Assessment of cadmium and iron adsorption in sediment,employing a flow injection analysis system with on line filtration and detection by flame atomic absorption spectrometry and thermospray flame furnace atomic absorption spectrometry

This work presents an evaluation of iron and cadmium adsorption in sediment of the Furnas Hydroelectric Plant Reservatory located in Alfenas, Minas Gerais (Brazil). The metal determination was done employing a flow injection analysis (FIA) with an on-line filtering system. As detection techniques, flame atomic absorption spectrometry (FAAS) for iron and thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) for cadmium determinations were used. The developed methodology presented good limits of detection, being 190 μg L⁻¹ for iron and 1.36 μg L⁻¹ for cadmium, and high sampling frequency for both metals 144 and 60 readings h⁻¹ for iron and cadmium, respectively. Both metals obey the Langmuir model, with maximum adsorptive capacity of 0⋅169 mg g⁻¹ for iron and 7⋅991 mg g⁻¹ for cadmium. For iron, a pseudo-first-order kinetic model was obtained with a theoretical Q_e = 9⋅8355 mg g⁻¹ (experimental Q_e = 9⋅5432 mg  g⁻¹), while for cadmium, a pseudo-second-order kinetic model was obtained, with a theoretical Q_e = 0.3123 mg g⁻¹ (experimental Q_e = 0⋅3052 mg g⁻¹).     

Investigating the formation and the properties of monoalkyl carbonates in aqueous medium using capillary electrophoresis with capacitively coupled contactless conductivity detection

Although alkyl carbonic acids (ACAs) and their salts are referred to as instable species in aqueous medium, we demonstrate that a monoalkyl carbonate (MAC) can in fact be easily formed from bicarbonate and an alcohol even in the presence of a high amount of water. A CE system with two capacitively coupled contactless conductivity detectors (C?Ds) was used to obtain different parameters about these species and their reactions. Based on the mobilities obtained for a series of alcohols ranging from 1 to 5 carbons, the coefficients of diffusion and the hydrodynamic radii were calculated. When compared with the equivalent carboxylates, MACs have radii systematically smaller. Although the precise pK(a) values of the ACAs could not be obtained, because of the fast decomposition in acid medium, it was possible, for the first time, to show that they are below 4.0. This result suggests that the acidity of an ACA is quite similar to the first hydrogen of H?CO?. Using a new approach to indirectly calibrate the C?D, the kinetic constants and the equilibrium constants of formation were also obtained. The results suggest that the increase in the chain length makes the MACs less stable and more inert.     

Separation and determination of <Superscript>90</Superscript>Sr in low- and intermediate-level radioactive wastes using extraction chromatography and LSC

A methodology for the determination of ⁹⁰Sr in low- and intermediate-level radioactive wastes from nuclear power plants is presented in this work. It is a part of a methodology developed for the sequential radiochemical separation of radionuclides difficult-to-measure directly by gamma spectrometry in these radioactive wastes. The separation procedure was carried out using precipitation and extraction chromatography with Sr Resin, from Eichrom and the ⁹⁰Sr was measured by liquid scintillation counting (LSC). Optimum conditions for the pretreatment, separation and LSC measurements were determined using simulated samples, which were prepared using standard solutions and carriers. The procedure showed to be rapid and achieved a good chemical yield, in the range 60–90%, and a detection limit of 6.0 × 10⁻⁴ Bq g⁻¹. The method was also tested by participation in a national intercomparison program, with aqueous samples, with good agreement of results.     

Adsorption studies of Cd(II) onto Al2O3/Nb2O5 mixed oxide dispersed on silica matrix and its on-line preconcentration and determination by flame atomic absorption spectrometry

The present study describes the adsorption characteristic of Cd(II) onto Nb₂O₅/Al₂O₃ mixed oxide dispersed on silica matrix. The characterization of the adsorbent has been carried out by infrared spectroscopy (IR), scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), energy dispersive X-ray fluorescence analysis (EDXRF) and specific surface area (S_BET). From batch experiments, adsorption kinetic of Cd(II) was described by a pseudo-second-order kinetic model. The Langmuir linear isotherm fitted to the experimental adsorption isotherm very well, and the maximum adsorption capacity was found to be 17.88 mg g⁻¹. Using the effective material, a method for Cd(II) preconcentration at trace level was developed. The method was based on on-line adsorption of Cd(II) onto SiO₂/Al₂O₃/Nb₂O₅ at pH 8.64, in which the quantitative desorption occurs with 1.0 mol L⁻¹ hydrochloric acid towards FAAS detector. The experimental parameters related to the system were studied by means of multivariate analysis, using 2⁴ full factorial design and Doehlert matrix. The effect of SO₄²⁻, Cu²⁺, Zn²⁺ and Ni²⁺ foreign ions showed no interference at 1:100 analyte:interferent proportion. Under the most favorable experimental conditions, the preconcentration system provided a preconcentration factor of 18.4 times, consumption index of 1.08 mL, sample throughput of 14 h⁻¹, concentration efficiency of 4.35 min⁻¹, linear range from 5.0 up to 35.0 μg L⁻¹ and limits of detection and quantification of 0.19 and 0.65 μg L⁻¹ respectively. The feasibility of the proposed method for Cd(II) determination was assessed by analysis of water samples, cigarette sample and certified reference materials TORT-2 (Lobster hepatopancreas) and DOLT-4 (Dogfish liver).     

Synthesis and characterization of new porphyrin/4-quinolone conjugates

New porphyrin/4-quinolone conjugates were synthesized from the Suzuki-Miyaura coupling reaction of a β-borylated porphyrin with bromo-4-quinolones containing N-ethyl and N-d-ribofuranosyl substituents. The use of electrospray ionization tandem mass spectrometry showed important information about the fragmentation pathways of the new compounds. It was possible to distinguish between those compounds with the porphyrin moiety linked at the 6-position of the quinolone unit from their 7-substituted isomers. The new compounds showed to be good singlet oxygen generators.     

Thermochemical study of 2,5-dimethyl-3-furancarboxylic acid, 4,5-dimethyl-2-furaldehyde,and 3-acetyl-2,5-dimethylfuran

The standard (p° = 0.1 MPa) molar enthalpies of formation, in the gaseous state, at T = 298.15 K, for 2,5-dimethyl-3-furancarboxylic acid, 3-acetyl-2,5-dimethylfuran, and 4,5-dimethyl-2-furaldehyde were derived from the values of the standard molar enthalpies of formation, in the condensed phase, and the standard molar enthalpies of phase transition from the condensed to the gaseous state. The values of the standard molar enthalpies of formation of the compounds in the condensed phases were calculated from the measurements of the standard massic energies of combustion obtained by static bomb combustion calorimetry. The enthalpies of vaporization/sublimation were measured by Calvet high temperature microcalorimetry. For 2,5-dimethyl-3-furancarboxylic acid the standard enthalpy of sublimation was also calculated, by the application of the Clausius–Clapeyron equation, to the temperature dependence of the vapor pressures measured by the Knudsen effusion technique.     

108.

Experimental study on the thermochemistry of 3-nitrobenzophenone, 4-nitrobenzophenone and 3,3′-dinitrobenzophenone     

Manuel A.V. Ribeiro da Silva  Luísa M.P.F. Amaral  Rodrigo V. Ortiz 《The Journal of chemical thermodynamics》2011,43(4):546-551

     

109.

Direct monitoring of drug degradation by easy ambient sonic-spray ionization mass spectrometry: the case of enalapril     

Amaral PH  Fernandes R  Eberlin MN  Höehr NF 《Journal of mass spectrometry : JMS》2011,46(12):1269-1273

Using enalapril maleate as a test case, the ability of ambient mass spectrometry, namely, via easy ambient sonic‐spray ionization mass spectrometry (EASI‐MS), to perform direct monitoring of drug degradation has been tested. Two manufacturing processes were investigated (direct compression and wet granulation), and the formation of degradation products was measured via both EASI‐MS and high‐performance liquid chromatography with ultraviolet detection for a total period of 18 months. Both techniques provide comparable results, which indicate that direct analysis by ambient mass spectrometric techniques presents a viable alternative for drug degradation monitoring with superior simplicity, throughput, and reliability (no sample manipulation), and comparable quantitative results. In terms of qualitative monitoring, the full mass spectra with intact species provided by EASI‐MS allow for comprehensive monitoring of known and unknown (or unexpected) degradation products. Copyright © 2011 John Wiley & Sons, Ltd.     

110.

Leaf volatiles and secretory cells of Alpinia zerumbet (Pers.) Burtt et Smith (Zingiberaceae)     

Victório CP  Arruda Rdo C  Riehl CA  Lage CL 《Natural product research》2011,25(10):939-948

Plant leaves are commonly used in folk medicine and food industry. Their volatile composition is an important determinant in such applications. However, to properly assess the quality of volatiles, proper analytic tools must be utilised. Accordingly, the static headspace technique was used to evaluate the main volatiles emitted from in vitro-grown Alpinia zerumbet plants cultured with indole-3-acetic acid, thidiazuron, benzyladenine or kinetin, under standard physical conditions, as compared to those of field-grown donor plants. Although the leaf aroma of the donor plants was found to be a complex mixture, mainly consisting of sabinene, α and γ-terpinene, 1,8-cineole and caryophyllene, volatile analyses from most of the in vitro samples only revealed the presence of sabinene and caryophyllene. Many alkanes were found in the aromas after treating plantlets with cytokinins. Histochemical analysis of leaf sections was also carried out. Secretory cells found in the epidermis and mesophyll showed a strong positive reaction to lipophilic compounds using Oil red and Nile blue reagents. These findings demonstrated how in vitro conditions may alter the quality of volatiles in micropropagation systems, while leaf anatomy analysis revealed a large quantity of oil cells in the mesophyll as a constant feature responsible for the production of volatile compounds in both donor and in vitro-grown plants.     

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Direct monitoring of drug degradation by easy ambient sonic-spray ionization mass spectrometry: the case of enalapril

Using enalapril maleate as a test case, the ability of ambient mass spectrometry, namely, via easy ambient sonic‐spray ionization mass spectrometry (EASI‐MS), to perform direct monitoring of drug degradation has been tested. Two manufacturing processes were investigated (direct compression and wet granulation), and the formation of degradation products was measured via both EASI‐MS and high‐performance liquid chromatography with ultraviolet detection for a total period of 18 months. Both techniques provide comparable results, which indicate that direct analysis by ambient mass spectrometric techniques presents a viable alternative for drug degradation monitoring with superior simplicity, throughput, and reliability (no sample manipulation), and comparable quantitative results. In terms of qualitative monitoring, the full mass spectra with intact species provided by EASI‐MS allow for comprehensive monitoring of known and unknown (or unexpected) degradation products. Copyright © 2011 John Wiley & Sons, Ltd.     

Leaf volatiles and secretory cells of Alpinia zerumbet (Pers.) Burtt et Smith (Zingiberaceae)

Plant leaves are commonly used in folk medicine and food industry. Their volatile composition is an important determinant in such applications. However, to properly assess the quality of volatiles, proper analytic tools must be utilised. Accordingly, the static headspace technique was used to evaluate the main volatiles emitted from in vitro-grown Alpinia zerumbet plants cultured with indole-3-acetic acid, thidiazuron, benzyladenine or kinetin, under standard physical conditions, as compared to those of field-grown donor plants. Although the leaf aroma of the donor plants was found to be a complex mixture, mainly consisting of sabinene, α and γ-terpinene, 1,8-cineole and caryophyllene, volatile analyses from most of the in vitro samples only revealed the presence of sabinene and caryophyllene. Many alkanes were found in the aromas after treating plantlets with cytokinins. Histochemical analysis of leaf sections was also carried out. Secretory cells found in the epidermis and mesophyll showed a strong positive reaction to lipophilic compounds using Oil red and Nile blue reagents. These findings demonstrated how in vitro conditions may alter the quality of volatiles in micropropagation systems, while leaf anatomy analysis revealed a large quantity of oil cells in the mesophyll as a constant feature responsible for the production of volatile compounds in both donor and in vitro-grown plants.