Modified syringe design prevents plunger-related contamination--results of contamination and flow-rate tests.

The usual mechanism for syringe contamination is spread of micro-organisms along the inside of the barrel. Two or more full strokes of the plunger will inevitably transport a contaminant from the inside wall into the sterile compartment. We modified syringes by replacing the plunger with a modified version that has an additional central O-ring seal.