Testing for particulates

Apparatus comprising:

• a tube having a proximal opening;
• a plunger sized and shaped to be inserted into the tube via the proximal opening and advanceable within the tube while sealably contacting the tube, a distal end of the plunger shaped to define one or more first passageways therethrough, wherein the plunger is shaped to define one or more compartments in fluid communication with the first passageways;
• and
• a filter coupled to the distal end of the plunger,
• wherein the plunger is shaped to define a second passageway that passes through the plunger from a proximal end of the plunger to the distal end of the plunger, in order to provide access to the filter, wherein the second passageway does not pass through any of the first passageways, and
• wherein the apparatus is configured such that while the plunger is advanced within the tube while fluid is within the tube, the fluid in the tube is pushed through the filter, through the first passageways, and into the one or more compartments.