N.50 – Ten suggestions to apply the Best Micro-Pipette Practice in microbiology

TRIO

  1. Equipment Care – Service every 8-12 months (Calibration, greasing parts, seals replacement, cleaning, disinfection, etc.).
  2. Tips – Replace tips every transfer (reused tips will carry extra organisms over the next sample).
  3. Aspiration Depth – Place tip just below the surface of the liquid (Too deep results in extra organism carry over on the outside of the tip).
  4. Slow, fluid motions – Do not allow pipette to “snap” up liquid into the tip (This creates air bubbles in the tip, and risk liquid entering the pipette shaft).
  5. Contamination Protection – Use filter tips! Sanitize before and after each use, or even between organisms! Never lay micro-pipette down with liquid in the tip because liquid can travel up the pipette shaft!
  6. Pipette Angle – Aspirate at vertical 90° angle and dispense at 45° angle. These angles ensure the liquid enters and exit the tip properly for the best accuracy.
  7. Touch-off – When dispensing give the tip a final touch off  on the edge of the receptacle! Water tension can prevent the full volume from leaving the tip – even after blowout.
  8. Temperature matters – Equilibrate your micro-pipette to room temperature before use! Hold your micro-pipette only when actively pipetting; heat can transfer from your hand! Micropipettes are most accurate when liquid, pipette and air temperature are as similar as possible.
  9. Pre-Wet – Fully pre-wet each tip prior to extracting your sample! Volume will not cling to the dry sides of the tip interior after pre-wetting!
  10. Most appropriate micro-pipette for Volume – Use the micro-pipette with the most narrow range that includes your desired volume! Accuracy decreases as you approach the minimum value of the instrument!