Asymmetric Field Flow Fractionation with different detectors (MALS, DLS, UV-vis). Nanoparticle separation by sizes

Dispersed-phases characterisation (Structural & Morphology Characterization)

In this instrument, a thin, flat channel is sandwiched between two walls, one of which is solid and the other which is made from a membrane through which water can be pumped. When a liquid containing different sizes of nanoparticles passes through the channel, careful control of the liquid flows along the channel and across the membrane can be used to separate the particles depending on their size, usually with smaller particles exiting the channel first. Size measurement of the separated fractions using on-line coupled DLS or MALS detectors allows a more precise determination of particle size compared to batch mode light scattering based methods by avoiding the misleading effect of strongly scattering, large particles. The typical working range is <500 nm (steric elution range, where larger particles start to travel faster and elute first from the column). The instrument usually performs well for negatively charged and PEG coated nanoparticles or in the presence of detergents or stabilisers that help to minimise the interaction with the semi-permeable membrane wall of the channel. Fraction collector allows the analysis of separated size fractions by methods like TEM that are not compatible with direct on-line coupling

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