Ermanno Vasca

Voltammetric and Spectroscopic Determination of Toxic Metals in Sediments and Sea Water of Salerno Gulf

In this present work the distribution of heavy metals in sea water and sediments of the Salerno Gulf is measured. The elements determined were Cu, Pb, Cd, Zn and Hg, employing, as instrumental techniques, either differential pulse anodic stripping voltammetry (DPASV) or graphite furnace atomic absorption spectroscopy (GFAAS). A comparison of the results of the two analytical techniques is also made. Mercury determination was carried out employing the cold vapour atomic absorption spectroscopy (CVAAS) technique, with SnCl2 as the reducing agent. The sample digestion was performed by a new procedure using concentrated suprapure H2SO4–K2Cr2O7 mixture. The accuracy and precision of the analytical procedure were evaluated employing Sea Water BCR-CRM 403 and Estuarine Sediment BCR-CRM 277 as reference materials. Accuracy, expressed as relative error e and precision, expressed as relative standard deviation sr, were in order of 2 to 5%. For both matrices, the detection limits, for all the elements, were in the range μg g-1 to ng g-1.

Modeling of radionuclides in natural fluids: synthesis and characterization of the Na4(UO2)2(OH)4(C2O4)2 complex

Abstract The coordination chemistry of dioxouranium(VI) with organic ligands may represent an useful model to describe the migration of radionuclides in natural fluids. A new dioxouranium(VI) ternary complex of formula Na 4 (UO 2 ) 2 (OH) 4 (C 2 O 4 ) 2 was precipitated at pH≅8. It was characterized by elemental analysis, ICP and IR spectroscopy, thermogravimetry (TG) and coupled TG–IR evolved gas analysis. Potentiometric measurements in the solution suggest that the equilibrium shifts from the prevalence of the (UO 2 ) 2 (OH) 2 (C 2 O 4 ) 4 6− complex to the [(UO 2 ) 2 (OH) 4 (C 2 O 4 ) 2 ] 4− complex before the formation of a solid phase.

Fluorogermanate(IV) equilibria in acid media

Abstract The equilibria between Ge(OH)4, HF and H+ ions in aqueous solution have been investigated, at 25°C in NaClO4 as well as in LiClO4 med The potentiometric data have been explained by the presence of GeF4, Ge(OH)F4−, GeF62−, HGeF6− and a minor complex to

A thermoanalytical study of unusual adrenaline complexes

A thermoanalytical study of unusual adrenaline coordination compounds with the divalent transition-metal ions Co(II), Ni(II) and Cu(II) is reported. The precipitated compounds were characterized by elemental analysis and by thermogravimetric (TG) analysis coupled to FTIR spectroscopy to analyze the evolved gases and make consistent the proposed decomposition steps. The complexes were obtained with metal/ligand molar ratios of 1:1 (base unit, only for the copper), 1:3 and 1:5.

Complex formation equilibria in the binary Zn2+–oxalate and In3+–oxalate systems

The complex formation equilibria between oxalate and Zn2+ as well as between oxalate and In3+ have been investigated through a potentiometric methodology at 25 °C in 1, 2 and 3 M NaClO4, by using both glass and metal amalgam electrodes. Owing to the low solubility of the Zn(II) and In(III) oxalates, the analytical concentration of the metal ions was forced to be kept below the 5 mM level: constant current coulometry has been used in order to prepare solutions containing the metal ion at very low but accurately known total concentration. At each ionic strength, the formation constants of the complexes ZnC2O4(aq), Zn(C2O4)22−, InC2O4+, In(C2O4)2− and In(C2O4)33− have been determined. By using the specific ion interaction theory the constants have been extrapolated at zero ionic strength. Thus relevant interaction coefficients have been obtained, which appear in the mathematical development of the theory. Solutions, containing InC2O4+ or In(C2O4)2− as the prevailing metal-containing species, were prepared on the basis of the thermodynamic parameters determined, and were analysed through electrospray mass spectrometry. The fragmentation of the In(C2O4)(H2O)2+ and In(C2O4)2− complexes detected produced respectively the InH2O+ and InC2O4− species of In(I).

On the Interaction Between Nicotine and Metal(II) Ions in Aqueous Solutions

A chemical investigation of the interaction mechanisms of nicotine with the metal(II) ions Pb

Complex Formation Between Lead(II) and Bromide Ions

^{2+}

New chelating agents for Cu(II), Fe(III), Al(III), and Zn(II) based on β-diketonate-3-substituted phthalide (isobenzofuranone) and isoindolinone

2+, Fe