Capillary magnetic field flow fractionation and analysis of magnetic nanoparticles

Andrew H. Latham, Rafael S. Freitas, Peter Schiffer, Mary Elizabeth Williams

Research output: Contribution to journalArticlepeer-review

87 Scopus citations


This paper reports the purification and analysis of magnetic nanoparticles using capillary magnetic field flow fractionation, which utilizes an applied magnetic field oriented orthogonal to the capillary flow. To validate this approach as a separation method for nanometer-scale particles, samples of magnetic nanoparticles composed of either γ-Fe2O3 (maghemite) or CoFe2O4 with average diameters ranging from 4 to 13 nm were prepared and characterized by transmission electron microscopy and SQUID magnetometry. Retention of the samples on the capillary was investigated as a function of solvent flow rate and the nanoparticle size and composition; the elution times of the nanoparticles are strongly dependent on their magnetic moments. We demonstrate the use of this method to separate a mixture of nanoparticles into size-monodisperse fractions. The magnetic moments of the particles are calculated based on analysis of the retention parameters and correlate with values obtained in separate SQUID magnetometry measurements.

Original languageEnglish (US)
Pages (from-to)5055-5062
Number of pages8
JournalAnalytical Chemistry
Issue number15
StatePublished - Aug 1 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry


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