Asymmetric flow field flow fractionation

The asymmetric flow field - flow fractionation ( AF4/aFFFF, Eng. Asymmetric flow field -flow fractionation ), often referred to as "asymmetrical flow field flow ", is a young separation method for the fractionation and analysis of substances. It is a variation of the field-flow fractionation ( FFF).

The AF4 is in certain molecular weight ranges (about 1 10 kDa MDA) complementary to the size exclusion chromatography ( GPC / SEC). While at the SEC, the separation due to the molecular size- dependent interaction takes place with a porous stationary phase, at the FFF applied perpendicular to the flow direction field will be used. With the FFF, it is possible in addition to charged and uncharged polymers, aggregates, and proteins to analyze even viruses. Separations carried out in a range of about 1 nm to 100 microns.

The detection of the analyte is eluted by means of UV spectrometers, refractive index detector, and light scattering detectors. The coupling of AF4 with multi- angle laser light scattering ( MALLS ) allows the analysis of particle sizes without the use of size standards.

The advantage of the FFF to the SEC is its speed, the absence of shear forces and interactions to the stationary phase and the dynamic separation area. The separation is gentle and high-resolution. Analytes may be dissolved or dispersed.