Forward suction

This approach is a routine laboratory operation method, suitable for low-viscosity, non-volatile and bubble-free liquids, such as pure water and ordinary buffers, and can ensure low error in pipetting in normal scenarios. The specific operation steps are as follows

First, select a pipette tip that matches the volume range of the pipette. Align the pipette vertically with the tip, apply a little force and rotate it slightly to ensure a tight fit between the tip and the pipette barrel. Make sure the seal is good to avoid air leakage that may affect the accuracy.

Press the pipette operation button with your thumb to the first stop point. You can clearly feel the resistance. At this time, the air inside the pipette tip is squeezed out. Keep the button pressed unchanged.

Immerse the pipette tip vertically into the liquid, with a depth of about 2 to 3 millimeters. Then, slowly release the button. The entire process should be controlled within 1 to 2 seconds to prevent the formation of bubbles due to excessive speed. After releasing, hold it for 1 to 2 seconds to allow the liquid to fully enter the pipette tip.

Lift the pipette vertically. If the outer wall of the tip is stained with liquid, gently press it against the inner wall of the original container and scrape it to remove the excess droplets.

Move to the receiving container, bring the pipette tip close to the inner wall of the container at an Angle of 30-45 degrees, slowly press the button to the first stop point, hold for 1-2 seconds to allow the liquid to flow out fully, and then continue to press the button to the second stop point to empty the remaining liquid in the pipette tip.

Finally, lift the pipette, release the button, press the tip ejection button to discard the tip, and complete one forward pipetting.

Reverse aspiration

This method is an advanced operation for special liquids, suitable for high-viscosity glycerol and protein solutions, volatile ethanol and chloroform, as well as solutions containing surfactants that are prone to generating bubbles, etc. It can reduce liquid loss and volume errors. The specific operation steps are as follows

The preparatory work is the same as that of forward pipetting, including installing the pipette tip and setting the volume of the pipetting liquid. If the viscosity of the liquid to be pipetted is high, the pipette tip can be immersed in the liquid to be pipetted 2-3 times for rinsing to improve the accuracy of pipetting.

After lifting the pipette, gently scrape off the excess liquid on the outer wall of the tip against the edge of the original container to avoid contamination or affecting the pipetting volume.

Move the pipette tip to the receiving container and keep it close to the inner wall of the container. Press the button steadily until the first stop point and maintain this position. At this time, the set volume of liquid has been discharged, and there will be some liquid remaining in the pipette tip, which does not need to be discharged.

After that, directly lift the pipette, release the button, and discard the tip with the residual liquid together, or put the residual liquid back into the original container. It cannot be used for subsequent pipetting operations.