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1.
J. L. Souza A. F. Santos L. Polese Marisa S. Crespi C. A. Ribeiro 《Journal of Thermal Analysis and Calorimetry》2007,87(3):673-677
Poly(3-hydroxybutyrate), PHB has been structurally
modified through reaction with maleic anhydride, MA. Transesterification reaction
was carried out fixing the PHB and MA and besides time and temperature the
concentration of the triethylamine (used as catalyst) was changed. Glass transition,
melting and crystallization temperature obtained from DSC curves and thermal
degradation temperatures obtained from TG traces were used to evaluate the
influence of the reaction conditions on the modification of PHB according
to factorial design. On the base of the results the optimum conditions are
to perform the PHB modification reaction with MA reaction at 110°C for
1 h with 5% v/v triethylamine. 相似文献
2.
A new utility for multipurpose analysis, SOLVERSTAT, taking advantage of the versatility of spreadsheets is here described. By means of this tool advanced statistical tests have introduced in Microsoft Excel Solver thus allowing regression diagnostic and discrimination between different models. The utility is here applied to the determination, by UV-Vis spectroscopy, of the stability constant for the uptake of molecular dioxygen by the 1:2 complex of Co(II) with N,N′-dimethylethylenediamine (dmen) in the aprotic solvent dimethylsulfoxide (dmso) at 298 K and in a medium adjusted to 0.1 mol dm−3 with Et4NClO4. The reliability of the model and parameters obtained are discussed and the results compared with those obtained by Dynafit, a different software package, and by independent voltammetric measurements. The validity of SOLVERSTAT has been also examined applying it to the discrimination between different models already discussed in the literature. 相似文献
3.
Polese Pierluigi Tolazzi Marilena Melchior Andrea 《Journal of Thermal Analysis and Calorimetry》2018,132(2):1317-1323
Journal of Thermal Analysis and Calorimetry - The pyrolysis characteristics and kinetics of lignocellulosic biomass (cotton stalk) and seaweed (Gracilaria lemaneiformis) were studied comparatively.... 相似文献
4.
Methods for determination of hexachlorobenzene and pentachlorophenol in soil samples 总被引:2,自引:0,他引:2
The efficiency of methods for the determination of hexachlorobenzene (HCB) and pentachlorophenol (PCP) in soil samples was evaluated. An on-line method was applied for HCB determination. Soil samples were transferred to chromatographic columns prepacked with alumina. The HCB elution was processed with n-hexane. The PCP was extracted from soil samples with n-hexane-acetone in an ultrasonic bath. After re-extraction with K(2)CO(3) solution PCP was acetylated with acetic anhydride. The pentachlorophenyl acetate derivative was then extracted with n-hexane. The HCB and PCP derivative were analyzed by gas chromatography with electron capture detection (GC-ECD). Mean recoveries obtained from soil samples fortified at levels of 0.5; 4 and 20 ng g(-1), ranged from 91 to 100% for HCB, and for PCP, at levels of 10; 40 and 200 ng g(-1), ranged from 88 to 101%. These results demonstrated the efficiency of the proposed methods. 相似文献
5.
Polese L Minelli EV Jardim EF Ribeiro ML 《Analytical and bioanalytical chemistry》1996,354(4):474-476
A small-scale method was developed for the simultaneous determination of gamma-HCH, heptachlor, aldrin, dicofol, mirex, endosulfan I, endosulfan II and endosulfan sulphate in soil. The extraction and clean-up steps were combined into one step by transferring soil samples to chromatographic columns prepacked with neutral alumina. The pesticides elution was processed with n-hexane : dichloromethane (7 : 3) and the concentrated eluate was analysed using gas-liquid chromatography with electron capture detection. Analyses of the "in vitro" fortified samples with the selected pesticides were performed at three different levels. Mean recoveries for aldrin, gamma-HCH and heptachlor, at levels of 2, 10 and 20 ng/g, ranged from 71 to 87%; for dicofol, at levels of 8, 40 and 80 ng/g, ranged from 97 to 103%; for endosulfan I and II, at levels of 5, 25 and 50 ng/g, ranged from 88 to 96%; for mirex, at levels of 6, 30 and 60 ng/g, ranged from 86 to 110%; and for endosulfan sulphate, at levels of 15, 75 and 150 ng/g, ranged from 93 to 104%. The method can be used for rapid determination of these pesticides in soil. 相似文献
6.
Summary A simple and efficient method is described for the determination of fenpropathrin in oranges, pears, apples and strawberries.
The procedure is based on the extraction of each homogenized fruit sample with hexane:acetone (1∶1, v/v) mixture, followed
by a cleanup technique on a column packed with florisil, using a hexane:ethyl ether (7∶3, v/v) mixture, and gas chromatographic
analysis with electron capture detection (ECD). The fortification levels (0.5;1.0;2.0 mg kg−1) were selected according to the maximum residue limits (MRLs) established for fenpropathrin by Brazilian legislation. Mean
recoveries from five replicates of fortified fruit samples ranged from 83 % to 98%, with coefficients of variation from 1.4
to 13.5 and detection limits varying from 0.1 to 0.2 mg kg−1. 相似文献
7.
Experimental Mechanics - The American standard ASTM E837 presents a standard procedure to determine residual stresses in isotropic materials using the incremental hole drilling technique (IHD). The... 相似文献
8.
Silvia Del Piero Rosalisa Fedele Andrea Melchior Pierluigi Polese Roberto Portanova Marilena Tolazzi 《Journal of solution chemistry》2008,37(4):543-551
The thermodynamic functions of the complexation of Ag(I) by the tripodal ligands, tris(2-(methylamino)ethyl)amine (Me3tren) and tris(2-(dimethylamino)ethyl)amine (Me6tren) (L), are determined in dimethyl sulfoxide (DMSO) by potentiometric and calorimetric techniques at 298.0 K and 0.1 mol⋅dm−3 ionic strength (Et4NClO4). A comparison is made between previous data concerning Ag(I) complex formation with the non-alkylated tripodal 2,2′,2″-triaminotriethylamine
(tren), in order to analyze the influence of N-methylation on this type of branched donor, and with those relative to the
linear triethylenetetramine (trien) and 1,1,4,7,10,10-hexamethyltriethylenetetramine (Me6trien). The results are discussed taking into account different σ-donating properties, geometric arrangement of the ligands, steric repulsions and solvation effects. 相似文献
9.
Sandro Navickiene Marta H. Kato Luciana Polese E. V. Minelli Maria L. Ribeiro 《Analytical and bioanalytical chemistry》1998,360(2):252-255
A rapid and economical method is described for the determination of deltamethrin in wheat, rice, peanuts and corn. It is
based on simultaneous extraction and clean-up on a column packed with alumina and silica gel using n-hexane-ethyl ether (8:2,
v/v), followed by a derivatization step and gas-chromatographic analysis. Recoveries from fortified cereal and peanut samples
were determined at four concentration levels and ranged from 73 to 109%. The detection limits were 0.01 to 0.03 mg/ kg. This
method simplifies the traditional procedures in terms of sample size, solvent consumption and analysis time.
Received: 25 March 1997 / Revised: 3 June 1997 / Accepted: 4 June 1997 相似文献
10.
Sandro Navickiene Marta H. Kato Luciana Polese E. V. Minelli Maria L. Ribeiro 《Fresenius' Journal of Analytical Chemistry》1998,360(2):252-255
A rapid and economical method is described for the determination of deltamethrin in wheat, rice, peanuts and corn. It is
based on simultaneous extraction and clean-up on a column packed with alumina and silica gel using n-hexane-ethyl ether (8:2,
v/v), followed by a derivatization step and gas-chromatographic analysis. Recoveries from fortified cereal and peanut samples
were determined at four concentration levels and ranged from 73 to 109%. The detection limits were 0.01 to 0.03 mg/ kg. This
method simplifies the traditional procedures in terms of sample size, solvent consumption and analysis time.
Received: 25 March 1997 / Revised: 3 June 1997 / Accepted: 4 June 1997 相似文献