Abstract: An apparatus and method for fractionating a liquid sample is disclosed. The liquid sample is generally blood plasma or blood serum from which it is desired to selectively remove low density lipoproteins while leaving behind high density lipoproteins. The apparatus comprises a chamber having a plurality of inert beads or particles in an upper portion thereof. The chamber is preferably defined by a disposable column. A dry reagent aliquot suitable for reacting with the liquid sample is coated upon the beads or particles. An upper filter is disposed in the chamber below the beads to retain the liquid sample during reaction. After reaction, the liquid sample is expressed through the upper filter and flows into a lower portion of the chamber. The lower portion includes a lower filter which separates low density lipoprotein containing flocculent from high density lipoprotein containing supernatant.