Pipette tip container

A pipette tip container comprising:

• a pipette tip having a lumen extending between a proximal opening of a first diameter and a distal orifice of a second diameter smaller than the first diameter;
• at least one pellet of material arranged in the lumen of the pipette tip between said proximal opening and distal orifice, wherein the second diameter is too narrow to let the pellet pass;
• and
• a retainer arranged in the lumen between the pellet and said proximal opening, the retainer being arranged to prevent the at least one pellet from moving past the retainer in the lumen but to let fluid move past the retainer in the lumen;
• the retainer having a distal end and a proximal end, wherein the distal end of the retainer is circumscribed within a third diameter and the proximal end of the retainer is circumscribed within a fourth diameter, which is larger than the third diameter, wherein at least a first portion of a periphery of the distal end of the retainer does not contact an inner wall of the lumen and wherein at least a portion of a periphery of the proximal end of the retainer exerts resilient pressure on the inner wall of the lumen and maintains the retainer in the lumen by friction with the inner wall of the lumen.