Practical implications of ionic strength effects on particle retention in thermal field-flow fractionation
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Date
2003-01Author
Shiundu, Paul M
Munguti, Stephen M
Williams, S. Kim Ratanathanawongs
Type
ArticleLanguage
enMetadata
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Modification of ionic strength of an aqueous or non-aqueous carrier solution can have profound effects on the particle retention behavior in thermal field-flow fractionation (ThFFF). These effects can be considered as either advantageous or not depending on the performance criteria under consideration. Aside from the general increase in retention time of particulate material (latexes and silica particles), our experiments indicate improvement in resolution with increases in electrolyte concentration. Absence of an electrolyte in the carrier solution causes deviations from the theoretically expected linear behavior between the retention parameter l (a measure of the extent of interaction between the applied field and the particle) and the reciprocal temperature drop across the channel walls. A negative interaction parameter d of about 20.170 was determined for 0.105- and 0.220-mm polystyrene (PS) latex particles suspended in either a 0.25 or a 1.0 mM TBAPcontaining acetonitrile carrier and for 0.220 mm PS in 0.50 and 1.0 mM NaCl-containing aqueous medium. This work also demonstrates that optimum electrolyte concentrations can be chosen to achieve reasonable experimental run-times, good resolution separations, and shifts in the steric inversion points at lower field strengths, and that too high electrolyte concentrations can have deleterious effects such as band broadening and sample loss through adsorption to the channel accumulation surface. The advantages of using ionic strength rather than field strength to effect desired changes are lowered power consumption and possible application of ThFFF to high temperature-labile samples.
URI
http://www.sciencedirect.com/science/article/pii/S0021967302017697http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/38163
http://www.ncbi.nlm.nih.gov/pubmed/12564677
Citation
Journal of Chromatography A Volume 984, Issue 1, 10 January 2003, Pages 67–79Publisher
Department of Chemisty, University of Nairobi
Subject
Thermal field-flow fractionationIonic strength
Interaction parameter
Particle retention
Field-flow fractionation
Steric inversion diameter
Diameter-based selectivity
Description
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