Avoiding contamination with plastic pipette tips

[HW Mueller]

Interesting Bruce! One thing though, in work with syringes with plain metal pistons (5 to 500µL HPLC syringes) I found that you have to remove the piston, wash it, flush the syringe with washing solvent (drawing it through with vacuum), drying this way with air, reassembling (~ 30sec). Otherwise I had carryover or other contamination quite often.

[Bruce Hamilton]

One thing though, in work with syringes with plain metal pistons (5 to 500µL HPLC syringes) I found that you have to remove the piston, wash it, flush the syringe with washing solvent (drawing it through with vacuum), drying this way with air, reassembling (~ 30sec). Otherwise I had carryover or other contamination quite often.

Yes. That's why I use the Gas Tight series. They have an expanded PTFE seal at the front of the plunger that works for both aqueous and organic solvents. I'm familar with SGE, but I think other manufacturers offer the same, and most dilutors/dispensors use similar PTFE plunger seals.

The standard metal plunger-in-barrel syringes allow solvents between the plunger and barrel, and that's very difficult to remove by flushing. For the Gas Tight series with removable needle, when you do need to dismantle and clean them, it's easy,

Bruce Hamilton