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Potentiometric Study of Holmium Complexes with EDTMP

Milena Ernestová ; Department of Analytical Chemistry, Institute of Chemical Technology, Technická 5, 166 28 Prague 6, Czech Republic
Vefra Jedináková-Křížová ; Department of Analytical Chemistry, Institute of Chemical Technology, Technická 5, 166 28 Prague 6, Czech Republic
Petr Vanfura ; Department of Analytical Chemistry, Institute of Chemical Technology, Technická 5, 166 28 Prague 6, Czech Republic

Abstract

Within the study of 166Ho-complexes as potential radiopharmaceutical agents, stability constants of those with EDTMP (ethylenediamine-N,N,N´,N´-tetra(methylenephosphonate)) were calculated by the computer program LETAGROP Etitr using data from potentiometric titrations measured at 25 °C in 0.1 M NaCl. The following values were obtained for stability constants of Ho-EDTMP complexes Ho(OH)L6–, HoL5–, HHoL4–, H₂HoL3–, H₃HoL2– and H₄HoL–: log β = 9.31, 20.22, 28.14, 34.55, 39.89, 45.05, respectively. Diagram of the complex speciation dependence on pH shows that complex forms HHoL4– and H₂HoL3– are characteristic of the pH range 6–8, which is adequate for their application into the human body.

Keywords

holmium; EDTMP (ethylenediamine-N,N,N',N'-tetra(methylenephosphonate); potentiometry

Hrčak ID:

103018

URI

https://hrcak.srce.hr/103018

Publication date:

30.11.2004.

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