Potentiometric study of vitamin D 3 complexes with manganese(II), iron(II), iron(III) and zinc(II) in water—ethanol medium

• Published in: Journal of inorganic biochemistry Vol. 73; no. 3; pp. 167 - 172
• Main Authors: Merc⩽, A.L.R., Szpoganicz, B., Khan, M.A., Do Thanh, X., Bouet, G.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-03-1999
• Subjects: Potentiometry; Vitamen D 3 metallic complexes; Water-ethanol; Potentiometry; Water-ethanol; Vitamen D 3 metallic complexes
• ISSN: 0162-0134; 1873-3344
• DOI: 10.1016/S0162-0134(99)00014-8

Vitamin D
3 (LH) complexes with manganese(II), iron(II), iron(III) and zinc(II) were identified in water-ethanol medium (30/70). Their stability constants were determined at 298 K and at a constant ionic strength of 0.100 M using potentiometric methods. The computerisation of the experimental data showed the presence of ML (M = metal, L = deprotonated vitamin D
3) and ML
2 species in all cases; in addition, the ML
3 iron (III) complex was detected. The calculated overall stability constant
β for Mn
IIL, Fe
IIL, Fe
IIIL and Zn
IIL are, respectively, in logarithms, 12.4, 16.5, 28.5 and 16.5. Under the experimental conditions, the only protonated species MLH detected was with iron(III).