Do Filtered Pipette Tips Really Prevent Cross-Contamination and Aerosols?

In a laboratory, tough decisions are regularly made to determine how best to conduct critical experiments and testing. Over time, pipette tips have adapted to suit labs across the globe and provide the tools so technicians and scientists have the ability to do important research. This is especially true as COVID-19 continues to spread throughout the United States. Epidemiologists and virologists are working around the clock to come up with a treatment for the virus. Filtered pipette tips made of plastics are used to study the virus and the once bulky, glass pipettes now are sleek and automated. A total of 10 plastic pipette tips are used to perform a single COVID-19 test currently and most of the tips that are used now have a filter in them that is supposed to block out 100% of aerosols and prevent cross contamination when sampling. But how much are these significantly more expensive and environmentally costly tips really benefiting labs across the country? Should labs decide to ditch the filter? 

 

Depending on the experiment or test at hand, laboratories and research centers will choose to use either non-filtered or filtered pipette tips. Most labs use filtered tips because they believe the filters will prevent all aerosols from contaminating the sample. Filters are commonly seen as cost-efficient way to completely eliminate traces of contaminants from a sample, but unfortunately this is not the case. Polyethylene pipette tip filters do not prevent contamination, but instead only slows the spread of contaminants 

 

A recent Biotix article states, “[the word] barrier is a bit of a misnomer for some of these tips. Only certain high-end tips provide a true sealing barrier. Most filters only slow the liquid from entering the pipette barrel.” Independent studies have been done looking at alternatives to tip filters and their effectiveness compared with non-filter tips. An article published in the Journal of Applied Microbiology, London (1999) studied the effectiveness of polyethylene filter tips when inserted into the end of the pipette tip cone opening compared to non-filtered tips. Out of 2620 tests, 20% of samples showed carryover contamination on the pipettor nose when no filter was used, and 14% of samples were cross-contaminated when a polyethylene (PE) filter tip was used (Figure 2). The study also found that when a radioactive liquid or plasmid DNA was pipetted using no filter, contamination of the pipettor barrel occurred within 100 pipettings. This shows that although the filtered tips do decrease the amount of cross-contamination from one pipette tip to another, the filters do not stop contamination completely. 

 

 

Additionally, a 96-count rack of filtered tips costs on average about 35% more than a rack of unfiltered pipette tips, with an increase in average price of $3.85 per rack. This might not seem like much at first sight, but the amount of pipette tips used per year makes cost savings add up. For example, Rockefeller Labs purchased 16,500 boxes of tips in 2019 alone, making the difference between purchasing filtered or unfiltered tips reach $2.1 million.  

 

 

When considering whether to use filtered or unfiltered pipette tips in a laboratory, skilled technicians and scientists should weigh the benefits of filtered pipette tips and decide if they are worth the increased cost. The positive aspects of using unfiltered pipette tips give labs one more reason to consider reusing, cleaning, and sterilizing non-filtered tips with Grenova’s products as shortages occur due to the increase in COVID-19 testing ahead.  

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