ISSN:
1588-2780
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Energy, Environment Protection, Nuclear Power Engineering
Notes:
Abstract DPD (2,3-dicarboxypropane-1,1-diphosphonic acid) forms two complexes with99Tc, previously reduced by Sn(II): with λmax at 410 nm (pH 3–7), and at 515 nm (pH 5–9.6). By Job's method, formation of complexes with DPD:Tc molar ratios of 2∶1 and 2∶3 was found in acidic medium (pH=3). In order to determine the valence states of Tc in the complex, taking into account that formation of99Tc-DPD complex does not occur in absence of a reducing agent (here divalent tin), the redox potentiometric titration method was applied. In acidic medium (pH=3), Tc was reduced to Tc(III) by Sn(II), while in presence of DPD to Tc(IV). In strongly alkaline medium (pH〉13) the situation was reverse: Tc(III) was formed in the DPD complex, while Tc(IV) in absence of the ligand. In slightly alkaline medium (pH about 8) in both cases (with or without the ligand) TC(III) was obtained at the titration end point. This phenomenon can explain the dependence of99mTc-radiopharmaceutical complexes on the sequence of reagent addition. These conclusions are very important for99mTc-DPD radiopharmaceutical solutions used in diagnostic nuclear medicine for skeletal imaging.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02043028
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