Mechanistic Study of Electrical Field Flow Fractionation. 2. Effect of Sample Conductivity on Retention

Palkar, Saurabh A.; Schure, Mark R.

doi:10.1021/ac970014w

Cited by 15 publications

(22 citation statements)

References 15 publications

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“…Diffusion has significant negative impacts on CyElFFF, and it is likely that allowing more time for diffusion to act allows greater dispersion to occur. This dispersion is further increased because of reduced local fields in the compact particle layers near the wall associated with charge shielding [22]. The experimental results further show that negative offset voltages mirror positive offset voltages in their effect on plate numbers, similar to the results for retention.…”

Section: Effect Of Offset Voltage On Band Broadeningsupporting

confidence: 72%

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Optimization of cyclical electrical field flow fractionation

2010

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Cyclical electrical field flow fractionation (CyElFFF) is a variation on electrical field flow fractionation (ElFFF) where cyclical electrical fields are used instead of steady DC fields to increase the effective field experienced by particles in the flow channel. Even though the effective field increases more than 20-fold compared to normal ElFFF, the retention and resolution in CyElFFF has not been shown to be better than in ElFFF. In this paper we report how one can optimize operational parameters in CyElFFF to obtain good retention and resolution in CyElFFF. The effects of offset voltage, frequency, flowrate, concentration of particles and sample size on retention, resolution and retained peak/void peak ratio have been observed. The results obtained from these experiments were analyzed and suggestions have been made to improve both retention and resolution. A 4-fold improvement in retention without a significant increase in band broadening is reported.

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Section: Effect Of Offset Voltage On Band Broadeningsupporting

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Optimization of cyclical electrical field flow fractionation

2010

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“…(2), while the effective retention parameter can be calculated using Eq. (11). Essentially, the nominal values correspond to a 100% effective applied electric field and will be always higher than the effective retention parameter values.…”

Section: Simulation Resultsmentioning

confidence: 98%

“…All of the theoretical analysis so far assumes that all of the applied electric field in a CyElFFF system is effective in moving particles inside the channel, which is not true due to shielding of the applied field by the electrical double layer developed at the electrode-carrier interface [10,11]. Thus, CyElFFF models based on these equations lead to poor prediction of elution times.…”

Section: Assumptions and Backgroundmentioning

confidence: 99%

Improved theory of cyclical electrical field flow fractionation

2006

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Previously reported theories for cyclical electrical field flow fractionation (CyElFFF) are severely limited in that they do not account for diffusion, steric, or electric double layer effects. Experiments have shown that these theories overpredict the retention of particles in CyElFFF. In this work, we present a model for prediction of steric, diffusion, and electrical effects. The electrical double layer effects are treated using a lumped electrical circuit model that accounts for the field shielding by the electrical double layer formed at the electrode-carrier interface. The electrical effects are shown to dominate retention times and outweigh the contributions of diffusion and particle size. Detailed results from the simulations are presented in this work, and a comparison between the theoretical and experimental results obtained from the retentions of polystyrene particle standards is presented in this paper. The models are shown to correctly predict the retention of the polystyrene standards in CyElFFF with a reasonable error, while existing models are shown to have significant failings.

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“…Cow1)leted Cross Section et al 12 and numerical solution is not generally required if an effective field value is assumed, even for a sample with anisotropic diffusion. A more complete understanding of the inner workings of an ElFFF channel has not yet been presented, though empirical models have been presented by Kantak et al 10,13 .…”

Section: Theorymentioning

confidence: 99%

Nanoparticle analysis using microscale field flow fractionation

Gale

Sant

2007

Microfluidics, BioMEMS, and Medical Microsystems V

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Microscale electrical field flow fractionation (FFF) has shown significant progress since it was first reported in early 1997. The first electrical FFF systems were lucky to function for more than a few days and generated only minimal levels of retention and separation, while current systems now easily function for years and can generate multicomponent nanoparticle separations. A variety of microscale FFF systems have now been reported including: multiple versions of normal electrical FFF (ElFFF), cyclical electrical FFF (using oscillating fields), dielectrophoretic FFF, thermal FFF, and a combined thermal-electric FFF channel. Related microscale electrical SPLITT systems have also been demonstrated. Microscale ElFFF systems have been used to analyze and separate nanoparticles, DNA, proteins, cells, viruses, liposomes, large polymers, and other materials. ElFFF clearly improves upon system miniaturization due to the reduction in sample and carrier volumes, analysis times and more notably an increase in the separation resolution with a reduction in analysis times. Other advantages of miniaturized FFF include: parallel processing with multiple separation channels, batch fabrication with reduced costs, high quality manufacturing, and potentially disposable systems. Additionally, the possibility of on-chip sample injection, detection and signal processing favors the microfabrication of FFF systems.

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Mechanistic Study of Electrical Field Flow Fractionation. 2. Effect of Sample Conductivity on Retention

Cited by 15 publications

References 15 publications

Optimization of cyclical electrical field flow fractionation

Optimization of cyclical electrical field flow fractionation

Improved theory of cyclical electrical field flow fractionation

Nanoparticle analysis using microscale field flow fractionation

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