1.Poor sealing accuracy → Air leakage, significant volume deviation

The pipette relies on the negative pressure of the piston to draw liquid. If the connection between the pipette tip and the gun handle is not tight and there are gaps at the interface, air leakage will occur:

When drawing liquid, air bubbles are sucked in, and the actual volume of the liquid is much lower than the set value;

When discharging the liquid, it is impossible to completely push out the liquid;

When making standard curves, enzyme labeling, and PCR reaction systems, the concentration ratio is directly incorrect, causing curve drift and abnormal PCR amplification. 

2. Insufficient smoothness of inner wall / Insufficient hydrophilicity/hydrophobicity → Liquid adheres and remains on the wall 

The inner wall of the inferior suction head is rough and the material has uneven hydrophobicity/hydrophilicity: 

After suctioning, there is residual liquid adhering to the inner wall of the tube, which cannot be completely drained. 

When transferring a small amount of liquid (in the μL range), the residual error is multiplied by several times. 

When conducting enzyme reactions, fluorescence quantification, and micro-dilution, the differences between groups become larger, making it impossible to obtain repeatable data. 

3. Inconsistent appearance dimensions → Each suction head has different errors 

There are significant deviations in the length, diameter and taper of the same batch of suction heads. 

Each time a new suction head is used, the dead volume and the depth of immersion in the liquid surface both change. 

The same person, the same pipette, and the same set volume, but the results of multiple pipetting operations vary greatly. 

The experimental repeatability was poor and there were failures in the parallel samples. It was impossible to rule out systematic errors other than those caused by the operation.