Rapid determination of (90)Sr impurities in freshly "generator eluted"(90)Y for radiopharmaceutical preparation.

Abstract

(90)Y is one of the most useful radionuclides for radioimmunotherapeutic applications and has a half-life (t(1/2)=64.14h) suitable for most therapeutic applications, beta particles of high energy and decays to a stable daughter. It is significant that (90)Y is available conveniently and inexpensively from a radionuclide "generator" by decay of its parent, (90)Sr. Nevertheless, current and planned clinical applications with [(90)Y] 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 (90)Y solutions. In particular, for the development as a generator, we investigated the percentage of the radio-Sr in the first 8M HNO(3) eluate: in this fraction the concentration of (90)Sr 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 (90)Y in all the fractions containing "only" radio-Sr: (90)Y should not be present in these eluates. After the collection of beta(-) and gamma 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 4mL of Sr-resin which gave better results as a generator and a rapid QC method.