Chromatography, size exclusion procedure

Solvent conversion of columns designed for aqueous size exclusion chromatography is rarely a problem. However, it should always be carried out at slow flow rates. For Ultrahydrogel columns, the recommended flow rate for a solvent conversion is below 0.3 ml/min. One should typically use 0.1 ml/min for most solvent conversion procedures. 

Saponified apple MHR was treated with RG-hydrolase, and the branched RG-hydrolase MHR oligomers were isolated using size-exclusion chromatography as described in Mutter et al. (1994). A similar procedure was carried out with RG-lyase, and the branched RG-lyase MHR oligomers were isolated as described in Mutter et al. (1996). 

A new direct method for using size exclusion chromatography (SEC) to evaluate polymer intrinsic viscosity [n] is discussed. Sample viscosity information is obtained by combining SEC elution curve data and calibration data using direct SEC-[n] calibration procedures without involving polymer molecular weight calculations. The practical utility, convenience and the expected precision of the proposed method are illustrated. 

A variety of procedures were utilized to analyze this reaction mixture and to characterize a,10-diaminopolystyrene. Thin layer chromatographic analysis using toluene as eluent exhibited three spots with Rf values of 0.85, 0.09, and 0.05 which corresponded to polystyrene, poly(styryl)amine and a,w-diaminopolystyrene (see Figure 1). Pure samples of each of these products were obtained by silica gel column Chromatography of the crude reaction mixture initially using toluene as eluent [for polystyrene and poly(styryl)amine] followed by a methanol/toluene mixture (5/100 v/v) for the diamine. Size-exclusion chromatography could not be used to characterize the diamine since no peak was observed for this material, apparently because of the complication of physical adsorption to the column packing material. Therefore, the dibenzoyl derivative (eq. 5) was prepared and used for most of the analytical characterizations. 

A reliable procedure for determination of molecular parameters number, weight and z-averages of the molecular weight (Mj, i = n, w and z respectively) for polyethylenes, PE, by means of Size Exclusion Chromatography, SEC, has been developed. The Waters Sci. Ltd. GPC/LC Model 150C was used at 135 C with trichlorobenzene, TCB, as a solvent. The standard samples as well as commercial stabilized and not stabilized PE-resins were evaluated. The effects of sampling, method of solution preparation, addition of antioxidant(s), thermal and shear degradation were studied. The adopted procedure allows reproducible determination of and M , with a random error of 4% and M2, with 9%, within 2 to 72 hrs from the initial moment of preparation of solutions. 

Figure 10.2 One of the procedures for entrapping an enzyme, E, (or any other solute) inside liposomes. The non-entrapped enzyme is eliminated by size exclusion chromatography, then the substrate (ADP in this case) is left to permeate throughout, the ADP excess is again eliminated chromatographically, and the reaction kinetics - due to the internalized enzyme reaction - measured. (From Walde et al., 1994b.)...

Ultrafiltration and Size-Exclusion Chromatography. The apparent molecular weight distribution of each sample was determined by sequential use of ultrafiltration (UF) and size-exclusion chromatography (SEC). A modification of a procedure proposed by Chian and DeWalle (11) was used. Approximately 10 mg of a sample was dissolved in 200... 

Bean et al. (10) used size-exclusion chromatography to remove materials of MW >800. This method of cleanup was rejected because size-exclusion chromatography might introduce new artifacts and cause additional delays in sample analysis time. Because the matrix problem appeared to have acidic components, it was decided that a base extraction procedure might remove these materials. 

It is essential that the procedure described in Section 3.1.2. be performed approx 24 h before the procedure described in Section 3.1 3, because the deprotected thiolated avidin and the maleimide derivative of the protein are unstable. Purification of the maleimide-derivatized protein by size exclusion chromatography can be performed more rapidly than dialysis, however, the former leads to dilution of the protein and a decrease in the yield of the conjugate. 

The authors have applied this same procedure to peach purees, although at the pH of the peach product (—3.9). In that case, however, the PGase activity associated with the peach puree was relatively soluble in water. Hence, the initial water extracts had significant PGase activity. Therefore, one may choose to assay the water extract itself. As noted in the protocol for removal of salt, the soluble reducing sugars in the water extract can be removed by techniques such as dialysis or size-exclusion chromatography. 

Using the normal addition procedure (02 diffusion into a 75/25 benzene/THF solution of poly(styryl)lithium) the 37% dimer fraction analyzed for 19% alkyl radical dimer and 18% macroperoxide after LiAlH4 reduction. The yield of macroperoxide was also confirmed by thermal decomposition experiments in refluxing toluene, followed again by size exclusion chromatography analysis of the dimer fraction. The amount of hydroperoxide could be deduced from the difference between the amounts of total peroxide (determined by iodometric titration) versus the amount of macroperoxide determined by LiAlH4 reduction. 

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