Search results for "Gel permeation chromatography"
showing 10 items of 115 documents
Size Exclusion Chromatography for Semipreparative Scale Separation of Au 38 (SR) 24 and Au 40 (SR) 24 and Larger Clusters
2011
Size exclusion chromatography (SEC) on a semipreparative scale (10 mg and more) was used to size-select ultrasmall gold nanoclusters (2 nm) from polydisperse mixtures. In particular, the ubiquitous byproducts of the etching process toward Au(38)(SR)(24) (SR, thiolate) clusters were separated and gained in high monodispersity (based on mass spectrometry). The isolated fractions were characterized by UV-vis spectroscopy, MALDI mass spectrometry, HPLC, and electron microscopy. Most notably, the separation of Au(38)(SR)(24) and Au(40)(SR)(24) clusters is demonstrated.
Accurate determination of element species by on-line coupling of chromatographic systems with ICP-MS using isotope dilution technique
1998
Abstract The instrumental design for coupling different liquid chromatographic systems such as ion, reversed phase, and size exclusion chromatography as well as capillary gas chromatography, with ICP-MS for the determination of element species is described. For accurate analyses obtaining ‘real time’ concentrations of chromatographic peaks, the isotope dilution mass spectrometric (IDMS) technique is applied. Two different spiking modes are possible, one using species-specific and another one using species-unspecific spike solutions of isotope-enriched labelled compounds. The species-specific mode is only possible for element species well defined in their structure and composition, for examp…
Estimation of the Compatibility Between Poly(Methylmethacrylate) and Poly(Styrene Co Vinyl Phenol) Blends from Dilute Solution Measurements
2006
Abstract The compatibility of poly(methyl methacrylate) (PMMA) with poly(styrene‐co‐vinyl phenol) (PS‐VPh) with two different contents of vinyl phenol, 5.8 and 7.2%, in dilute tetrahydrofuran solutions has been investigated by size exclusion chromatography and fluorescence spectroscopy at 25°C. The chromatographic technique permits the evaluation of the preferential solvation at different PMMA/PS‐VPh ratios. Changes in the fluorescence properties of PS‐VPh, caused by its association with PMMA, were used to obtain the fraction of copolymer bound to PMMA at diverse PMMA compositions. Both techniques agree quantitatively in every system, indicating that the association increases when the PMMA …
Sulphonic acid strong cation-exchange restricted access columns in sample cleanup for profiling of endogeneous peptides in multidimensional liquid ch…
2006
Abstract In this work, the pore structural parameters and size exclusion properties of LiChrospher strong cation-exchange and reverse phase restricted access materials (RAM) are analysed. The molecular weight size exclusion limit for polystyrenes was found to be about 17.7 kDa, while for standard proteins, the molecular weight size exclusion limit was higher, at approximately 25 kDa. The average pore diameter on a volume basis calculated from the pore network model changes from 8.5 nm (native LiChrospher) to 8.6 nm (diol derivative) to 8.2 nm (sulphonic acid derivative) to 6.9 nm ( n -octadecyl derivative). Additional characterisations were performed on restricted access materials with nitr…
Preferential solvation of a dicyanate ester monomer and poly(sulfone) in different organic solvents by size-exclusion chromatography.
2002
Preferential solvation parameters A in the ternary systems solvent (1) -monomer (2) -polymer (3) were determined as a tool to measure the compatibility between the cyanate ester monomer Arocy B10 and poly(sulfone), PSF, in the presence of three organic solvents: tetrahydrofuran, dimethylformamide and dicloromethane. The A parameter was measured by size-exclusion chromatography at different monomer-to-polymer ratios. The quantitative evaluation was rigorously made at polymer-diluted conditions. PSF was found to be preferentially solvated by the monomer. Concerning the solvent used, systems containing tetrahydrofuran showed the strongest solvation, the lowest A values being those obtained in …
Enrichment of proteinaceous materials on a strong cation-exchange diol silica restricted access material: protein–protein displacement and interactio…
2004
A study of size exclusion and enrichment of proteins employing strong cation-exchange diol silica restricted access material (SCX-RAM) under saturation conditions is presented. Experiments were carried out with bacitracin, protamine, ribonuclease, lysozyme and bovine serum albumin as individual proteinaceous analytes as well as comprehensive binary mixtures and with human urine samples. Protein size dependent capacity features of the SCX-RAM column was observed. Bacitracin demonstrated the highest capacity followed by protamine while adsorption capacities of both ribonuclease and lysozyme were found smaller by a factor of 10. Applying binary protein samples occurring displacement effects we…
Preferential solvation of lysozyme and bovine serum albumin in copper salt solutions. A quantitative chromatographic study
1986
Preferential solvation λ parameters for systems containing water-copper salt-protein (lysozyme or bovine serum albumin) have been determined by gel permeation chromatography. When water is preferentially adsorbed by the protein, good agreement is found between λ values determined by this method and by equilibrium dialysis-differential refractometry. The influence of the concentration and type of anion component of the copper salt, protein concentration and temperature has been investigated. The methodology used also allows direct visualization of the metal ion bound to the protein and to determine binding parameters. Apparent association constants of 2.0 × 102 M−1 and 1.7 × 102 M−1 have bee…
Adsorption of proteins on porous and non-porous poly(ethyleneimine) and tentacle-type anion exchangers
1990
Abstract Adsorption isotherms of proteins [bovine serum albumin (BSA), soybean trypsin inhibitor and alcohol dehydrogenase] on anion exchangers were measured by on-line and off-line methods. The poly(ethyleneimine) (PEI) type and the tentacle-type materials exhibited principally different modes of adsorption. On thin layers of PEI, bonded to non-porous silica, BSA adsorption data corresponded to a monolayer of molecules, with 80% adsorbed side-on, with a high affinity constant for binding, and 20% adsorbed more weakly. With porous material, the amount of BSA bound per unit surface with high affinity was smaller. With tentacle-type anion exchangers, adsorption exceeded a monolayer by far, an…
Comparison of Different Processing Methods to Prepare Poly(lactid acid)–Hydrotalcite Composites
2013
The effect of the compounding method on the morphology and on the properties of poly(lactic acid) (PLA)-hydrotalcite (HT) composites was studied. Moreover, the influence of two different kinds of HT - organically modified (OM-HT) and unmodified (U-HT) - and their concentration was evaluated. The composites were prepared using either a single screw extruder (SSE), a counter rotating twin-screw compounder (TSC) or a corotating twin-screw extruder (TSE). The prepared materials were characterized by scanning electron microscopy, gel permeation chromatography (GPC) analysis, mechanical and rheological measurements. The results indicated that the best morphology, i.e., particles dimension and dis…
Suzuki polycondensation with a hairpin monomer.
2009
Two straight monomers were subjected to an AA/BB-type Suzuki polycondensation with a hairpin-shaped 1,8-anthrylene monomer as the counterpart leading to a novel polyarylene which should have the preferred conformation of a folded chain. The molar masses were determined by gel permeation chromatography and dynamic light scattering and found to be M(w) = 14,000 and M(n) = 7,000. MALDI-TOF MS analysis of a fraction provides a fingerprint of the step-growth nature of this polymerization.