Methods for the Determination of Transition Metal Impurities in Cyclotron-Produced Radiometals

Viktória Forgács,Dániel Szücs,Dezső Szikra,Anikó Fekete,Barbara Gyuricza,György Trencsényi

doi:10.3390/ph15020147

Abstract

Cyclotron-produced radiometals must be separated from the irradiated target and purified from other metal impurities, which could interfere with the radiolabeling process. We compared different chromatographic and colorimetric methods to determine the amount of transition metals in radioactive samples. Besides commercially available colorimetric tests, 4-(2-pyridylazo)resorcinol and xylenol orange were used as a non-selective metal reagents, forming water-soluble chelates with most of the transition metals immediately. We compared the applicability of pre- and post-column derivatization, as well as colorimetric determination without separation. The studied chromatographic and colorimetric analyses are not suitable to completely replace atomic spectroscopic techniques for the determination of metal contaminants in radioactive samples, but they may play an important role in the development of methods for the purification of radiometals and in their routine quality control.

Highlights

Academic Editor: Gerald ReischlWith the increasing application of cyclotron-produced radiometals, the determination of non-radioactive metal impurities is becoming more important, since they can reduce the radiolabeling efficiency
The simple labeling chemistry of gallium-68 facilitates the development of new specific radiopharmaceuticals based on receptor–ligand interaction for different diseases and the broadening application of receptor-targeted radionuclide therapy necessitates the use of 68 Ga-labeled tracers for therapy monitoring and dosimetry
We investigated the use of PAR- and xylenol orange reagents without separation to determine the metal content of the radioactive samples

Summary

Introduction

With the increasing application of cyclotron-produced radiometals, the determination of non-radioactive metal impurities is becoming more important, since they can reduce the radiolabeling efficiency. The positron-emitting gallium-68 isotope is obtained mainly from 68 Ge/68 Ga generators for the synthesis of radiopharmaceuticals, but the recent increase of generator price and availability issues have motivated the development of different cyclotron production methods using liquid- [1,2,3] and solid targets [4,5,6,7,8,9,10,11]. The simple labeling chemistry of gallium-68 facilitates the development of new specific radiopharmaceuticals based on receptor–ligand interaction for different diseases and the broadening application of receptor-targeted radionuclide therapy necessitates the use of 68 Ga-labeled tracers for therapy monitoring and dosimetry

Methods

Results

Conclusion