To avoid contamination and ensure accurate and reliable results, pipette tips should be changed regularly. The frequency of tip changes depends on several factors, including the type of experiment, the sample being pipetted, and the level of cleanliness required. However, as a general guideline, here are some recommendations:
Disposable tips: If you are using disposable pipette tips made of plastic, it is recommended to use a new tip for each sample or reagent to prevent cross-contamination. This practice is particularly crucial when working with sensitive samples, such as DNA or RNA, where even trace amounts of contamination can affect the results.
Reusable tips: Some pipette systems have reusable tips that can be autoclaved or sterilized between uses. In this case, the tips should be cleaned and sterilized following the manufacturer's instructions. However, it is still important to regularly inspect the tips for wear, damage, or buildup that may affect their performance. If any issues are detected, the tips should be replaced promptly.
Regular intervals: Even when using disposable tips, it is advisable to change them periodically during long experiments or when working with large sample volumes. This practice helps maintain consistent accuracy and reduces the risk of contamination from accumulated aerosols, liquid carryover, or tip degradation.
Good laboratory practices: Aside from regular tip changes, it is essential to follow good laboratory practices to minimize contamination. This includes handling the tips with clean gloves, avoiding touching the inside of the tips, and using filter pipette tips when working with sensitive samples or volatile reagents.