Patent ID: 7790117

Claim:
A filter vial apparatus having a longitudinal axis, comprising: a tubular vial having a closed bottom, an open top and walls defining a cylindrical interior with a diameter D; a tubular piston with opposing distal and proximal ends with at least the distal end being open, the piston having walls defining a cylindrical interior with an exterior facing recessed portion adjacent the distal end the piston, the piston further having a distal piston flange at or adjacent to the distal end of the piston and extending outward from the piston; a filter support located inside the piston at the distal end of the piston; a retainer cup having a continuous sidewall extending between a proximal and distal end of the cup with an interior diameter smaller than the distal piston flange and having a lip extending inward toward the longitudinal axis at the distal end of the retainer cup, the retainer cup further having a cup seal extending outward from the proximal end of the cup a distance greater than the diameter D, the sidewall of the cup being sufficiently flexible to deform outward as the cup passes over the distal piston flange to assume an outer dimension larger than diameter D at the location of the piston flange when the retainer cup passes over the distal piston flange; and a filter interposed between the retaining cup's lip and the distal end of the piston when the proximal end of the retainer cup is placed over the distal end of the piston.