Size exclusion chromatograph solvents

Inverse Size Exclusion Chromatographic (ISEC) Analysis of Solvent Wetted Polymer Supports... 

Experimental. Absorbances of selected polymer and copolymer samples were measured with a Waters 440 ultraviolet absorbence detector equipped with a 254 nm filter, and a Beckman 25 ultraviolet/visible spectrophotometer. The Water s instrument was used on-line with the size exclusion chromatograph (16). The Beckman 25 was used to calibrate and standardize the Water s 440 UV detector. THF was used as standard solvent. The extinction coefficients were estimated from absorbance measurements at several polymer concentrations. The standard deviation for the absorbance measurements was typically . 001 Au for replicates on the same sample. All measurements were done at room temperature. 

Anionic thesis of macromonomer of 1,1-diphenylethylene-type unit canying amino group has been performed in a variety of solvents. The product was characterized a combination of H NMR spectroscopic and size exclusion chromatographic analysis. Based on the UV/Visible spectroscopic analysis, the crossover reaction of /i-butyllithium (n-BuLi) with l-[4-bis(trimethylsilyl>amino]phenyl]-l-phenylethylene was found to be so slow in benzene, but it was completed in the benzene/THF mixture within 2 h. The i thesis of macromonomer of thel,l-diphenylethylene-type unit (over 95 %) canying amine-functional group (maximum 94 %) was successful on the basis of H NMR spectroscopic analysis. 

An analytical TREF system was first described by Wild and Ryle [8], Their system (Fig. 8) used components taken from a Waters model 200 size exclusion chromatograph. The solvent reservoir, degasser and pump from the Waters unit was used as was the refractive index detector system. In place of the SEC oven a temperature programmed oil bath provided the temperature gradients. A 0.2 g polymer sample was loaded in a hot trichlorobenzene solution into a small column packed with 40-60 mesh Chromosorb P. Crystallization was achieved by slow-cooling the polymer solution (0.2 g in 5 ml) in the packed column at a rate of 1.5 K/hour down to room temperature. The temperature rising elution was carried out at a flow rate of 6 ml/min and a rate of temperature rise of 8 K/hour. The refractive index response and the separation temperature were recorded continuously on a two-pen recorder. A calibration curve of methyl content vs. elution... 

Upnmoor and Brunner [7] evaluated a packed column SFC with a light scattering detector using a mobile phase of carbon dioxide modified with methanol for the chromatography of polymer additives. Moulder and co-workers [8] transferred eluent fractions from a packed capillary size exclusion chromatographic (SEC) column using a solvent vented interface to an open tubular CSFC column. The system was evaluated for the analysis of polymer additives. 

During the phase transfer etherification the bisphenols were slowly transferred into the reaction. This slow addition of monomer, the highly reactive haloether chain ends and the flexibility of the formal linkage lead to the formation of cyclic polyfor-mals typical yields = 20 wt%. The cyclics eluted as the low molecular weight tail in the size exclusion chromatograph. Reverse precipitation by the addition of non-solvent to a polymer solution removed the cyclic component (see Figure 2). 

Lau, S. Y. M., Taneja, A. K., and Hodges, R. S., Effects of high-performance liquid chromatographic solvents and hydrophobic matrices on the secondary and quaternary structure of a model protein. Reversed-phase and size exclusion high-performance liquid chromatography, /. Chromatogr., 317, 129, 1984. 

Molecular weight measurements were determined by size exclusion chromatography on a high pressure liquid chromatograph equipped with a differential refracto-meter. A Waters Styragel HR 5 i column set (106 104 500 A) was employed and calibrated with PS standards. THF was used as solvent at a flow rate of 1 ml/min. 

Size exclusion chromatography (SEC) separates molecules based on size in a short analysis time. Unlike other chromatographic techniques, SEC does not retain sample species in the column, the analysis time is fixed, and everything loaded onto the column elutes within a fixed time frame. The application of SEC is limited only to the solubility of the sample in a solvent. Since tetrahydrofuran (THE) is a good solvent for coal liquids, the separation of coal liquids by SEC can be easily achieved. 

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