I. Core Issue: The accuracy of the volume of the transferred liquid is seriously deviated, which directly affects the experimental data

The matching degree between the pipette tip and the pipette is the key to ensuring that "the set volume = the actual pipette volume". Poor matching can lead to "insufficient pipetting" or "residual pipetting", which is specifically manifested as

The suction volume is insufficient, and the actual volume is far lower than the set value. If the inner wall of the pipette tip does not fit tightly with the cone of the pipette tip (such as when the tip diameter is too large or there is a gap in the cone), "air leakage" will occur during suction - the negative pressure inside the pipette cannot fully act on the liquid, and some air enters through the gap, resulting in the actual suction volume being less than the set value (the deviation can reach 5%-20%) Or even more. For instance, if 100μL of liquid is set to be transferred, only 85μL is actually drawn in due to a leak in the pipette tip. If this is used for "adding primers or templates" in a PCR reaction, it will lead to insufficient concentration in the reaction system, resulting in "amplification failure" or "abnormal band brightness".

Excessive residue during pipette discharge and incomplete release of liquid: Poorly matched pipette tips (such as overly soft material, rough inner walls, or overly tight contact with the cone of the pipette, resulting in an increase in "dead volume") can cause liquid to remain on the inner walls or bottom of the pipette tip during discharge and cannot be completely pushed out. For instance, when transferring viscous liquids (such as serum or enzyme solutions), inferior pipette tips may leave 10% to 15% of the liquid residue. If used for "standard curve preparation", it will cause the actual concentration at each concentration point to be lower than the theoretical value, deteriorate the linearity of the standard curve, and ultimately affect the accuracy of the sample quantification results.

The repeatability of pipetting is poor, and the data of parallel experiments fluctuate greatly. Even if the same volume is set each time, poorly matched pipette tips will cause "unstable leakage degree" (such as different fit between the pipette tip and the cone each time), resulting in significant differences in the volume of liquid pipetted each time. For instance, if three parallel pipetting operations are conducted (with 50μL set), the actual volumes might be 48μL, 52μL, and 46μL respectively. The relative standard deviation (RSD) exceeds 5% (RSD should be ≤1% under normal matching). Such fluctuations would render the experimental data statistically insignificant and prevent reliable conclusions from being drawn.

Ii. Derivative Issues: Cross-contamination of samples leads to misjudgment of experimental results

Poor matching of pipette tips and pipettes not only affects accuracy but may also disrupt "sample isolation" and cause cross-contamination, which is particularly dangerous in molecular biology and microbiological experiments.

Aerosol contamination: Leakage of the pipette tip causes the liquid to atomize and diffuse. If there are gaps during pipetting, the airflow inside the pipette will "atomize" the liquid into tiny aerosols. These aerosols may enter the interior of the pipette through the gaps (such as the cone of the pipette tip or the piston cavity), contaminating the pipette body. When using a new pipette tip to transfer other samples for the next time, the residual aerosol will enter the new sample with the airflow, causing "cross-contamination". For instance, when a sample containing the novel coronavirus is first taken, an aerosol may contaminate the pipette due to a leak in the pipette tip. When a negative sample is later taken, the negative sample will be contaminated by the virus in the aerosol, resulting in a "false positive" test result.

The detachment of the pipette tip can cause liquid leakage and contamination. Some pipette tips do not match the "locking structure" of the pipette (such as the size of the pipette tip clamp not fitting the cone of the pipette). During the pipetting process (especially when rapidly aspirating or discharging liquid or moving vertically), the pipette tip may suddenly fall off, causing the liquid inside the tip to directly spill onto the laboratory bench, other sample tubes or instruments, resulting in "direct contamination". For instance, when removing the bacterial liquid containing Escherichia coli, the pipette tip may fall off, causing the bacterial liquid to spill onto the PCR tube. If not cleaned in time, the PCR reaction will be contaminated by bacteria, resulting in "non-specific amplification".