLC method originally applied at the Nuclear Engineering Institute (IEN) for the radiochemical purity determination of 123iodine labeled m-iodobenzylguanidine (123I-mIBG) takes 18.5 min. The final product release also depends on this result, and to facilitate this stage, we aimed to decrease this analysis time. We also intended to use fewer toxic compounds, if feasible. The optimization approach used herein was a combination of factorial and mixture designs to study simultaneously the selected variables. Analysis time, resolution and chromatograms aspect were the measured responses. The qualitative analysis of these responses provided the best chromatographic separation conditions that were 52 mM KH2PO4 in a solution of ethanol and water (1:1), applying a flow rate of 0.50 mL min−1 and C18 column (4.6 × 250 mm, 5 μm). These optimum conditions not only decreased the analysis time in 61 %, but also allowed the reduction of mobile phase toxicity. To assure reliable data, method validation was performed for these conditions. The method has proved its specificity, the detection limit found was 3.70 × 10−4 MBq mL−1 and the quantification limit has corresponded to 1.11 × 10−3 MBq mL−1. Repeatability and intermediate precision has not exceeded 3 and 5 %, respectively, and the accuracy has matched the interval of 95–105 %. This new method has been routinely applied in the radiochemical purity determination of 123I-mIBG at IEN.