Biomedical subjects

Carla Manfredi

Publications and source records attributed to Carla Manfredi.

2 recordsLinked to original sources

PubMed2005

On the hydrolysis of the dioxouranium(VI) ion in oxalate solutions.

The complex formation between the dioxouranium (VI) and the oxalate ions has been investigated by measuring the potential of a glass electrode, at 25.00 degrees C, in 1 and 3 M NaClO4, at lower acidities than 10(-4.5) M, in order to favour the formation of (mixed) ternary species. The upper limits of concentration of all the analytical parameters have been imposed by the modest solubility of Na2C2O4 in the ionic media. The experimental measurements at different ionic strengths have been treated by means of the computerised least square programme LETAGROP - ETITR. Ternary complexes of general composition (p, q, r) are formed according to reaction (1), in addition to the already reported binary complexes. pUO2(2+) + qH2O + rC2O4(2-) <==> (UO2)p(OH)q(C2O4)r(2p-q-2r)(+) + qH+ (1). The stoichiometric compositions of the ternary species are (1, 1, 1), (2, 4, 2), (2, 2, 4). Their formation constants, expressed in molality, obtained in the two ionic media, are listed below. [table: see text]. For reasons discussed in the present work in the last column only the value of the constant in 1 M ionic medium is reported for the species (2, 4, 2). Additional evidence on the stoichiometric composition of the species formed is afforded by the mass-spectrometric measurements, collected in solutions of known composition.

Adsorption↗

PubMed2002

Complex formation between phytic acid and divalent metal ions: a solution equilibria and solid state investigation.

An investigation on the complex formation equilibria between divalent metal ions Me (with Me=Mn, Co, Ni, Cu, Cd, and Pb) and phytic acid (H(12)L) is presented. Experiments were performed through a potentiometric methodology by measuring, at 25 degrees C, the proton and, in some cases (Cu(2+), Cd(2+), and Pb(2+)), also the metal ion activity at equilibrium in solutions containing, besides the metal and the ligand, 3 M NaClO(4) as the ionic medium. Unhydrolyzed solutions of the metal ion at millimolar concentration levels were titrated with solutions of about 10 mM sodium phytate, until the formation of a solid phase took place (always at pH approximately 2.5, except in the case of Cu(2+), which formed soluble complexes up to pH approximately 3.3). Coulometry was employed to produce very dilute solutions of either Cu(2+), Cd(2+), or Pb(2+) of accurately known composition. The emf data were explained by assuming, in the acidity interval explored, the formation of the complexes of general stoichiometry MeH(5)L(5-) and Me(2)H(3)L(5-). Coordination compounds in the solid state were also synthesized and characterized by elemental analysis, thermal analysis, and ICP spectroscopy. The solids had a general stoichiometry Me(6)H (t)LCl (t). x H(2)O, with the following t and x values for each metal investigated: Me ( t; x) = Mn (4; 2); Co (4; 2); Ni (4; 2); Cu (2; 2.5); Zn (2; 1); Sn (6; 6).

Journal Article↗