Analysis of 188Re-EDTMP complexes by HPLC and ultrafiltration

High performance liquid chromatography (anion-exchange, reversed-phase ion-pair and gel permeation chromatography) and ultrafiltration have been employed to analyze 188Re-ethylenediamine-N,N,N´,N´-tetrakis(methylenephosphonic acid) complexes ( 188Re-EDTMP), prepared from the tin chloride reduction or sodium borohydride reduction in the presence or absence of rhenium carrier. The HPLC analysis showed that the 188Re-EDTMP complexes were mixtures of components and the distribution of the components was dependent upon the total amount of rhenium present and the reducing agents (SnCl2, NaBH4). The ultrafiltration analysis showed that the distribution of nominal molecular weight of 188Re-EDTMP was dependent upon the presence of rhenium carrier and the reducing agents. In addition, it was found that the proportion of chemical species with bigger molecular weight in no-carrier-added 188Re(SnCl2)-EDTMP was larger than that in carrier-added 188Re(SnCl2)-EDTMP.