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Thermal analyses of coordination compounds

II. Thermal decomposition of palladium complexes with triphenylphosphine, triphenylarsine and triphenylstibine

Journal of Thermal Analysis and Calorimetry
Authors: R. Barbiéri, C. Belatto, and A. Massabni

Abstract  

The compounds [PdCl2L2] and [PdL4] (L=PPh3, AsPh3, SbP3) were studied by thermogra-vimetric and differential thermal analyses in air. The residues of thermal decomposition consist of metallic palladium, except in the case of the complexes containing SbPh3, when the residues are palladium and antimony mixtures in appropriate proportions with respect to the stoichiometry of the related complexes.

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Abstract  

The compounds [(LR2Sn)2O] {R=CH3 (Me), n-C4H9(Bn); L=C6H5CH(OH)COO}were studied by thermogravimetric and differential scanning calorimetry in a dynamic atmosphere of helium. The thermal decomposition mechanisms are similar for both compounds and occur in two consecutive steps. The TG curves of the complexes suggest the liberation of the ligand L in the first step, with probable formation of a tin oxide R2SnO intermediate. At the end of the second step free tin is obtained in accordance with the stoichiometry of the related compounds. An inverse relation betweenΔH fusion and solubility of the compounds suggests a polymeric structure for the compound with Bn ligand in relation to the compound with M ligand.

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Acta Alimentaria
Authors: A. Vásquez García, S.H. Gomes de Sá, G. de Sousa Silva, J.E. Mejia Ballesteros, E. Barbieri, R.L. Moro de Sousa, A.M. Fernandes, and M. Mitsui Kushida

The objective of this study was to evaluate the microbiological quality of oysters and mussels grown in Cananéia, Brazil, by analysing mesophiles, psychrothophic bacteria, moulds and yeasts, Staphylococcus aureus, and Salmonella spp., and to compare the efficiency of Compact Dry EC method and the conventional method for counting of total coliforms and Escherichia coli. The microbial analysis showed that the mean values of mesophilic counts were 3.14±0.81 log CFU g−1 for oysters and 3.92±0.90 for mussels; the mean values of psychrophilic counts were 2.78±0.75 log CFU g−1 for oysters and 3.22±0.75 log CFU g−1 for mussels; the mean values of mould and yeast counts were 3.70±0.58 log CFU g−1 for oysters and 3.33±0.81 log CFU g−1 for mussels. Salmonella spp. did not present positive results, and the maximal count of Staphylococcus aureus was 1.7 log CFU g−1, therefore, within the limits established in the legislation. The correlation coefficients between the Compact Dry EC method and conventional method were >0.87 for total coliform and E. coli counts for both types of shellfish. The data in this study show that the Compact Dry EC method is an acceptable alternative to conventional methods for enumeration of total coliforms and E. coli in shellfish.

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