Size-exclusion chromatography apparatus

Size-exclusion chromatography (SEC) has been used to characterize the unimer-micelle distribution. However, SEC is not an absolute method and thus requires calibration. Since it is practically impossible to calibrate a SEC apparatus for the unimers and micelles formed by a block copolymer, only indicative MW values can be obtained. Moreover, several authors have noted a strong perturbation of the unimer-micelle equilibrium during SEC experiments even when interaction of the material with the SEC column was minimized [4,61,62],... 

NMR spectra were recorded, in CDCl with DRX-500MHz spectrometer (TMS as the reference). Size exclusion chromatography (SEC) was performed using a LDC Analytical refractoMonitor IV instrument [RI detector, two columns SDV 8x3(X) (5 pm and 104 A porosity) and SDV 8 x 300 (5 pm and 100 A porosity), eluent - toluene (0.7 ml/min)]. Parallel measurements were effected with Wyatt Optilab 903 apparatus... 

Conventional Size Exclusion Chromatography, SEC, was performed on a Spectra Physics apparatus with two PL gel columns (5 pm particle size, 300 mm length, one with 50 A and one with 100 A pore size) and a Styragel HR2 column (7.8mm internal diameter x 300mm length). The detection was achieved with a SP8430 differential refractometer. The tolnene was elnted at a flow rate of 0.8mL.min . 

H and Si NMR spectra were recorded on a Brnker Avance 300 spectrometer respectively at 300.13 and 75.6MHz at room temperatnre. CDClj and toluene were used as solvents. For Si NMR, Cr(acac)3 (0.03 M) was added in the tube and a delay between pulses of 20 s was set. IR spectra were recorded on a Perkin-Ehner IR ET 1760-X. The average molecnlar weight of the linear polymers was determined by size exclusion chromatography in TFIF (flow rate l.OmL.min" ) on an apparatus equipped with a Waters refractive index detector, a Waters column pack (Ultrastyra-gel 10, 10 100 A) and a Minidawn Wyatt light scattering detector. 

For the purpose of molecular weight determination 10 g titanium dioxide (rutile) was grafted with ACTU in the same way as were the plates. Polymerization of styrene was carried out as previously the polymer-covered rutile was thoroughly extracted with toluene in a Soxhlet apparatus. Polystyrene was then detached fi jm the Ti02 particles as shown in Scheme 3 and subjected to molecular weight measurements by size exclusion chromatography (SEC), which gave... 

Size Exclusion Chromatography. Exclusion chromatography was carried out on an apparatus comprised of a Minipump (Milton Roy), a model 7012 injector (Rheodyne) equipped with a 100-pl loop, an R401 differential refractometer (Waters), and a Model 153 UV detector, X,=254 nm (Altex). A Superose-6 column (30 cm x 1 cm OD)(Pharmacia) was eluted at 0.53 ml/min.. Column efficiency, determined with D2O, was at least 12,000 plates/meter. 

Size Exclusion Chromatography (SEC) is widely used technique polymer characterization. The standard configuration of a SEC apparatus consists of three parts (/-5), viz., a solvent-delivery system (equipped widi an injection port), the columns, and a differential refractive index (RI) detector. This basic configuration can be modified by adding an additional detector, either in series or in parallel to the RI detector (J-5). The second detector can be a viscometer (2), a concentration detector (3), an UV detector (4) or a Light Scattering (LS) device (5),... 

Thus calibration of the apparatus with, for example, polystyrene standards with known values of K and a in the particular solvent at a particular temperature permits the absolute molecular mass to be calculated via the universal calibration method [9]. A further advantage of the detector is its ability to be used at temperatures up to 150°C, thus permitting the analysis of polyolefins. The study of branching in polymers is also possible with this system. This new detector probably represents the most significant advance in detectors for size exclusion chromatography in recent years. 

Reversed-phase chromatography and reversed-phase ion-pair chromatography Mixed mode chromatography Size-exclusion chromatography Practical Considerations Apparatus Colunrn Eluants... 

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