High-speed size characterization of chromatographic silica by flow/hyperlayer field-flow fractionation

Ratanathanawongs, S. Kim; Giddings, J. Calvin

doi:10.1016/s0021-9673(01)93988-3

Cited by 40 publications

(22 citation statements)

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“…(This cross flowstream, as it flows across the channel thickness, is responsible for the separation effect observed for flow FFF. 1,2,23 ) Using the OFSC technique, a sample can be loaded into an FFF channel and focused into a narrow band by using two opposing inflows at opposite ends of the channel as shown in Figure 1b. During this step, no flow is permitted to enter or exit through the upper frit wall.…”

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“…The micrographs confirm that a size fractionation has been achieved with smaller particles eluting prior to large particles. Since flow FFF separations are dependent on only the hydrodynamic diameter,23 other physicochemical properties of the sample components are inconsequential and particle size information is readily calculated from the retention times. The river sediment possesses a broad continuous distribution of particles ranging in size from 0.1 to 1.2 µm.…”

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Particle Size Analysis of Dilute Environmental Colloids by Flow Field-Flow Fractionation Using an Opposed Flow Sample Concentration Technique

1998

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An on-line concentration method has been developed for the analysis of dilute suspensions of macromolecules and particles by flow field-flow fractionation (FFF). This method, termed opposed flow sample concentration (OFSC), uses two opposing flowstreams to focus sample into a narrow band near the inlet of the flow FFF channel. Large sample volumes (up to 1 L) have been successfully loaded, concentrated, and separated in a 1 mL volume flow FFF channel. Concentration factors as high as 10(5) have been achieved. The effectiveness of OFSC flow FFF was demonstrated using mixtures of monodispersed standards such as proteins and polystyrene latex beads. Retention times, peak areas, and resolution are comparable for a 10 mL and a typical 10 microL injection volume. The applicability of the method to environmental studies was demonstrated by a separation of river water colloids.

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Particle Size Analysis of Dilute Environmental Colloids by Flow Field-Flow Fractionation Using an Opposed Flow Sample Concentration Technique

1998

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“…Our numerous experiments with both steric FFF (unpublished) and the related operating mode of hyperlayer FFF (15) ©1991 American Chemical Society have shown that a plot of log tr vs log d (where tr is retention time and d is particle diameter) is approximately linear over a wide diameter range for polystyrene latex spheres. This linear relationship, or linear calibration curve, can easily be made the basis for obtaining particle size distributions from a sedimentation/steric FFF fractogram, providing the particles are polystyrene spheres or other particles of the same density.…”

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Particle size distribution by sedimentation/steric field-flow fractionation: development of a calibration procedure based on density compensation

Giddings¹,

Moon²,

Williams³

et al. 1991

Anal. Chem.

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Because of the important but mathematically complex role played by hydrodynamic lift forces in sedimentation/steric FFF, applied generally to particles greater than 1 micron in diameter, retention cannot readily be related to particle diameter on the basis of simple theory. Consequently, empirical calibration is needed. Unfortunately, retention is based on particle density as well as size so that a purely size-based calibration (e.g., with polystyrene latex standards) is not generally valid. By examining the balance between driving and lift forces, it is concluded that equal retention will be observed for equal size particles subject to equal driving forces irrespective of particle density. Therefore by adjusting the rotation rate to exactly compensate for density, retention can be brought in line with that of standards, a conclusion verified by microscopy. Linear calibration plots of log (retention time) versus log (diameter) can then be used. This approach is applied to two glass bead samples (5-30 and 5-50 microns) using both a conventional and a pinched inlet channel. The resulting size distribution curves are self consistent and in good agreement with results obtained independently.

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“…Caldwell et al [13] studied in 1984, a strong dependence of the retention ratio of human and animal cells on the flow rate and field strength, observed already earlier [14], and they explained this behavior by the lift forces emerging in sedimentation/"steric" FFF. Ratanathanawongs and Giddings [15] described in 1989 the active use of the focusing mechanism in flow FFF for high-speed characterization of silica particles with the conscious exploitation of the lift forces leading to the focusing phenomena.…”

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Micro-thermal focusing field-flow fractionation

Janča

Ananieva

Menshikova

et al. 2004

Journal of Chromatography B

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High-speed size characterization of chromatographic silica by flow/hyperlayer field-flow fractionation

Cited by 40 publications

References 20 publications

Particle Size Analysis of Dilute Environmental Colloids by Flow Field-Flow Fractionation Using an Opposed Flow Sample Concentration Technique

Particle Size Analysis of Dilute Environmental Colloids by Flow Field-Flow Fractionation Using an Opposed Flow Sample Concentration Technique

Particle size distribution by sedimentation/steric field-flow fractionation: development of a calibration procedure based on density compensation

Micro-thermal focusing field-flow fractionation

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