DETERMINATION OF NET IONIC CHARGE ON TC-99M DTPA AND TC-99M EDTA BY A COLUMN ION-EXCHANGE METHOD

  • 1 January 1980
    • journal article
    • research article
    • Vol. 21  (4) , 354-360
Abstract
The net charge on a stable complex ion is conveniently measured at tracer levels by studies of ion-exchange equilibrium. Previous applications to radiopharmaceuticals have used a batch equilibrium method, but such measurements are affected by an radiochemical impurities present. Since Tc pharmaceuticals are often heterogeneous, a technique directly applicable to a mixture of different species is valuable. A column method to determine the net charge on the Tc-99m complex of diethylenetriaminepenta-acetic acid (DTPA) and on the principal component in a mixture of species formed by reducing pertechnetate in the presence of ethylenediaminetetra-acetic acid (EDTA) is presented. The net charge was calculated from the effect of eluent concentration on retention time. The net charge on Tc-DTPA was -2 at pH 4.6 and 7.0. The net charge on the Tc-EDTA complex at pH 7.0 was -2.