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Asymmetric Flow-Field Flow Fractionation (AF4) of Aqueous C60 Aggregates with Dynamic Light Scattering Size and LC-MS
Citation:
Isaacson, C. W., XIN MA, S. Lee, AND D. BOUCHARD. Asymmetric Flow-Field Flow Fractionation (AF4) of Aqueous C60 Aggregates with Dynamic Light Scattering Size and LC-MS. Presented at SETAC North America 30th Annual Meeting, New Orleans, LA, November 19 - 23, 2009.
Impact/Purpose:
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Description:
Current methods for the size determination of nanomaterials in aqueous suspension include dynamic or static light scattering and electron or atomic force microscopy techniques. Light scattering techniques are limited by poor resolution and the scattering intensity dependence on particle size. Microscopy techniques are limited by sample preparation artifacts and are cumbersome when multiple samples must be analyzed. Asymmetric flow-field flow fractionation (AF4) is an open channel size separation technique in which particles are separated by difference in diffusion coefficients. AF4 can operate under an array of solution conditions, including a large range of ionic strengths and surfactants. In addition, AF4 has the unique capability of separating particles ranging from 1 to 500 nm in hydrodynamic diameter (Dh). Presented herein is the first report of the size fractionation of aqueous C60 aggregates (aqu/C60) by AF4 coupled in line with dynamic light scattering (DLS) for size determination. Surfactants, which are commonly used to enhance particle stability, were avoided as they may alter particle size. Additionally, to determine the mass of C60 in each size range, fractions were collected from the AF4 and the amounts of C60 were quantified using LC-APPI-MS. As determined by DLS aqu/C60 ranged in size from 80-260 nm in Dh which was verified by the analysis of fractions by DLS in batch mode as well as by TEM. Of the total mass of aqua/C60, 7.7 ± 6.9 % of the aqua/C60 mass had Dh less than 80 nm, while 58 ± 32 % had Dh between 80-150 nm and 14 ± 9.2 % of the aqua/C60 were between 150-260 nm in Dh. Deposition was observed in the AF4 channel as 79 ± 5.7 % of the initial aqua/C60 eluted from the AF4 channel. The use of membranes with hydrophobic and hydrophilic functionalities did not reduce the amount of aqu/C60 deposited. As predicted by AF4 theory, detector flow splitting increased the detector response, although increasing the split ratio beyond 80% of the channel flow resulted in elution of aqu/C60 in the split flow stream.
URLs/Downloads:
BOUCHARD 09 077A SETAC 11.09.09 NEW ORLEANS.PDF (PDF, NA pp, 770 KB, about PDF)BOUCHARD 09 077 SETAC NEW_ORLEANS.PDF (PDF, NA pp, 11 KB, about PDF)