Size exclusion chromatography removal

This reversed-phase chromatography method was successfully used in a production-scale system to purify recombinant insulin. The insulin purified by reversed-phase chromatography has a biological potency equal to that obtained from a conventional system employing ion-exchange and size-exclusion chromatographies (14). The reversed-phase separation was, however, followed by a size-exclusion step to remove the acetonitrile eluent from the final product (12,14). 

Remove excess reactants from the reaction mixture using size exclusion chromatography on a column of Sephadex G25 (or equivalent). 

Remove excess crosslinker and reaction by-products by dialysis or size exclusion chromatography. For small quantities of bait proteins, dialysis may be the better choice, because gel filtration columns often bind nonspecifically enough protein to make recoveries unacceptably low. 

Remove excess crosslinker and reaction by-products by dialysis or size exclusion chromatography. 

Tetramethylammonium chloride (2 mg) and 5 (1. Og) were placed in a vial, sealed, and heated in an oil bath at 107°C for 65 h. H-NMR analysis of the colorless, viscous grease showed the ratio of signals at 4.6 and 3.90ppm as ca. 60/1. The small amount of cyclic dimer formed (GC anlaysis) was removed by Kugelrohr distillation (up to 100°C/0.05 mm). 19F-NMR featured the internal/ terminal CF2CH20 group ratio as ca. 83/1. Size-exclusion chromatography showed the major peak with Mn, =26,700 and Mw =52,800, consistent with condensation polymer 7. 

ASE using dichloromethane has been applied to extract alkylphenols and short-chain NPEO from sediment [8,47]. Samples of 2-5 g were extracted in two cycles of 30 mL at 100°C and 69 atm. Clean-up was performed using size exclusion chromatography to remove high molecular weight lipids, and then using normal phase HPLC. 

Three gradients of 0.0-0.5 M sodium chloride were run consecutively at 4°C in 0.05 M sodium acetate-acetic acid, 1 mM sodium azide, pH 5.25, followed by 0.05 M sodium acetate-acetic acid, 1 mM sodium azide, pH 3.5, and finally by 0.05 M sodium dihydrogen phosphate-disodium hydrogen phosphate (approx. 1 3), 1 mM sodium azide, pH 7.0. After sample application, the column was washed with the starting buffer to remove any non-bound compounds. Elution was continued with the high salt buffer. Fractions of 4 ml were collected and assayed for reactivity towards ninhydrin and for electric conductivity (salt concentration) after 75-fold dilution of a 100-pl aliquot. Ninhydrin-positive fractions were pooled for each peak, concentrated, and desalted by size exclusion chromatography (see above). 

If the sample is of the purity required, only buffer exchange is needed to give the final product. If further purification is required, a size exclusion chromatography step (SEC) is usually carried out. This step both removes contaminants from the sample, tyqjicaUy giving protein products of >90% purity, and gives information regarding the... 

The chemical imidization of poly(amic alkyl esters) was only reported very recently [59], although reports in the literature claim chemical imidization with a traditional acetic anhydride/pyridine mixture [87]. The chemical imidization of poly(amic alkyl esters) is based on the observation that PMDA/ODA based poly(amic ethyl ester) samples, when formulated at low concentrations for size exclusion chromatography, precipitated upon standing overnight [88]. Distillation of the NMP from phosphorus pentoxide to remove low levels of methyl-amine, a known impurity in this particular solvent, eliminated this unusual behavior. The precipitated polymer had significant levels of imidization as evidenced by IR. Apparently, organic bases, such as alkyl amines, were able to catalyze the conversion of amic alkyl esters to the corresponding imide. 

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. 

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. 

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