Zone broadening and dilution in rectangular and trapezoidal asymmetrical flow field-flow fractionation channels

Abstract

A new trapezoidal geometry of the asymmetrical flow fieldflow fractionation (FFF) channel Introduces an additional means to regulate the longitudinal flow velocity. The trapezoidal geometry, where the breadth decreases on going toward the channel outlet, makes It possible to level out the steep linear velocity gradients that can appear In the rectangular channels. Equations for the channel flow velocity gradient and the void time are derived. In addition, an equation for the nonequilibrium plate height Is derived for asymmetrical channels. The equation suggests that the same efficiencies should be obtained In asymmetrical as In the original symmetrical channels under similar flow conditions. The relative peak dilution occurring In channels of different designs Is evaluated. The results favor the trapezoidal versus the rectangular channel and asymmetrical versus symmetrical channels. The plate numbers calculated from the derived equations were compared with those found experimentally. The latter were found to deviate from the calculated numbers at high retention levels. Approximately 2600 plates have been reached.

Protein aggregation: Pathways, induction factors and analysis

“…This type of channel shape versus a rectangular shape advantageously allows an extra means to control the longitudinal flow velocity, where the breadth decreases continuously towards the channel outlet, which 135 creates a possibility to level out the steep linear velocity gradients that can materialize in the rectangular channel. 122 The ultrafiltration membrane also needs to be carefully considered as the cut-off range and molecular interaction with the filter material may significantly influence the potential sample loss and recovery. The membrane protein interaction is most pronounced during the high cross-flow conditions and consequently some adjustment of elution solvent composition may be needed which could in turn induce conformational changes of proteins or influence the distribution of noncovalent aggregates.…”

Characterization of phosphatidylcholine/polyethylene glycol‐lipid aggregates and their use as coatings and carriers in capillary electrophoresis

“…The AsFlFFF channel was constructed in-house in a manner similar to that of other groups [18][19][20][21]. A regenerated cellulose acetate ultrafiltration membrane with a molar mass cut-off of 10 kDa (DSS-RC70PP, Nakskov, Denmark) was laid on top of the porous frit.…”

Asymmetrical flow field‐flow fractionation coupled to multiangle laser light scattering detector: Optimization of crossflow rate, carrier characteristics, and injected mass in alginate separation

“…(1) for every point of the distribution, by employing the void time corresponding to each crossflow (calculated according to the FFF theory for asymmetrical systems and trapezoidal channels [30]). The weight-average hydrodynamic radius, R Hw , was calculated as follows:…”