Fractionation thermal field flow

In thermal field flow fractionation (TFFF), a temperature gradient is applied. The primary potential advantage of this technique is that it can be used to size particles in the range 0.01 pm to 0.001 pm, an order of magnitude smaller than SFFF. Fffractionation market a TFFF polymer fractionator channel module with 286/16 MHz IBM compatible PC, super VGA color monitor workstation to include data acquisition software, hardware and data analysis software. A linear UV detector and single channel high performance pump are optional. 

Kassalainen and Williams [135] coupled thermal field flow fractionation (ThFFF) and matrix-assisted laser desorption/ionisation time-of-flight mass spectroscopy (MALDI-ToF-MS) to yield a powerful combination of techniques for the analysis of polydisperse PS. ThFFF high selectivity and sensitivity to chemical composition were used to separate polydisperse polymers and polymer mixtures into the narrow polydispersity and homogeneous chemical composition fractions essential for MAT.DT-ToF-MS analyses. On the other hand, because it is possible to measure directly using MALDI-ToF-MS, it alleviates the need for polymer standards for ThFFF. Kassalainen and Williams [135] address the coupling of ThFFF and MALDI-ToF-MS and identify compatibility issues. Optimum conditions were determined and developed to maximise the capabilities of the combined technique. Depending on the polymer and the method of matrix-assisted laser desorption/ionisation (MALDI) sample deposition, fractions from 1-10 ThFFF runs were combined for MALDI-ToF-MS analysis. Binary solvents are used to enhance ThFFF retention and resolution of low ( 15 kDa) polymers, and methods developed to allow routine MALDI-ToF-MS analyses of PS polymers up to 575 kDa. Overall, the compatibility of the two techniques was extended from several kilodaltons to several hundred kDa. Polymer 

Cho and co-workers [137] applied temperature gradient interaction chromatography to the separation of stereoregular polyethyl methacrylate according to the tacticity. Three different polyethyl methacrylate samples with differing tacticity and prepared by anionic polymerisation were used. Polymer samples were fractionated by temperature gradient interaction chromatography and by MALDI-ToF-MS. 

and light scattering have been used to determine the MWD of anionically polymerised p-methoxystyrene, p-methylstyrene, p-chlorostyrene, and p-cyano-styrene. ThFFF and SEC/multiangle laser light scattering have been used to study the thermal diffusion coefficients of PS, poly( er -butylstyrene) (PtBS) and PS/PtBS copolymer microgels [138]. The retention behaviour of poly(styrene-co-methyl-methacrylate) and poly(styrene-f -iosprene) in ThFFF and SEC have been studied [139]. SEC fractions of blends and copolymers of PS and polyethylene oxide were cross fractionated by ThFFF [140]. 

Fractions 1-5 were obtained using sample preparation I fractions 6-10 were obtained using  

Reproduced with permission from G.E. Kassalainen and S.K.R. Williams, Analytical  

Kirkland and co-workers have used this technique to determine the MWD of water-soluble polymers including polyethylene oxide in the 10 -2 x 10 molecular weight range, including sodium PS sulfates and dextrans [238]. Also, they applied the techniques using Mark-Houwink constants to PS, polyisoprene, poly-a-methylstyrene, polyacrylates, polyvinyl pyrrolidone, and PVC [238]. 

This technique has also been applied to the fractionation and determination of number-average MWD of anionic and cationic water-soluble polymers such as PS sulfonate (molecular weight 6500-690,000) and polyvinyl pyridine (molecular weight 28,000-240,000) [239]. Schuch and co-workers [240] carried out a field flow fractionation of polyvinyl formamide. 

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Currently, there are several molecular weight separation techniques, such as OTHdC, PCHdC, SEC, thermal field flow fractionation (ThFFF), and sedimentation field flow fractionation (SdFFF). The molecular weight separation range... 

SEC, size exclusion chromatography OTHdC, open tubular hydrodynamic chromatography PCHdC, packed column hydrodynamic chromatography ThFFF, thermal field flow fractionation. 

Venema, E., deLeeuw, P., Rraak, J.C., Poppe, H., Tijssen, R. (1997). Polymer characterization using online coupling of thermal field flow fractionation and hydrodynamic chromatography. J. Chromatogr. A 765(2), 135-144. 

Most data about the Ludwig-Soret effect of polymers in solution have been obtained from thermal field-flow fractionation (TFFF), developed by Giddings and coworkers [17,18]. TFFF is one member of the family of field-flow fractionation techniques, which are all characterized by a laminar flow of the polymer solution or colloidal suspension within a relatively narrow channel. An external field, which may be gravitation, cross-flow, or temperature as in TFFF, is applied... 

Column Parameters in Thermal Field-Flow Fractionation, M. E. Hovingh, G. E. 

Thermal Field-Flow Fractionation Extension to Lower Molecular Weight Separations by Increasing the Liquid Temperature Range Using a Pressurized System, J. C. Giddings, L. K. Smith, and M. N. Myers, Anal. Chem., 47, 2389 (1975). Flow Field-Flow Fractionation A Versatile New Separation Method, J. C. Giddings, F. J. Yang, and M. N. Myers, Science, 193, 1244 (1976). 

Thermal Field-Flow Fractionation Using Supercritical Fluids, J. J. Gunderson and J. 

Comparison of Polymer Resolution in Thermal Field-Flow Fractionation and Size Exclusion Chromatography, J. J. Gunderson and J. C. Giddings, Anal. Chim. Acta, 189, 1 (1986). 

Myers MN, Chen P, Giddings JC (1993) Polymer separation and molecular-weight distribution by thermal field-flow fractionation. In Provder T (ed) Chromatography of polymers characterization by SEC and FFF. American Chemical Society, Washington, DC, pp 47-62... 

Giddings JC, Kumar V, Williams PS, Myers MN (1990) Polymer separation by thermal field-flow fractionation high speed power programming. In Craver CD, Provder T (eds) Polymer characterization physical properties, spectroscopic, and chromatographic methods. American Chemical Society, Washington, DC, pp 1-21... 

Schimpf ME (1987) Characterization of polymers and their thermal diffusion by thermal field-flow fractionation. PhD Thesis, University of Utah, USA... 

Determination of Molecular Weight and Size of Ultrahigh Molecular Weight Polymers Using Thermal Field-Flow Fractionation and Light Scattering... 

The early research of Myers et al. [1,2] shows that polymer thermal field-flow fractionation (ThFFF) retention and thermal diffusion are solvent dependent. Recently, Sisson and Giddings [3] indicated that polymer ThFFF retention could be increased by mixing solvents. Rue and Schimpf [4] extended the molecular-weight range that can be retained by ThFFF to much lower molecular weights (<10 kDa) by using solvent mixtures without using extreme experimental conditions. There are several other reports on the effect of solvents on polymer retention, selectivity, and the universal calibration in FFF in last few years [5]. 

The retention of polymer molecules in thermal field-flow fractionation is determined by the diffusion coefficient and the thermal diffusion coefficient Dj, illustrated approximately by [8]... 

Thermal FFF (thermal field-flow fractionation) is an elution-type separation technique applicable to the characterization of various synthetic organic polymers with molecular weights higher than about 10 [1], In thermal FFF, a dilute solution of polymer sample is injected into a thin ribbon-shaped flow channel across which an external field (in the form of a temperature gradient) is applied. Under the influence of the temperature gradient, different components of the sample are carried down the channel at different velocities, leading to the elution of different components at different times and separation is achieved. 

Thermal field-flow fractionation (TFFF) belongs to the historically oldest subtechniques of FFF. It is based on the principle of thermal diffusion. In early works... 

Edwards TL, Gale BK, Frazier AB (2002) A microfabricated thermal field-flow fractionation system. Anal Chem 74(6) 1211-1216... 

Thermophoresis is applied in industry for the separation of (large) molecules or small particles from their solvent in the so-called thermal field-flow fractioning (TFFF) [13]. A downscaled version of this process to microscopic scales demonstrated thermophoretic separation on microscopic scales [14, 15]. The advantage of using the very small confinement in a microfluidic device is that the separation times can be reduced, so that thermophoretic separation can be used. Braun and Libchaber [16] use a combination of thermophoresis and convection to concentrate DNA samples. The disadvantage of this approach is that it is a batch process. 

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