Time-delayed exponential field-programmed sedimentation field flow fractionation for particle-size-distribution analyses

Kirkland, J. J.; Rementer, S. W.; Yau, Wallace W.

doi:10.1021/ac00235a005

Cited by 78 publications

(37 citation statements)

References 4 publications

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“…Earlier we reported results obtained with this commercial instrument together with results from quasi elastic light scattering spectroscopy (QELS) and transmission electron microscopy (TEM) [ll, 121. We found the sizes calculated from SFFF some 10-20% smaller than those from QELS or TEM. This is in contrast to several other articles [8][9][10]171 where better agreement has been reported. We, therefore, thoroughly checked our instrument, that is, we measured channel dimensions and inlet and outlet volumes and made some modifications to the software from Du Pont.…”

Section: Introductioncontrasting

confidence: 99%

Evaluation of a Commercial Instrument of Sedimentation Field Flow Fractionation

Mori

Merkus

Scarlett

1990

Part & Part Syst Charact

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The analysis of particles in the sub‐micron range by sedimentation field flow fractionation (SFFF) is not new, but its commercial exploitation is recent. This inevitably will lead to a rigorous evaluation of the technique by many laboratories, for many applications, as well as to rapid development. This paper describes first an evaluation of the new commercial instrument using both ideal and real materials. These experiments lead to a discussion of the software package and of the influence of experimental conditions. A particular study is described of the combination of the SFFF technique with that of quasi‐elastic light scattering. The paper concludes that SFFF now offers the technology for realistically measuring particle size distributions at high resolution in the submicron size range. The analysis time is in the order of one hour, but can be reduced at the expense of resolution.

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Section: Introductioncontrasting

confidence: 99%

Evaluation of a Commercial Instrument of Sedimentation Field Flow Fractionation

Mori

Merkus

Scarlett

1990

Part & Part Syst Charact

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“…For reasons that we do not have to go into here, the field-decay program for analysis of a polydisperse sample should ideally approach zero field asymptotically . Such programs include the exponential and power programs (Kirkland et al 1981;Giddings et al 1987;, 1991, 1994. We choose the power program for its flexibility and potential for uniform relative resolution over a wide range.…”

Section: (B) Field and Field-gradient Programming For Magnetic Field-flow Fractionationmentioning

confidence: 99%

“…This may be referred to as the equivalent spherical core diameter where it is only the core material that interacts with the field, and this material may be finely divided and distributed within the total volume of the particle. During the early development of SdFFF, it was quickly realized that because of the high selectivity, a constant field is not suitable for the analysis of polydisperse samples, and it is necessary to use a programmed field decay during sample elution (Yang et al 1974;Kirkland et al 1981;Giddings et al 1987;. This is also true of MgFFF, and it is necessary to program the decay of field and field gradient using a quadrupole electromagnet and computer control of the current supply.…”

Section: Introductionmentioning

confidence: 99%

Characterization of magnetic nanoparticles using programmed quadrupole magnetic field-flow fractionation

Williams

Carpino

Zborowski

2010

Phil. Trans. R. Soc. A.

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Quadrupole magnetic field-flow fractionation is a relatively new technique for the separation and characterization of magnetic nanoparticles. Magnetic nanoparticles are often of composite nature having a magnetic component, which may be a very finely divided material, and a polymeric or other material coating that incorporates this magnetic material and stabilizes the particles in suspension. There may be other components such as antibodies on the surface for specific binding to biological cells, or chemotherapeutic drugs for magnetic drug delivery. Magnetic field-flow fractionation (MgFFF) has the potential for determining the distribution of the magnetic material among the particles in a given sample. MgFFF differs from most other forms of field-flow fractionation in that the magnetic field that brings about particle separation induces magnetic dipole moments in the nanoparticles, and these potentially can interact with one another and perturb the separation. This aspect is examined in the present work. Samples of magnetic nanoparticles were analysed under different experimental conditions to determine the sensitivity of the method to variation of conditions. The results are shown to be consistent and insensitive to conditions, although magnetite content appeared to be somewhat higher than expected.

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“…Many different fields have been utilized for FFF including gravitational [4], centrifugal [5][6][7], thermal gradient [8,9], electrical [10,11], and magnetic [12,13]. Any field that interacts with a sample material property to drive the particles across the channel thickness may be used.…”

Section: Introductionmentioning

confidence: 99%

Retention ratio and nonequilibrium bandspreading in asymmetrical flow field-flow fractionation

Williams

2015

Anal Bioanal Chem

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In asymmetrical flow field-flow fractionation (As-FlFFF), only the membrane-covered accumulation wall is permeable to fluid; the opposite channel wall is impermeable. Fluid enters the channel at the inlet and exits partly through the membrane-covered accumulation wall and partly through the channel outlet. This means that not only does the volumetric channel flow rate decrease along the channel length as fluid exits through the membrane but also the cross-channel component to fluid velocity must approach zero at the impermeable wall. This dependence of cross-channel fluid velocity on distance across the channel thickness influences the equilibrium concentration profile for the sample components introduced to the channel. The concentration profile departs from the exponential profile predicted for the ideal model of field-flow fractionation. This influences both the retention ratio and the principal contribution to bandspreading--the nonequilibrium contribution. The derivation of an equation for the nonequilibrium bandspreading parameter χ in As-FlFFF is presented, and its numerical solution graphed. At high retention, it is shown that the solutions for both retention ratio R and χ converge on those for the ideal model, as expected. At lower levels of retention, the departures from the ideal model are significant, particularly for bandspreading. For example, at a level of retention corresponding to a retention parameter λ of 0.05, R is almost 4% higher than for the ideal model (0.28047 as compared to 0.27000) but the value of χ is almost 60% higher. The equations presented for both R and χ include a first-order correction for the finite size of the particles--the steric exclusion correction. These corrections are shown to be significant for particle sizes eluting well before steric inversion. For example, particles of half the inversion diameter are predicted to elute 25% slower and to show almost 40% higher bandspreading when steric effects are not accounted for. The work presented contributes to the fundamental theory of As-FlFFF and allows quantitative prediction of both retention and bandspreading at all levels of retention.

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Time-delayed exponential field-programmed sedimentation field flow fractionation for particle-size-distribution analyses

Cited by 78 publications

References 4 publications

Evaluation of a Commercial Instrument of Sedimentation Field Flow Fractionation

Evaluation of a Commercial Instrument of Sedimentation Field Flow Fractionation

Characterization of magnetic nanoparticles using programmed quadrupole magnetic field-flow fractionation

Retention ratio and nonequilibrium bandspreading in asymmetrical flow field-flow fractionation

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