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Abstract  

A novel solid complex, formulated as Ho(PDC)3 (o-phen), has been obtained from the reaction of hydrate holmium chloride, ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phenH2O) in absolute ethanol, which was characterized by elemental analysis, TG-DTG and IR spectrum. The enthalpy change of the reaction of complex formation from a solution of the reagents, Δr H m θ (sol), and the molar heat capacity of the complex, c m, were determined as being –19.1610.051 kJ mol–1 and 79.2641.218 J mol–1 K–1 at 298.15 K by using an RD-496 III heat conduction microcalorimeter. The enthalpy change of complex formation from the reaction of the reagents in the solid phase, Δr H m θ(s), was calculated as being (23.9810.339) kJ mol–1 on the basis of an appropriate thermochemical cycle and other auxiliary thermodynamic data. The thermodynamics of reaction of formation of the complex was investigated by the reaction in solution at the temperature range of 292.15–301.15 K. The constant-volume combustion energy of the complex, Δc U, was determined as being –16788.467.74 kJ mol–1 by an RBC-II type rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, Δc H m θ, and standard enthalpy of formation, Δf H m θ, were calculated to be –16803.957.74 and –1115.428.94 kJ mol–1, respectively.

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Abstract  

A solid complex Eu(C5H8NS2)3(C12H8N2) has been obtained from reaction of hydrous europium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen⋅H2O) in absolute ethanol. IR spectrum of the complex indicated that Eu3+ in the complex coordinated with sulfur atoms from the APDC and nitrogen atoms from the o-phen. TG-DTG investigation provided the evidence that the title complex was decomposed into EuS. The enthalpy change of the reaction of formation of the complex in ethanol, Δr H m θ(l), as –22.2140.081 kJ mol–1, and the molar heat capacity of the complex, c m, as 61.6760.651 J mol–1 K–1, at 298.15 K were determined by an RD-496 III type microcalorimeter. The enthalpy change of the reaction of formation of the complex in solid, Δr H m θ(s), was calculated as 54.5270.314 kJ mol–1 through a thermochemistry cycle. Based on the thermodynamics and kinetics on the reaction of formation of the complex in ethanol at different temperatures, fundamental parameters, including the activation enthalpy (ΔH θ), the activation entropy (ΔS θ), the activation free energy (ΔG θ), the apparent reaction rate constant (k), the apparent activation energy (E), the pre-exponential constant (A) and the reaction order (n), were obtained. The constant-volume combustion energy of the complex, Δc U, was determined as –16937.889.79 kJ mol–1 by an RBC-II type rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, Δc H m θ, and standard enthalpy of formation, Δf H m θ, were calculated to be –16953.379.79 and –1708.2310.69 kJ mol–1, respectively.

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Abstract  

Ten rum (aguardente) samples commercialized in Piracicaba region, São Paulo State, Brazil Southeast, were analysed by energy-dispersive X-ray fluorescence (EDXRF) using ammonium pyrrolidinedithiocarbamate (APDC) preconcentration in order to determine Fe, Cu and Zn concentrations. The effect of sucrose (2%) was also studied in this methodology, using a multielemental standard solution (40% ethanol). Copper concentrations in two samples were higher than the value allowed by Brazilian law. Limits of detection for these elements were in the ng.ml-1 range.

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Abstract  

Neutron activation analysis (NAA) methods were employed for the determination of total arsenic, and water soluble As(III) and As(V) compounds in freshwater fish/shellfish and plant samples from Southern Thailand. Total arsenic concentrations varied from 0.05 to 425 mg kg−1. Water soluble arsenic species were separated by solvent extraction using ammonium pyrrolidinedithiocarbamate (APDC)/methylisobutylketone (MIBK) followed by NAA. The water soluble As(III) and As(V) levels varied from 0.07 to 26.4 and 0.03 to 22.9 mg kg−1, respectively. The As(III) and As(V) detection limits were 0.007 for fish/shellfish, 0.005 for As(III) and 0.006 mg kg−1 for As(V) in plants. This separation method allows for the determination of water soluble As(III) and As(V) using commonly available and inexpensive laboratory equipment and chemicals, which can be coupled to a variety of quantification techniques.

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Abstract  

Substoichiometric extraction of chromium with tetraphenylarsonium chloride (TPACl), tri-n-octylamine (TNOA), diethylammonium diethyldithiocarbamate (DDDC) and ammonium pyrrolidinedithiocarbamate (APDC) was examined in detail. Chromium can be extracted substoichiometrically in a pH range, which is 1.1–2.6 for the TPACl compound, 0.6–2.3 for the TNOA compound, 5.1–6.4 for the DDCC chelate and 3.9–4.9 for the APDC chelate. Chromium in high-purity calcium carbonate, Orchard Leaves (NBS SRM-1571) and Brewers Yeast (NBS SRM-1569) was determined by neutron activation analysis combined with substoichiometric extraction by DDDC and APDC. The values of 2.0±0.02 ppm and 2.6±0.2 ppm were obtained for Brewers Yeast and Orchard Leaves, respectively. These values were in good agreement with the values reported by NBS. The reaction mechanism and the reaction ratio between hexavalent chromium and dithiocarbamate were also discussed.

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