Reuse disposable filter elements

This is the most fundamental misunderstanding. The aerosols, impurities and microorganisms adsorbed by disposable filter elements will remain in the pores of the filter material. When reused, these pollutants will fall off, causing serious cross-contamination instead. Repeated suction and discharge of liquid simultaneously will damage the structural sealing of the filter element, resulting in a sudden drop in filtration efficiency. The correct approach: Regardless of whether the experimental sample is "clean" or not, the filter cartridge should be discarded immediately after a single use along with the pipette tip.

Ignore the compatibility of the filter element with the pipette tip/pipette

Blindly choosing filter elements that do not match the size (such as installing small-volume filter elements in large-diameter suction heads) will lead to poor sealing, with air leakage through the gaps, completely losing the filtering effect. It may also lead to inaccurate pipetting volume and liquid reflux during pipetting. The correct approach: Give priority to choosing pre-installed filter cartridge pipette tips that match the pipette tip brand and specification (10μL/200μL/1000μL). If an independent filter element is used, it is necessary to confirm that the outer diameter of the filter element is closely attached to the inner wall of the pipette tip.

Incorrect high-temperature sterilization operation

Some experimenters will subjecting ordinary PP material filter elements to high-pressure steam sterilization, believing that it can enhance sterility. However, the upper temperature resistance limit of PP filter elements is approximately 121℃. Frequent sterilization will cause the filter material to deform, the pores to collapse, and lose its filtering function. Moreover, filter elements in non-sterile packaging may also introduce new contamination after sterilization. The correct approach: For cell culture and aseptic experiments, directly purchase pre-installed filter cartridge pipette tips sterilized by irradiation. If sterilization is indeed necessary, only select the dedicated filter element marked "can be sterilized under high pressure", and the sterilization frequency should not exceed one time.

Confuse the compatibility of the filter element material with the sample

When treating organic solvents (such as methanol, acetone) or strong acid and alkali solutions with ordinary PP filter elements, the PP material will be corroded and dissolved. Once the filter element fails, contaminants will directly enter the pipette. Conversely, when treating aqueous phase samples with PTFE filter elements, excessive hydrophobicity will lead to excessive liquid absorption resistance. The correct approach: Select the material based on the sample type - for aqueous phase/conventional acid and alkali, choose PP. For organic solvents and highly corrosive samples, choose PTFE. For trace and precious samples, choose low-adsorption PE.

Over-reliance on filter elements while neglecting the daily maintenance of pipettes

It is believed that once a filter element is installed, there is no need to clean the pipette. If it is not disassembled and maintained for a long time, the contaminants intercepted by the filter element will accumulate at the interface of the pipette tip, breeding microorganisms. It may even indirectly affect the sealing effect of the filter element due to the wear of the piston and the aging of the sealing ring. The correct approach: Regularly disassemble the pipette's tip cone, piston and other components, and wipe them clean with a dedicated cleaner. Clean up the residual liquid at the pipette tip interface in time after the experiment.