RAPID SEPARATION OF MICRON-SIZED PARTICLES BY FIELD-FLOW FRACTIONATION USING EARTHS GRAVITATIONAL-FIELD

This paper presents the rapid separation of latex particles of diamete rs 5-20 mum in a simple arrangement of the separation channel. Lift fo rces, which play an important role in the process, drive particles ver y quickly from the channel bottom, and they cause a decrease in retent ion times at first and then a deterioration of resolution when the flo w rate increases. The magnitude of the lift forces depends on the flow rate and particle size among others. Several published observations c oncerning the lift forces are mentioned, and several suggested formula s for these forces are presented. Our experimental data are compared t o the lift forces function which seems to be the most relevant: the fu nction suggested by Vasseur and Cox and simplified by Kononenko and Sh imkus that originates in inertial effects of the flow. The consequence s of such a separation mechanism are discussed with respect to the lim itations and advantages of lift forces activity.