Pipettes are indispensable precision tools in the laboratory, and the choice of their pipetting method is crucial to the accuracy and reliability of experiments. Among the many liquid aspiration methods, reverse liquid aspiration and forward liquid aspiration are two common operating modes, each with unique characteristics and applicable scenarios. The significant differences in the operation process, liquid adaptability and pipetting accuracy between these two methods of pipetting not only affect the efficiency and accuracy of the experiment, but are also directly related to the reliability and repeatability of the experimental results.

1. Operation process 1. Forward aspiration (1) First, immerse the pipette tip into the liquid. (2) Press the pipette button to the first position and slowly release the button to aspirate. At this time, a certain volume of liquid will be sucked into the suction head. (3) After the aspiration is completed, move the suction head above the target container. (4) Press the button again to the first position, and most of the liquid will be discharged. (5) Finally, fully press the button to the second position to blow out the remaining liquid in the tip. 2. Reverse pipetting (1) Similarly, first immerse the pipette tip into the liquid. (2) But at this time, you need to directly press the button to the second position and then release it to aspirate. Doing this will draw in more liquid to compensate for surface adsorption inside the tip. (3) After the aspiration is completed, move the suction head above the target container. (4) Press the button to the first position to drain the fluid. This method may leave a small amount of liquid residue because more liquid is sucked in initially. (5) Finally, additional operations are required to remove these residual liquids.

2. Applicable liquid types 1. Forward suction (1) Suitable for liquids with good fluidity and low foaming such as aqueous solutions. (2) In this kind of liquid, forward suction can ensure accurate transfer of liquid and avoid errors caused by bubbles or excessive liquid viscosity. 2. Reverse liquid suction (1) is suitable for viscous liquids, liquids that easily foam, or liquids that require precise measurement. (2) Reverse pipetting improves pipetting accuracy by sucking in more liquid to compensate for the surface adsorption inside the tip. At the same time, for liquids that are prone to foaming, reverse suction can reduce the generation of bubbles and ensure stable transfer of liquids.

3. Pipetting accuracy 1. Forward pipetting (1) If the operation is correct and the liquid type is appropriate, forward pipetting can provide relatively accurate pipetting results. (2) However, for some viscous or foaming liquids, forward aspiration may cause errors due to the liquid adhering to the inner wall of the tip or the generation of bubbles. 2. Reverse aspiration (1) Reverse aspiration improves pipetting accuracy by compensating for surface adsorption inside the tip. (2) Especially suitable for occasions requiring precise measurement, such as trace drug preparation, biological experiments, etc.

There are significant differences between reverse aspiration and forward aspiration of pipettes in terms of operation process, applicable liquid type, and pipetting accuracy. In practical applications, the appropriate liquid aspiration method should be selected according to the properties of the liquid and experimental requirements to ensure the accuracy and reliability of the experiment.

Related reading recommendations

Full-automatic pipetting workstation instruction manual

COVID-19 testing with Opentrons

OT-2 liquid handling robot safety and regulatory compliance information

Magnetic bead extraction and purification technology

Shenzhen Hechuang Bioengineering Co., Ltd.

Characteristics and functions of 20μl pipette tips