Patent ID: 6077442
Filing Date: 2000-06-20
Classification: B01D,B01L,G01N

Abstract:
A method of pressing into a collection tube holding separated blood as a lower solids mass and an upper liquid mass defining with the lower mass an interface a filter comprising a sleeve fittable in the tube and having a lower end covered by a membrane that fits snugly in the tube, the method comprising the steps of:monitoring a vertical position of an upper surface of the upper liquid mass in the tube;engaging a pusher with an upper end of the sleeve and pushing the filter downward in the tube so as to force the liquid mass upward through the filter into the sleeve;stopping downward pushing of the filter when the upper end of the sleeve is at a predetermined spacing above the current vertical position of the liquid upper surface;is monitoring pressure exerted on the filter as it is pushed downward and thereby determining a vertical position of the interface; andstopping downward pushing of the filter when the membrane is at the vertical position of the interface.