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.