Search results for " Extraction"
showing 10 items of 1344 documents
Supercritical-fluid extraction of chlorofluoroalkanes from rigid polyurethane foams
1996
Abstract Preliminary results about a process for recovering expanding agents chlorofluoroalkanes (CFCs) both trapped in the cavities and dissolved in the polymer from rigid polyurethane foams are reported. The performances of liquid and supercritical carbon dioxide, and of CO2-propane supercritical mixtures were compared. Better results in terms of extraction time and amount of extracted CFCs were obtained with finely ground materials and supercritical propane-carbon dioxide fluids.
Experimental design approach in the synthesis of molecularly imprinted polymers specific for iprodione fungicide
2015
International audience; An experimental design (ED) approach was applied to study the weight of three factors in the synthesis of a molecularly imprinted polymer (MIP) specific for iprodione fungicide. The objective was to obtain a high specific polymer with the best performance of iprodione binding. Thirteen iprodione-imprinted polymers and 13 non-imprinted polymers (NIP) were synthesized according to ED having 3 influencing factors: the polymerization method, the crosslinker nature and the functional monomer type. For each factor, two levels were studied: bulk and precipitation polymerization for the first factor, trimethylolpropane trimethacrylate (TRIM) and ethylene glycol dimethacrylat…
Electrophoretic pattern of the polypeptide component in the tight DNA-protein complexes in rat and chicken tissues and its partial characterisation i…
2010
Electrophoretic pattern of the polypeptide component in the tight DNA-protein complexes in rat and chicken tissues and its partial characterisation in rat liverTightly bound to DNA proteins (TBP) are a protein group that remain attached to DNA with covalent or non-covalent bonds after its deproteinisation. The distribution of TBP in genes reflects the type of cell differentiation. It has been hypothesised that TBP binding is involved in regulation of gene expression. Early studies reported uniformity of the TBPs from different sources. Later it was shown that TBPs obtained from DNA, isolated in mild conditions from evolutionary distant species, are different. Application of chloroform DNA e…
Anionic tert-butyl-calix[4]arenes substituted at the narrow and wide rim by cobalt bis(dicarbollide)(1−) ions and CMPO-groups. Effect of stereochemis…
2013
Abstract Two ionic calix[4]arenes substituted at the narrow rim with an unpaired number ( n ) of cobalt bis(dicarbollide)(1−) anions ( 1 − ) ( n = 1 and 3) and (4 − n ) CMPO groups ( 3c , 4c ) have been synthesized via a three-step procedure based on nitrile substituted calix[4]arene precursors. Conjointly with them, the compound with a paired ratio of the groups, where n = 2 and the same substituents are located in mutually adjacent 1,2-positions, is reported ( 5c ). Another compound with the paired ratio, but from a wide rim series ( 6c ) ( n = 2) was successfully prepared starting from calix[4]arenes substituted with two nitro functions and two –OH sites available for further modific…
Green extraction approach for the recovery of polyphenols from Croatian olive leaves (Olea europea)
2017
Abstract Pressurized liquid extraction (PLE) is shown as an innovative green technology for the effective extraction of the various phytochemicals from food by-products, therefore the aims of this study were to evaluate the application of PLE to engineer green extracts of Croatian olive leaves ( Olea europaea , cv. Oblica) for potential industrial production (functional foods/pharmaceuticals). PLE was conducted under various cycle numbers (1, 2), temperature (60, 80, 100 °C) and static times (5, 10, 15 min). Obtained extracts were characterized in terms of: (i) total polyphenols (TP); (ii) total flavonoids (TF); hydroxycinnamic acids (HCA); and (iv) flavonols (FLA). Response surface methodo…
Chemical speciation of polycyclic aromatic hydrocarbons in sediments: partitioning and extraction of humic substances.
2010
The primary objective of this study was to examine the chemical speciation of polycyclic aromatic hydrocarbons (PAHs) found in sediments endowed with different characteristics. To achieve this purpose and because the nature of the sediments influences the distribution of PAHs, we have analyzed four different types of sediments. To study the role of organic matter in the sequestration of PAHs, we fractionated humic substances into humic acids and humin–mineral fractions. After their separation and purification, the humic components were examined for their sorptive reactivity by extracting them with organic solvents; these extracts were subsequently subjected to GC/MS analysis. Our results sh…
Pressure-Induced Formation of Diblock Copolymer "Micelles" in Supercritical Fluids. A Combined Study by Small Angle Scattering Experiments and Mean-F…
2004
We developed a simple mean-field theory to describe polymer and AB diblock copolymer phase separation in supercritical (SC) fluids. The highly compressible SC fluid has been described by using a phenomenological hole theory, properly extended to consider the solvent/polymer/vacancy pseudoternary mixture. The model has been applied to describe the phase behavior of AB-diblock copolymers under the assumption of a strong solvent selectivity for just one copolymer chain. In our model the solvent selectivity is a strong function of the external pressure because in compressible fluids vacancies reduce the number of favorable solvent-polymer contacts. The combined effect of the pressure on the ave…
Polymer- and template-related factors influencing the efficiency in molecularly imprinted solid-phase extractions
1999
Abstract This review identifies the factors of importance in the development of molecularly imprinted polymers for use in solid-phase extractions and summarizes the results obtained to date in the area of bioanalysis, pharmaceutical analysis and environmental analysis.
Study of silica-structured materials as sorbents for organophosphorus pesticides determination in environmental water samples
2018
Abstract A novel sorbent based on a UVM-7 mesoporous silica doped with Ti has been synthesized and used for solid-phase extraction of several organophosphorus pesticides in environmental water samples followed by gas chromatography coupled to a nitrogen-phosphorus selective detector. Thus, mesoporous silica materials doped with Ti and Fe as well as immobilized cyclodextrin silica-based supports were prepared and morphologically characterized by several techniques such as transmission electronic microscopy, nitrogen adsorption-desorption and X-ray diffraction. These sorbents were comparatively evaluated, and Ti25-UVM-7 material was selected as the best solid phase. After optimization of extr…
Determination of soyasaponins I and βg in raw and cooked legumes by solid phase extraction (SPE) coupled to liquid chromatography (LC)-mass spectrome…
2013
Legumes contain a rich variety of phytochemicals as soyasaponins, triterpenoidal glycosides that possess multiple health-promoting properties, such as lowering of cholesterol. In this work, the quantification of soyasaponins I and βg in 60 raw and cooked legumes by using a solid phase extraction (SPE) coupled to a liquid chromatography (LC)-mass spectrometry (MS) method was carried out. Results showed that lentils are a good source of soyasaponins, with a content of soyasaponin I that ranged from 636 to 735 mg kg(-1) and of soyasaponin βg from 672 to 1807 mg kg(-1). The cooking process produced a small loss of soyasaponins in water, that is, 4.8-8.7%, and partially converted soyasaponin βg …