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Meeting in Florida: Using Asymmetric Flow Field-Flow Fractionation (AF4) to Determine C60 Colloidal Size Distributions
Citation:
Isaacson, C., X. MA, B. Wigington, AND D. BOUCHARD. Meeting in Florida: Using Asymmetric Flow Field-Flow Fractionation (AF4) to Determine C60 Colloidal Size Distributions. Presented at SETAC 29th Annual Meeting, Tampa, FL, November 16 - 20, 2008.
Impact/Purpose:
The purpose of this investigation was to: develop an AF4 fractionation method for aqueous fullerene suspensions; explore how size range is affected by ionic strength and method of aggregate generation.
Description:
The study of nanomaterials in environmental systems requires robust and specific analytical methods. Analytical methods which discriminate based on particle size and molecular composition are not widely available. Asymmetric Flow Field-Flow Fractionation (AF4) is a separation technique which is able to separate particles from 1 nm to 10 µm in diameter based on differences in particle diffusion coefficients in aqueous media. AF4 is readily coupled to Dynamic Light Scattering (DLS) detectors for facile size determinations. AF4 fractions are also easily collected and analyzed by liquid chromatography mass spectrometry for molecular identification and quantification. When C60 aggregates were size-separated by AF4, the aggregates ranged in size from less than 40 nm to 450 nm (the filter cutoff) depending on the method of aggregate generation. The aggregate sizes were determined by dynamic light scattering and corroborated with electron microscopy. Fractions were also analyzed for apparent surface charge and mass concentration. As the size of the C60 aggregates increased the absolute value of their zeta potential decreased. Mass determination by LC-MS showed 50% of the mass of the C60 aggregates had diameters between 140 and 250 nm.