Field-flow fractionation molecular weight determination

Lyven, B., Hassellov, M., Haraldsson, C. and Turner, D.R. (1997) Optimisation of on-channel preconcentration in flow field-flow fractionation for the determination of size distributions of low molecular weight colloidal material in natural waters. Anal. Chim.Acta, 357, 187-196. 

Fig. 1 Instrumental schematics of FLFFF with on-channel preconcentration showing the three different steps. The first involves emptying of the sample loop into either the forward or backward flows and subsequent focusing of the sample material at the focusing point. In the next step, the samples are allowed to relax at the equilibrium position by applying cross-flow only, and then the channel flows are switched on and elution is commenced. Source From Optimisation of on-channel preconcentration in flow field-flow fractionation for the determination of size distributions of low molecular weight colloidal material in natural waters, in Anal. Chim. Acta. ...

Beckett, R., Jue, Z. and Giddings, J. C. (1987). Determination of molecular weight distributions of fulvic and humic acids using flow field-flow fractionation, Environ. Sci. Technol., 21, 289-295. 

Schimpf ME (1995) Determination of molecular weight and composition in copolymers using thermal field-flow fractionation combined with viscometry. In Provder T, Barth HG, Urban MW (eds) Chromatographic characterization of polymers hyphenated and multidimensional techniques. American Chemical Society, Washington, DC, pp 183-196... 

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

The main purpose of the detector in a field-flow fractionation (FFF) system is to quantitatively determine particle number, volume, or mass concentrations in the FFF size-sorted fractions. Consequently, a number, volume, or mass dependent size distribution of the sample can be derived from detection systems applied to FFF [e.g., (UV-Vis) fluorescence, refractive index, inductively coupled plasma ionization mass spectrometry (ICPMS)]. Further, on-line light scattering detectors can provide additional size and molecular weight distributions of the sample. 

Ftg- 2 Elemental size distributions of the colloidal material in a freshwater sample as given from an FLFFF coupled to ICPMS. A UV detector is placed on line prior to the ICPMS and the UV size distribution is included. The signals are plotted as a function of retention time, hydrodynamic diameter (from FFF theory), and molecular weight (from standardization with PSS standards). Source From Determination of continuous size and trace element distribution of colloidal material in natural water by on-line coupling of flow field-flow fractionation with ICMPS, in Anal. Chem. J... 

Lee, S. Molnar, A. Determination of molecular weight and gel content of natural rubber using thermal field-flow fractionation. Macromolecules 1995, 28, 6354. 

Kim, W.-S. Elurrr, C.H. Molnar, A. Yu, J.-S. Lee, S. Repeatability and reproducibility of thermal field flow fractionation in Molecular weight determination of processed natural rubber. Analyst 2006,131 (3), 429-433. 

Jeon, S.J. Schimpf, M.E. Cross-fractionation of copolymers using SEC and thermal field-flow fractionation for determination of molecular weight and composition. In Chromatography of Polymers Hyphenated and Midtidimensiorud Techniques, Provder, T., Ed. ACS Symposium Series No. 731, Ch ter 10 ACS Publications Washington, DC, 1999 141-161. 

Several other techniques have been applied to the study of physical properties of HS. Field-flow fractionation (described in Section 7.6.3) has been applied to the study of size distribution of HS (Beckett, Jue, and Giddings 1987 Lead et al. 2000). Electrophoresis has been largely applied in the separation of charged components of HS, but was employed only a few times for the determination of molecular weight and size of HS (Senesi and Loffredo 1998). The retardation of macromolecules in a gel media under an applied electric field is related to the size of the pores and the migrating molecules. The retardation coefficient can be related to the molecular weight by... 

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. 

Flow field - flow fractionation has been used" to fractionate polystyrene and Kirkland and Rementer" used thermal field flow fractionation using Mark Houweq constants to determine the molecular weight distribution of polystyrene and poly methylstyrene. 

Kirkland and Rementer" determined the molecular weight distribution of polyacrylates using thermal field flow fractionation using Mark Houweg constants. 

Kirkland et al" determined the molecular weight distribution of polyethylene oxide in the 10 to 2 x 10 molecular weight range by field flow fractionation. 

Field flow fractionation has been used to fractionate and determine the molecular weight of sodium polystyrene sulphonate" and polystyrene sulphonate (molecular weight range 6.6 x 10 to 6.9 x 10 ). 

Cooper, A. R. (ed.), Determination of Molecular Weight , Wiley, New York, 1989. The status of the older methods of molecular weight determination and the theory and applications of some newer methods—phase distribution chromatography, field flow fractionation, supercritical fluid chromatography, among others—are reviewed. 

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