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Characterization of suspension poly(vinyl chloride) resins and narrow polystyrene standards by size exclusion chromatography with multiple detectors: Online right angle laser-light scattering and differential viscometric detectors

Coelho, Jorge F. J.; Gonçalves, Pedro M. F. O.; Miranda, Dionísio; Gil, M. H.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
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805.80766%
This work reports the utilization of a multi-detector size chromatography for the characterization of poly(vinyl chloride) (PVC) resins prepared by suspension polymerization in the range of temperatures between 21 and 75 °C. The chromatography equipment offers the possibility of analyzing the samples in terms of their absolute molecular mass using a combination of three detectors (TriSEC): right angle light scattering (RALLS), a differential viscometer (DV) and refractive index (RI). The PVC resins were fully characterized concerning the molecular weight distribution (MWD), its dependence with intrinsic viscosity ([eta]) and molecular sizes (radius of gyration, Rg and hydrodynamic radius, Rh). Additionally, it is also presented the characterization of polystyrene narrow standards serving as reference polymers.; http://www.sciencedirect.com/science/article/B6TWW-4HHGNVH-4/1/170871b80274a89470f2a790d3ed999f

Monodisperse lignin fractions as standards in size-exclusion analysis Comparison with polystyrene standards

BOTARO, Vagner Roberto; CURVELO, Antonio Aprigio da Silva
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
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708.258%
The difficulty of preparing monodisperse lignin fractions on a large scale is a limiting factor in many applications. The present paper addresses this problem by examining the properties and size-exclusion behavior of lignin isolated by the acetosolv pulping process from post-extraction crushed sugarcane bagasse. The isolated lignin was subjected to a solvent pretreatment, followed by preparative gel permeation chromatography fractionation. The fractions were analyzed by high-performance size-exclusion chromatography (HPSEC) and these samples showed a great decrease in polydispersity, compared to the original acetosolv lignin. Several fractions of very low polydispersity, close to unity, were employed as calibration curve standards in HPSEC analysis. This original analytical approach allowed calibration with these lignin fractions to be compared with the polystyrene standards that are universally employed for lignin molecular mass determination. This led to a noteworthy result, namely that the lignin fractions and polystyrene standards showed very similar behavior over a large range of molecular masses in a typical HPSEC analysis of acetosolv lignin. (C) 2009 Elsevier B.V. All rights reserved.

Rapid, quantitative determination of polar compounds in fats and oils by solid-phase extraction and size-exclusion chromatography using monostearin as internal standard

Márquez-Ruiz, G.; Jorge, N.; Martín-Polvillo, M.; Dobarganes, M. C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 55-60
ENG
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A rapid and simple method was developed for quantitation of polar compounds in fats and oils using monostearin as internal standard. Starting from 50 mg of oil sample, polar compounds were obtained by solid-phase extraction (silica cartridges) and subsequently separated by high-performance size-exclusion chromatography into triglyceride polymers, triglyceride dimers, oxidized triglyceride monomers, diglycerides, internal standard and fatty acids. Quantitation of total polar compounds was achieved through the internal standard method and then amounts of each group of compounds could be calculated. A pool of polar compounds was used to check linearity, precision and accuracy of the method, as well as the solid-phase extraction recovery. The procedure was applied to samples with different content of polar compounds and good quantitative results were obtained, especially for samples of low alteration level.

Further characterization of the subunits of the giant extracellular hemoglobin of Glossoscolex paulistus (HbGp) by SDS-PAGE electrophoresis and MALDI-TOF-MS

Carvalho, Francisco Adriano O.; Carvalho, José Wilson P.; Santiago, Patrícia S.; Tabak, Marcel
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 2144-2151
ENG
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711.1891%
Further characterization of hemoglobin of Glossoscolex paulistus (HbGp) subunits was performed based on SDS-PAGE, size exclusion chromatography (SEC) and MALDI-TOF-MS analysis. SDS-PAGE has shown a total of four linker chains, two quite intense and two of lower intensity. HbGp fractions (I-VI), obtained by size exclusion chromatography (SEC), from oligomeric dissociation at alkaline pH 9.6, were monitored. Fraction I is identical to the whole protein. The monomeric chains c, obtained from the trimer abc reduction, present four isoforms with MM 17,336 Da, 17,414 Da, 17,546 Da and 17,620 Da. Furthermore, the trimer subunit presents two isoforms, T 1 and T 2, with MM 51,200 ± 60 and 51,985 ± 50 Da, respectively. Based on SDS-PAGE, the linker chains seem to be distributed along the different fractions of the SEC chromatogram, appearing along the peaks corresponding to fractions I-V. The fraction IV contains, predominantly, trimers with some linkers contamination. The strong interaction of linker chains L with the trimers abc, makes it difficult to obtain these subunits in pure form. The monomer d in fraction VI appears to be quite pure, in agreement with previous studies. © 2011 Elsevier Ltd. All rights reserved.

Estudo dos modos batelada e reciclo externo estacionário para a separação do ácido hialurônico por cromatografia de exclusão por tamanho; Study of batch and steady state recycling modes for hyaluronic acid separation by size exclusion chromatography

Anayla dos Santos Sousa
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 23/09/2011 PT
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824.7451%
O Ácido hialurônico (AH) é um polissacarídeo linear com importantes aplicações na indústria farmacêutica, médica e cosmética, fazendo-se necessária sua purificação por ser oriundo de uma variedade de fontes, animal e não animal. Assim sendo, o presente trabalho discorre sobre a separação do AH produzido por fermentação em meio de cultura sintético, utilizando a técnica cromatográfica de exclusão por tamanho. Determinaram-se as melhores condições de separação utilizando, inicialmente, uma coluna de exclusão por tamanho operando em batelada. Estas condições foram mantidas em todos os ensaios e serviram de modelo para a obtenção dos parâmetros para o escalonamento do processo. Ainda em batelada, avaliou-se a inserção da técnica cromatográfica de troca iônica acoplada à exclusão por tamanho, com o intuito de aprimorar a separação do AH, averiguando resinas de caráter catiônico e aniônico. Realizou-se um estudo comparativo entre o processo em batelada, com e sem a inserção da troca iônica, e o semicontínuo operado com reciclo externo estacionário (REE), visando a obtenção de frações de AH e proteínas com elevado grau de pureza. Considerando-se o processo semicontínuo operado em REE foram avaliados diferentes volumes de reciclo...

Characterization of clarified medium from submerse and semisolid cultivation of OF Aspergillus awamori NRRL3112 by size-exclusion chromatography

MINAMI,N.M.; LUCARINI,A.C.; KILIKIAN,B.V.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/1999 EN
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In this study, a preparative size-exclusion chromatography of two different clarified media obtained from submerse and semisolid culture of the mold Aspergillus awamori was carried out. Characterization and comparison of the quantities of glucoamylase and contaminant proteins present in these media were possible. Glucoamylase is the protein with the higher molecular weight in both media analyzed, varying from 72 to 80kDa in the submerse culture and from 68 to 90kDa in the semisolid culture. Also, glucoamylase protein concentration is higher in the submerse culture than in the semisolid culture. The other proteins in the submerse culture presented molecular weights lower than 12kDa and in the semisolid culture their molecular weights varied from 21 to 37kDa and below 10kDa.

HEMA/MMA/EDMA packing material evaluation for size exclusion chromatography (SEC)

Vianna-Soares,Cristina Duarte; Cherng-Ju,Kim; Borenstein,Michael Robert
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2005 EN
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906.9921%
HEMA/MMA/EDMA (2-hydroxyethyl methacrylate/methyl methacrylate/ethyleneglycol methacrylate) copolymer beads have been synthesized for use in aqueous SEC. This porous chromatographic support consisted of a large average particle size (250 µm) and contained macropores with a median pore size of approximately 880 Å. The material was packed in glass and stainless columns to assess their chromatographic performance. The packed columns were calibrated using narrow molecular weight (MW) distribution standards (dextran) and exhibited a range of molecular weight separation between 40,000 and 2,000,000 daltons. The packing material showed the ability to separate large molecules through the size exclusion mechanism.

Size exclusion chromatography does not require pores

Brooks, Donald E.; Haynes, Charles A.; Hritcu, Doina; Steels, Bradley M.; Müller, Werner
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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708.8915%
Separation of macromolecules on the basis of their molecular weight by size exclusion chromatography has long been considered to be caused by the geometry-dependent partition of macromolecules between a continuous phase and the porous interior of a gel or cross-linked bead. The volume of a pore accessible to a solute is limited by its relative dimensions, so larger molecules will have access to a smaller volume and will remain in a bead for a shorter time than smaller solutes. Our recent alternate picture proposes that the partition coefficient can be calculated from a thermodynamic model for the free energy of mixing of the solute with the gel phase. Size-dependent exclusion caused by the unfavorable entropy of mixing associated with the partition is predicted; the magnitude of the effect is modified by enthalpic interactions between the solute and the gel phase. This concept is extended here to describe the partition of macromolecules into a layer of terminally attached polymer chains grafted onto a solid bead. Both simple mean field and self-consistent field theory calculations predict size-dependent entropic exclusion. Experimental results obtained with neutral polymer chains grafted onto solid polystyrene latex beads confirm the predictions.

Measurements of Protein-Protein Interactions by Size Exclusion Chromatography

Bloustine, J.; Berejnov, V.; Fraden, S.
Fonte: Biophysical Society Publicador: Biophysical Society
Tipo: Artigo de Revista Científica
Publicado em /10/2003 EN
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708.258%
A method is presented for determining second virial coefficients (B2) of protein solutions from retention time measurements in size exclusion chromatography. We determine B2 by analyzing the concentration dependence of the chromatographic partition coefficient. We show the ability of this method to track the evolution of B2 from positive to negative values in lysozyme and bovine serum albumin solutions. Our size exclusion chromatography results agree quantitatively with data obtained by light scattering.

Analysis of protein-protein interaction by simulation of small-zone size exclusion chromatography. Stochastic formulation of kinetic rate contributions to observed high-performance liquid chromatography elution characteristics.

Stevens, F J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1989 EN
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705.8394%
High-performance liquid chromatography (HPLC) procedures provide size-exclusion chromatography with sufficient speed that the elution characteristics of mixtures of interacting macromolecules are potentially determined by the kinetics of association and dissociation. However, few studies have yet addressed the consequences of interaction kinetics on HPLC analyses or evaluated the potential application of HPLC methods for the qualitative and quantitative interpretation of macromolecular interaction kinetics. An earlier simulation of small-zone chromatography of interacting molecules (Stevens, F. J. 1986. Biochemistry. 25:981-993) has been modified to incorporate the effects of association/dissociation kinetics on elution behavior. The previous assumption of instantaneous equilibration has been replaced by explicit calculation of partial relaxation of complexed and free constituent mixtures during each iteration of the simulation. In addition, a stochastically based formulation has been introduced to determine a velocity probability distribution that emulates the partial intermixing of free and complexed pools during the iteration cycle. The simulation generates bimodal elution profiles representing stable complexed and free components of mixtures for which interaction is characterized by slow kinetics relative to chromatography run times. For mixtures with rapid kinetics...

Megadalton Complexes in the Chloroplast Stroma of Arabidopsis thaliana Characterized by Size Exclusion Chromatography, Mass Spectrometry, and Hierarchical Clustering*

Olinares, Paul Dominic B.; Ponnala, Lalit; van Wijk, Klaas J.
Fonte: The American Society for Biochemistry and Molecular Biology Publicador: The American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
EN
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711.75516%
To characterize MDa-sized macromolecular chloroplast stroma protein assemblies and to extend coverage of the chloroplast stroma proteome, we fractionated soluble chloroplast stroma in the non-denatured state by size exclusion chromatography with a size separation range up to ∼5 MDa. To maximize protein complex stability and resolution of megadalton complexes, ionic strength and composition were optimized. Subsequent high accuracy tandem mass spectrometry analysis (LTQ-Orbitrap) identified 1081 proteins across the complete native mass range. Protein complexes and assembly states above 0.8 MDa were resolved using hierarchical clustering, and protein heat maps were generated from normalized protein spectral counts for each of the size exclusion chromatography fractions; this complemented previous analysis of stromal complexes up to 0.8 MDa (Peltier, J. B., Cai, Y., Sun, Q., Zabrouskov, V., Giacomelli, L., Rudella, A., Ytterberg, A. J., Rutschow, H., and van Wijk, K. J. (2006) The oligomeric stromal proteome of Arabidopsis thaliana chloroplasts. Mol. Cell. Proteomics 5, 114–133). This combined experimental and bioinformatics analyses resolved chloroplast ribosomes in different assembly and functional states (e.g. 30, 50, and 70 S)...

Molecular Mass Characterization of Glycosaminoglycans with Different Degrees of Sulfation in Bioengineered Heparin Process by Size Exclusion Chromatography

Wang, Zhenyu; Zhang, Fuming; Dordick, Jonathan S.; Linhardt, Robert J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/10/2012 EN
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716.58555%
Different degrees of glycosaminoglycan sulfation result in their different charge densities. The charge density differences impact their migration behavior in polyacrylamide gel electrophoresis and size exclusion chromatography, two of the most common methods for determining relative molecular masses of polysaccharides. In this study, we investigated the feasibility of using commercially available heparin oligosaccharides as calibrants for measuring the relative molecular masses of intermediates in a bioengineered heparin process that have different levels of sulfation. A size exclusion chromatography method was established that eliminates this charge density effect and allows the determination of relative molecular mass using a single calibration curve with heparin oligosaccharides calibrants. This is accomplished by overcoming the electrostatic interaction between the glycosaminoglycans and size exclusion chromatography stationary phase using high ionic strength mobile phase.

Ultra-High Pressure Fast Size Exclusion Chromatography for Top-Down Proteomics

Chen, Xin; Ge, Ying
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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704.9614%
Top-down mass spectrometry (MS)-based proteomics has gained a solid growth over the past few years but still faces significant challenges in the liquid chromatographic separation of intact proteins. In top-down proteomics, it is essential to separate the high mass proteins from the low mass species due to the exponential decay in S/N as a function of increasing molecular mass. Size exclusion chromatography (SEC) is a favored liquid chromatography method for size-based separation of proteins but suffers from notoriously low resolution and detrimental dilution. Herein we reported the use of ultra-high pressure (UHP) SEC for rapid and high-resolution separation of intact proteins for top-down proteomics. Fast separation of intact proteins (6 – 669 kDa) was achieved in less than 7 min with high-resolution and high efficiency. More importantly, we have shown that this UHP-SEC provides high-resolution separation of intact proteins using a MS-friendly volatile solvent system, allowing the direct top-down MS analysis of SEC eluted proteins without an additional desalting step. Taken together, we have demonstrated that UHP-SEC is an attractive LC strategy for the size-separation of proteins with great potential for top-down proteomics.

Fluorescence Characteristics of Size-Fractionated Dissolved Organic Matter: Implications for a Molecular Assembly Based Structure?

Romero-Castillo, Cristina; Chen, Meilian; Yamashita, Youhei; Jaffe´, Rudolf
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
803.4019%
Surface freshwater samples from Everglades National Park, Florida, were used to investigate the size distributions of natural dissolved organic matter (DOM) and associated fluorescence characteristics along the molecular weight continuum. Samples were fractionated using size exclusion chromatography (SEC) and characterized by spectroscopic means, in particular Excitation-Emission Matrix fluorescence modeled with parallel factor analysis (EEM-PARAFAC). Most of the eight components obtained from PARAFAC modeling were broadly distributed across the DOM molecular weight range, and the optical properties of the eight size fractions for all samples studied were quite consistent among each other. Humic-like components presented a similar distribution in all the samples, with enrichment in the middle molecular weight range. Some variability in the relative distribution of the different humic-like components was observed among the different size fractions and among samples. The protein like fluorescence, although also generally present in all fractions, was more variable but generally enriched in the highest and lowest molecular weight fractions. These observations are in agreement with the hypothesis of a supramolecular structure for DOM, and suggest that DOM fluorescence characteristics may be controlled by molecular assemblies with similar optical properties...

Molecular characterization of recombinant Hepatitis B surface antigen from Chinese hamster ovary and Hansenula polymorpha cells by high-performance size exclusion chromatography and multi-angle laser light scattering

Zhou, W.; Bi, J.; Janson, J.; Li, Y.; Huang, Y.; Zhang, Y.; Su, Z.
Fonte: Elsevier Science BV Publicador: Elsevier Science BV
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
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801.6107%
The molecular weight and size of recombinant Hepatitis B surface antigen (HBsAg) derived from Chinese hamster ovary (CHO) and the Hansenula polymorph have been characterized by high-performance size exclusion chromatography with multi-angle laser light scattering (HPSEC-MALLS). The average molecular weight of CHO-derived HBsAg particle (CHO-rHBsAg) (4921 kDa) was higher than that of H. polymorpha yeast strain (Hans-rHBsAg) (3010 kDa). The size of CHO-rHBsAg (22.1 nm) is nearly the same as that of native HBsAg compared to 18.1 nm for Hans-rHBsAg. The average monomer numbers were found to be 155 for CHO-rHBsAg and 86 for Hans-rHBsAg, respectively. The data obtained support the assumption that the higher immunogenicity of CHO-derived HBsAg is related to its more favorable macromolecular assembly structure.; http://www.elsevier.com/wps/find/journaldescription.cws_home/643040/description#description; Weibin Zhou, Jingxiu Bi, Jan-Christer Janson, Yan Li, Yongdong Huanga, Yan Zhang and Zhiguo Su

A gel-based method for purification of apolipoprotein A-I from small volumes of plasma

Suetani, R.; Sorrenson, B.; Sviridov, D.; McCormick, S.
Fonte: Amer Soc Biochemistry Molecular Biology Inc Publicador: Amer Soc Biochemistry Molecular Biology Inc
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
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704.4054%
We present here a gel-based method for rapid purification of apolipoprotein A-I (apoA-I) from small volumes of human plasma. After isolation of high density lipoprotein from plasma, the apoA-I protein was separated by electrophoresis and the apoA-I band excised from the gel. The apoA-I was then eluted from the gel strip, concentrated, and delipidated ready for use. The structure and function of the gel-purified apoA-I protein was compared against apoA-I purified by the traditional size-exclusion chromatography method. The α-helical content of the gel-purified apoA-I as determined by circular dichroism was similar to chromatography-purified apoA-I. The functional activity of gel-purified apoA-I, as determined by cholesterol efflux assays in primary human fibroblasts and RAW264.7 macrophages, was also comparable with chromatography-purified apoA-I. This method is a valid alternative for apoA-I purification with some advantages over traditional chromatography purification including a much reduced plasma volume requirement, less time and cost, and a higher percentage protein recovery. The method is particularly suitable for applications requiring the purification of apoA-I from multiple human or animal samples of interest.; Rachel J. Brace...

Toward a full characterization of native starch: separation and detection by size-exclusion chromatography

Hoang, N.L.; Landolfi, A.; Kravchuk, A.; Girard, E.; Peate, J.; Hernandez, J.; Gaborieau, M.; Kravchuk, O.; Gilbert, R.; Guillaneuf, Y.; Castignolles, P.
Fonte: Elsevier Science BV Publicador: Elsevier Science BV
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
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1011.1891%
The structure of starch molecules is relevant to nutrition and industrial applications. Size-exclusion chromatography (SEC, also known as GPC) of native starch generally suffers non-satisfactory repeatability and reproducibility of the dissolution and separation. This work combines two polar organic solvents: dimethylsulfoxide for complete dissolution and dimethylacetamide to limit shear degradation. The separation is as repeatable as that of polystyrene standards performing dissolution and separation at 80 degrees C. Successful covalent-labeling on the glucose unit is claimed to be published here for the first time in non-degradative conditions and allows the use of UV detector with significantly higher sensitivity than with a refractometer.; http://www.journals.elsevier.com/journal-of-chromatography-a/; Ngoc-Ly Hoang, Antonin Landolfi, Anastasiya Kravchuk, Etienne Girard, Jonathan Peate, Javier M. Hernandez, Marianne Gaborieau, Olena Kravchuk, Robert G. Gilbert, Yohann Guillaneuf and Patrice Castignolles

Towards well-defined nanocrystal assemblies: Using size exclusion chromatography to understand soluble nanocrystal complexes

Krueger, Karl Marvin
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
713.5463%
This thesis develops and applies size exclusion chromatography (SEC) for the accurate characterization and size separation of semiconductor and metallic nanoparticles. Size exclusion chromatography is employed for the first time to determine the size and size distribution of cadmium selenide nanocrystals. The method accurately determines nanocrystal size as well as the length of any surface capping ligands. The separation resolution is enhanced using recycling SEC and a shape separation of quantum dots and multipods is performed. SEC is further applied to measure the hydrodynamic diameter of gold and cadmium selenide nanocrystals passivated with polystyrene. Polystyrene occupies a brush conformation on the surface of these nanoparticles and the polymer length is found to scale linearly with molecular weight and as the cube root of polymer coverage. Using these measurements, a general formula is proposed to predict the hydrodynamic diameter of polymer coated nanoparticles. Gold and cadmium selenide nanocrystals discretely functionalized with different numbers of polystyrene molecules are also separated. Fluorescence and 1H-NMR measurements of collected fractions confirm the separation and the population of the species is studied as a function of polystyrene concentration. These discrete nanocrystal-polymer conjugates form ordered microphases upon drying that are dependent upon the tether number. Such data illustrates the potential of these species as building blocks for self-assembly.

Free Radical Polymerization studies of vinyl ester monomers using Pulsed-Lased Polymerization with Size Exclusion Chromatography (PLP-SEC)

Monyatsi, Otlaatla
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
1008.258%
Polyvinyl acetate and other polyvinyl esters, and their copolymers are used in coatings, adhesives and plastics, and hence fundamental understanding of the mechanisms and polymerization kinetics is vital for process development, and production of existing and new polymer grades in an effective and safe manner. The propagation kinetics of radical homopolymerization (bulk) of vinyl acetate (VAc), vinyl pivalate (VPi) and vinyl benzoate (VBz) was studied using Pulsed-Laser Polymerization coupled with Size Exclusion Chromatography (PLP-SEC) at laser pulse repetition rate (prr) between 2 and 500 Hz, and the temperature range of 25 - 90 °C. The propagation rate coefficient, kp, determined for VAc and VPi increases significantly with prr (20 % between 200 and 500 Hz prr), with the kp value for VPi ~50 % higher than that of VAc. This significant increase in kp with prr has been explained by the head-to-head addition defects that occur during vinyl ester polymerizations. For VBz, no kp value was reported due to lack of PLP-structure, likely due to resonance stabilization of the radical. Solution polymerization of VAc and VPi was also studied by PLP-SEC using ethyl acetate (EAc) and heptane (50 % by volume) at 50 °C, with the kp values having no substantial solvent effect. The polymerization kinetics of these vinyl ester monomers were also investigated using small-scale batch polymerization at 60 °C both in bulk and in solution (using EAc). The monomer conversion profiles obtained showed the same pattern in both bulk and solution...

A rapid method for determination of polar compounds in used frying fats and oils; Método rápido para la determinación de compuestos polares en aceites y grasas de fritura

Marmesat, Susana; Velasco, Joaquín; Márquez Ruiz, Gloria; Dobarganes, M. Carmen
Fonte: Consejo Superior de Investigaciones Científicas (España) Publicador: Consejo Superior de Investigaciones Científicas (España)
Tipo: Artículo
ENG
Relevância na Pesquisa
707.80125%
The determination of polar compounds by adsorption chromatography is the most accepted method for the analysis of used frying fats due to its high precision and accuracy. However, this method is expensive and time consuming. In this study, a rapid analytical method to determine polar compounds is proposed. Starting from milligrams of sample dissolved in a solution of hexane containing methyl oleate as internal standard, the nonpolar fraction, which comprises the non-altered triglycerides (TG) and the internal standard, is obtained by solid phase extraction. Then, the non polar fraction is quantitatively analyzed in 15 min by high-performance size-exclusion chromatography (HPSEC) and the polar fraction is determined by difference of weight. Response factors for pure TG and FAME were calculated. Six samples of sunflower oils of different degrees of unsaturation were analyzed in triplicate and the results were compared with those obtained by the gravimetric method based on silica classical column chromatography. Results showed no significant differences between the two methods. In addition, the repeatability of the proposed method was excellent, as the coefficient of variation ranged from 1.5 to 13% depending on the contents of polar compounds.; La determinación de compuestos polares mediante cromatografía de adsorción es el método más aceptado en el análisis de aceites y grasas de fritura debido a su elevada exactitud y precisión. Sin embargo...