title: Speciation in the aqueous H+/H2VO4-/H2O2/picolinate system relevant to diabetes research.
abstract: A detailed study of the quaternary aqueous H+/H2VO4-/H2O2/picolinate (Pi-) system has been performed at 25 degrees C in 0.150 M Na(Cl) medium using quantitative 51 V NMR (500 MHz) and potentiometric data (glass electrode). In the ternary H+/H2VO4-/Pi- system, six complexes have been found in the pH region 1-10. In the quaternary H+/H2VO4-/H2O2/Pi- system, eight additional complexes have been found. Generally, equilibria are fast in both systems. The rate of peroxide decomposition depends on the species in solution. Chemical shifts, compositions and formation constants for the species are given. Equilibrium conditions and the fit of the model to the experimental data are illustrated in distribution diagrams. Possible formation of mixed ligand species with imidazole, lactic acid and citric acid have been investigated and ruled out under the same experimental conditions. Structural proposals are given, based on 1)C NMR data and available crystal structures.
authors.affiliation: Department of Chemistry, Inorganic Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Ingegärd
authors.initials: I
authors.lastname: Andersson
authors.forename: András
authors.initials: A
authors.lastname: Gorzsás
authors.forename: Lage
authors.initials: L
authors.lastname: Pettersson
mesh_terms: D002247:Carbon Isotopes; D003920:Diabetes Mellitus / Q000378:metabolism; D004355:Drug Stability; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010848:Picolinic Acids / Q000737:chemistry*; D011199:Potentiometry / Q000379:methods; D014639:Vanadium / Q000737:chemistry*; D017968:Vanadium Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D008024:Ligands; D010848:Picolinic Acids; D017968:Vanadium Compounds; D014639:Vanadium; D014867:Water; D006861:Hydrogen Peroxide