Micropipette calibration is typically performed using the gravimetric method, where the volume dispensed is determined by measuring the weight of distilled water.
Step-by-Step Gravimetric Calibration
- Acclimate Equipment: Place the micropipette, distilled water, and tips in the calibration room for at least 2 hours to reach a stable temperature (ideally between 20°C and 25°C)
- Setup the Balance: Place a small, clean beaker containing 3 mm of distilled water onto an analytical balance and zero the scale.
- Pre-wet the Tip: Aspirate and dispense the target volume 3–5 times to humidify the air inside the tip and pipette.
- Weigh the Volume: : Aspirate the liquid, touch the tip to the inner wall of the beaker at a 45° angle, and dispense the full amount. Record the weight, re-zero the balance, and repeat this at least 10 times at both the minimum and maximum volumes of the pipette.
- Calculate Results: Convert the recorded weight (mg) to volume (μL) by dividing the weight by the density of water (Z-factor) at the recorded temperature.
