Patent ID: 8322539

Claim:
A filter vial apparatus, comprising: a tubular vial having a closed bottom, an open top and a sidewall defining a cylindrical interior with a diameter D located along a longitudinal axis of the vial, the closed bottom having a protrusion extending toward the open top, the vial bottom and protrusion defining an annular recess about the vial's longitudinal axis of the vial with the protrusion at the center of the annular recess; a tubular plunger assembly having a longitudinal axis, including: a plunger with opposing top and bottom ends joined by a sidewall to define an fluid holding cavity in the plunger, the bottom end having an outer annular surface and an inner annular surface axially offset toward the top end from the outer annular surface, the inner annular surface generally orthogonal to the assembly longitudinal axis and joined to the first annular surface by a recess sidewall to form a recess that encircles the assembly's longitudinal axis, the second annular surface defining a recess opening that is in fluid communication with the fluid holding cavity of the plunger; an annular cap having inner and outer concentric sidewalls defining an annular recess into which the outer annular surface on the bottom of the plunger is placed, the cap's outer sidewall extending over the outer surface of the bottom of the plunger and the cap's inner sidewall being placed adjacent the sidewall of the recess in the end of the plunger, the inner sidewall of the cap defining a shaped cavity configured to snugly receive the protrusion on the vial's bottom, the shaped cavity having an upper end in fluid communication with the recess opening, an outer surface of the outer sidewall of the cap having a diameter sufficiently larger than diameter D to form a fluid tight seal when the plunger assembly is inserted into the vial yet allow movement of the annular cap to the bottom of the vial; a filter interposed between the inner annular surface in the plunger and the inner wall of the annular cap; wherein the annular cap on the bottom of the plunger assembly is configured to fit into the annular recess at the bottom of the vial.