Field-flow fractionation retention parameter

Provided that the correction for the zone broadening should not be applied, the first step in the data treatment is to convert the retention volumes (or the retention ratios R) into the corresponding molecular or particulate parameter, characterizing the fractionated species. Whenever the zone broadening correction procedure has to be applied, the data treatment protocol is modified, as described in the entry Zone Dispersion in Field-Flow Fractionation. 

The retention ratio R in polarization FFF is related to the retention parameter A (see the entry Field-Flow Fractionation Fundamentals) by... 

In field-flow fractionation (FFF), retention can be related through a well-defined equation to the applied held and governing physicochemical parameters of the analyte. Therefore, in principle, FFF is a primary measurement technique that does not require calibration, but only if the governing physiochemical parameters are either the analyte parameters of interest or their relationship to the parameter of interest (such a molecular weight) is well deflned. 

Janca, J. Martin, M. Influence of operational parameters on retention of ultra-high molecular weight polystyrenes in thermal field-flow fractionation. Chromatographia 1992,34,125. Semyonov, S.N. Kuznetsov, A. A. Zolotaryov, P.P. Theoretical examination of focusing field-flow ftactionation. J. Chromatogr. 1986, 364, 389. 

Regazzetti, A. Hoyos, M. Martin, M. Influence of operating parameters on the retention of chromatographic particles by thermal field-flow fractionation. Anal. Chem. 2004,... 

Figure 7.3.21. Field-flow fractionation (FFF). (a) Basic configuration of field-flow fractionation device and the detector response to a sample, (b) Retention ratio of species i vs. retention parameter X. (c) Schematic for flow field-flow fractionation with a cros ow. (d) Fhysical configuration/dimensions of a FFF channel with inlet/outlet. (e) Configuration of the channel in sedimentation FFF. (After Giddings (1993).)...

Flow FFF is the most universal method because the cross-flow field acts on all fractionated species in the same manner and the separation is due to the differences in diffusion coefficients [10]. The channel, schematically demonstrated in Fig. 2c, is formed between two parallel semipermeable membranes. The carrier liquid can permeate through the membranes but not the separated species. The retention parameter A is related to the diameter dp of the separated species by... 

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