Fast “hyperlayer” separation development in sedimentation field flow fractionation☆

A simple theoretical model for the size selectivity, S(d), in the lift mode of retention in field-flow fractionation (FFF) is developed on the basis of the near-wall lift force expression. S(d) is made up of two contributions: the flow contribution, S(d,f), arising from the variation of the flow velocity at center of particle due to a change in particle position with particle size, and a slip contribution, S(d,s), arising from the concomitant change in the extent of retardation due to the presence of a nearby channel wall. The slip contribution is minor, but not negligible, and amounts to 10-20% of the overall size selectivity. It contributes to reduce S(d) in sedimentation FFF but to enhance it in flow FFF. S(d) would steadily increase with particle size if the flow profile was linear (Couette flow). Because of the curvature of the flow profile encountered in the classical Poiseuille flow, S(d) exhibits a maximum at some specific particle size. The model predicts a significant difference in S(d) between sedimentation FFF and flow FFF, arising from the different functional dependences of the field force with particle size between these two methods. The predictions are in good agreement with the various S(d) values reported in the literature in both sedimentation and flow FFF. On the basis of the model, guidelines are given for adjusting the operating parameters (carrier flow rate and field strength) to optimize the size selectivity. Finally, it is found that S(d) generally decreases with decreasing channel thickness.

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“…Experimental S d values reported in the literature vs reference number: (a) SdFFF data; ,,− (b) FlFFF data. ,− …”

Section: Resultsmentioning

confidence: 99%

Size Selectivity in Field-Flow Fractionation: Lift Mode of Retention with Near-Wall Lift Force

Martin

Beckett

2012

J. Phys. Chem. A

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“…As shown in the gure, ow FFF achieved an appropriate separation in normal mode for particles up to approximately 506 nm in size; however, for the particles of 1005 nm size and greater, the sterichyperlayer interaction in the ow FFF channel membrane caused the larger particles to elute faster than the smaller particles. [19][20][21] For example, the 1005 nm PS-latex particles eluted slightly slower than the 300 nm PS-latex particles, as shown in the gure.…”

Section: Haruhisa Kato * and Ayako Nakamuramentioning

confidence: 99%

Separation of nano- and micro-sized materials by hyphenated flow and centrifugal field-flow fractionation

Kato

Nakamura

2014

Anal. Methods

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“…The carrier solution used was 0.001% FL70 (Fisher Scientific, France), commonly used in the FFF experiments, to avoid the accumulation of impurities in the FFF channel. 36,37 The characterisation of colloidal soil samples by SdFFF was performed using the normal mode, avoiding interference due to the steric mode (co-elution of smaller and larger particles). 38 The soil <1 mm fraction was extracted by following the same procedure adopted for the fraction <2 mm with the exception of using a centrifugation time of 4.13 minutes.…”

Section: Particle Distribution Analysis and Hg Determinationmentioning

confidence: 99%

Colloidal mercury (Hg) distribution in soil samples by sedimentation field-flow fractionation coupled to mercury cold vapour generation atomic absorption spectroscopy

et al. 2012

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Diverse analytical techniques are available to determine the particle size distribution of potentially toxic elements in matrices of environmental interest such as soil, sediments, freshwater and groundwater. However, a single technique is often not exhaustive enough to determine both particle size distribution and element concentration. In the present work, the investigation of mercury in soil samples collected from a polluted industrial site was performed by using a new analytical approach which makes use of sedimentation field-flow fractionation (SdFFF) coupled to cold vapour generation electrothermal atomic absorption spectroscopy (CV-ETAAS). The Hg concentration in the SdFFF fractions revealed a broad distribution from about 0.1 to 1 μm, roughly following the particle size distributions, presenting a maximum at about 400-700 nm in diameter. A correlation between the concentration of Hg in the colloidal fraction and organic matter (O.M.) content in the soil samples was also found. However, this correlation is less likely to be related to Hg sorption to soil O.M. but rather to the presence of colloidal mercuric sulfide particles whose size is probably controlled by the occurrence of dissolved O.M. The presence of O.M. could have prevented the aggregation of smaller particles, leading to an accumulation of mercuric sulfides in the colloidal fraction. In this respect, particle size distribution of soil samples can help to understand the role played by colloidal particles in mobilising mercury (also as insoluble compounds) and provide a significant contribution in determining the environmental impact of this toxic element.

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Fast “hyperlayer” separation development in sedimentation field flow fractionation☆

Cited by 7 publications

References 29 publications

Size Selectivity in Field-Flow Fractionation: Lift Mode of Retention with Near-Wall Lift Force

Size Selectivity in Field-Flow Fractionation: Lift Mode of Retention with Near-Wall Lift Force

Separation of nano- and micro-sized materials by hyphenated flow and centrifugal field-flow fractionation

Colloidal mercury (Hg) distribution in soil samples by sedimentation field-flow fractionation coupled to mercury cold vapour generation atomic absorption spectroscopy

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