Rapid determination of 90Sr impurities in freshly “generator eluted” 90Y for radiopharmaceutical preparation

90Y is one of the most useful radionuclides for radioimmunotherapeutic applications and has a half-life (t1/2=64.14 h) suitable for most therapeutic applications, beta particles of high energy and decays to a stable daughter. It is significant that 90Y is available conveniently and inexpensively from a radionuclide “generator” by decay of its parent, 90Sr. Nevertheless, current and planned clinical applications with [90Y] labelled compounds employ activity levels that cannot be readily obtained from an in-house generator, but from commercial sources. We have evaluated Eichrom's Sr-resin, either as an “in-house” generator or as a fast QC method for analysis of 90Y solutions.In particular, for the development as a generator, we investigated the percentage of the radio-Sr in the first 8 M HNO3 eluate: in this fraction the concentration of 90Sr must be smaller than 10−5% (recommendations of the International Commission on Radiological Protection). For evaluation as a rapid QC method, we analyzed the concentration of 90Y in all the fractions containing “only” radio-Sr: 90Y should not be present in these eluates. After the collection of β− and γ spectra and analysis of them, we concluded that commercial Sr-resin minicolumn cannot give us the results expected; we developed an in-house system loaded with 4 mL of Sr-resin which gave better results as a generator and a rapid QC method.