Effect of inlet frit lengths on the hydrodynamic relaxation efficiency in frit inlet asymmetrical flow field-flow fractionation

The efficiency of a frit inlet asymmetrical flow field-flow fractionation (FI-AFlFFF) channel has been evaluated by varying the length of the inlet frit element. In a FI-AFlFFF channel, a high speed frit flow is introduced through the inlet frit to provide hydrodynamic relaxation of the incoming sample stream from the channel inlet. The experimental plate heights and peak recovery values are examined for three different FI-AFlFFF channels by varying field strengths and the channel membrane materials. It has been found that the length of the inlet frit element influences the performance of hydrodynamic relaxation, as well as peak recovery in the FI-AFlFFF channel system. Experimental plate height data show that the hydrodynamic relaxation itself occurs more efficiently when the length of inlet frit is longer. While an FI-AFlFFF channel having a longer inlet frit (4.2 cm long) gives a good relaxation, it shows less efficiency in considering peak recovery over a range of the field strengths examined in this study. A similar tendency is observed when channel membrane is varied. By considering the efficiency of hydrodynamic relaxation and sample recovery during elution, an FI-AFlFFF channel of an intermediate length of inlet frit (3.2 cm) is shown, from experiments, to be optimum.