Solution equilibrium studies on Cu(2+)-L(1)-L(2) ternary systems have been performed by pH-potentiometry, UV-Vis spectrophotometry and EPR methods {where L(1) corresponds to a polyamine such as ethylenediamine (en), diethylenetriamine (dien), N,N,N',N',N″-pentamethyldiethylenetriamine (Me(5)dien)} and L(2) denotes 2-aminoethylphosphonic acid (β-alaninephosphonic acid)}. The results suggest the ...

Glutarimidedioxime (H(2)A), a cyclic imide dioxime ligand that has implications in sequestering uranium from seawater, forms strong tridentate complexes with UO(2)(2+). The stability constants and the enthalpies of complexation for five U(VI) complexes were measured by potentiometry and microcalorimetry. The crystal structure of the 1 : 2 metal-ligand complex, UO(2)(HA)(2)·H(2)O, was determined...

vidual chemical element between different chemical species or groups of species [1]. In natural aquatic systems it reflects the chemical complexity of these media. Substantial progress has been made over recent years in chemical speciation and in the understanding of metal interactions with aquatic organisms, which are crucial issues owing to their intimate relationships with bioavailability an...

OBJECTIVES To evaluate in vitro the endogenous pH, titratable acidity and total soluble solid content (TSSC) of mouthwashes available in the Brazilian market. METHODS The study sample was composed of 10 commercial brands of mouthwashes based on different active ingredients: Cepacol(R), Clinerize(R), Equate(R), Listerine Cool Citrus(R), Oral-B(R), Periogard(R), Peroxyl(R), Plax Overnight(R), P...

The synthesis of ligand L(T)H8, based on a thiophene framework containing two bis(aminomethyldiphosphonate) functions in the ortho position to the central sulfur atom, is described, together with the characterization of the intermediate compounds. The physico-chemical properties of the ligand were first studied by means of potentiometry and UV-Vis absorption spectrophotometric titrations to det...

Diglycyl-L-histidine is a peptide molecule designed to mimic the specific Cu(II) transport site of human albumin. The equilibria involved in the Cu(II)-diglycyl-L-histidine system have been investigated by analytical potentiometry in aqueous solution (0.15 M NaCl, 25’). The synthetic peptide molecule bound Cu(I1) exclusively as a 1: I complex in the pH range of 6.50 to 11.00. The results furthe...

Ethylammonium nitrate (EAN) is composed of C(2)H(5)NH(3)(+) and NO(3)(-) ions, which behave as an acid and a base, respectively. The ionic liquid thus involves small amounts of C(2)H(5)NH(2) and HNO(3) molecules owing to proton transfer from C(2)H(5)NH(3)(+) to NO(3)(-). The equilibrium constant K(s) (= [C(2)H(5)NH(2)][HNO(3)]), which corresponds to the autoprotolysis constant of water, was obt...

Sodium was determined by flame photometry and by direct potentiometry in 56 serum or plasma samples from 24 patients with multiple myeloma or macroglobulinemia. We observed differences between the two techniques as large as 17 mmol/L (12%). The flame-photometric values decreased relative to the direct-potentiometric values as protein increased or water content decreased. Moreover, the two sodiu...

Electrochemical analysis allows in situ characterization of solid oxide electrochemical cells (SOCs) under operating conditions. However, the SOCs that have been analyzed in this way have ill-defined or uncommon microstructures in terms of porosity and tortuosity. Therefore, the nano-scale characterization of SOCs with respect to three-phase boundaries has been hindered. We introduce novel in s...