Theoretical and experimental investigation of the focusing position in asymmetrical flow field-flow fractionation (AF4)

摘要

To better understand the focusing process and to determine the focusing position (z(foc)) in Asymmetrical Flow Field-Flow Fractionation (AF4), theoretical and experimental studies were performed. A new theoretical expression that allows the calculation of z(foc) in AF4 channels of any shape having an axial plane of symmetry was established. The equation was then applied to the particular case of a trapezoidal AF4 channel with tapered ends. The applicability of this equation was verified by comparing the calculated results with the experimental measures of the focusing position obtained using blue dextran dye under different flow conditions. The calculated values and the experimental results were in good agreement. The total uncertainty associated with the calculated z(foc) was evaluated and was lower than 10%. A good repeatability and reproducibility of the focusing position was obtained.