Design of an asymmetrical flow field-flow fractionation channel for uniform channel flow velocity

A new design for an asymmetrical flow field-flow fractionation (FFF) channel, having a breadth that decreases exponentially along its length, is presented. It is shown that such a channel may be operated under certain flow conditions to obtain a constant mean channel flow velocity throughout its effective length. This is not possible with trapezoidal channels, which were themselves introduced with the objective of reducing the variation of mean flow velocities along the channel length. It is also shown that when operated under other flow conditions, the resulting variation in mean flow velocity is reduced in comparison to that predicted for trapezoidal channels. (C) 1997 John Wiley & Sons, Inc.