SubscribeART®, self-sealing barrier tips from Molecular BioProducts, inc., were compared with filter tips from Continental Lab Products, Inc. (CLP), Oxford, LabCon and USA Scientific in a test designed to measure the degree of protection each tip provides against radioactive label (32PdCTP).
Abstract
Three randomly chosen, 20 µl pipette tips from each manufacturer were used to intentionally overdraw radioactive label and any liquid that passed beyond the anti-aerosol insert was tested on a scintillation counter.
Only ART tips completely blocked the passage of liquids and radioactive label. Of the five tips tested, only ART tips provided complete and consistent protection against pipettor contamination.
Introduction
Pipette tips with anti-aerosol inserts were specifically designed to prevent carryover contamination from liquids and aerosols that come in contact with the pipettor. For example, if liquid samples are accidentally overdrawn, contamination will spread to subsequent reactions through direct contact with the pipettor barrel.
Likewise, samples can be corrupted through the transmission of aerosols generated by the action of pipetting. The resulting contamination can lead to inaccurate results and illustrates the importance of an effective aerosol barrier.
Objective
Various aerosol-blocking technologies have been developed, each claiming to prevent carryover contamination. The subtle and seemingly insignificant differences between these technologies can mean the difference between success and failure in experiments that depend on the use of uncorrupted samples.
Therefore, this study was designed to test the true effectiveness of pipette tips from CLP, USA Scientific, Oxford, LabCon, and ART®, self-sealing barrier tips from Molecular BioProducts, inc.
Materials And Methods
In an independent lab, 20 µl samples of radioactive label (32PdCTP) were carefully drawn as test aliquots for pipette tips randomly chosen from each of the five manufacturers. All samples were counted on a scintillation counter to determine initial counts per minute.
Each tip was used on a 200 µl pipettor intentionally set at 200 µl to overdraw radioactive label through the inserts. Any liquid that passed beyond the inserts was collected with a 20 µl pipettor set at 20 µl.
The exact volume retrieved was then determined by backing down the pipettor volume adjustment until the fluid in the tip reached the point.
After the exact volume was recorded, the fluid was expelled and counted on a scintillation counter to determine counts per minute. This was compared to the initial cpm’s recorded at the beginning of the test to determine the percent penetration of radioactive label. The results for each tip were recorded and are summarized in the table below.
Results
| ART | 1 | 2 | 3 |
| Initial cpm | 1,537,180 | 1,537,180 | 1,537,180 |
| Filtered cpm | 152,190 | 0 | 0 |
| % Penetration | 9.90% | 0.00% | 0.00% |
| Volume Penetrated (ul) | 2.34 | 0 | 0 |
| CLP | 1 | 2 | 3 |
| Initial cpm | 393,870 | 393,870 | 393,870 |
| Filtered cpm | 314,850 | 120,950 | 162,570 |
| % Penetration | 79.94% | 30.71% | 41.28% |
| Volume Penetrated (ul) | 16.5 | 12.04 | 15.64 |
| Oxford | 1 | 2 | 3 |
| Initial cpm | 405,500 | 405,500 | 405,500 |
| Filtered cpm | 304,750 | 300,700 | 303,910 |
| % Penetration | 75.51% | 74.16% | 74.95% |
| Volume Penetrated (ul) | 16.52 | 16.3 | 15.6 |
| LabCon | 1 | 2 | 3 |
| Initial cpm | 1,523,360 | 1,523,360 | 1,523,360 |
| Filtered cpm | 1,209,310 | 115,120 | 69,913 |
| % Penetration | 79.38% | 7.56% | 4.59% |
| Volume Penetrated (ul) | 18.59 | 1.92 | 1.42 |
| USA | 1 | 2 | 3 |
| Initial cpm | 1,584,350 | 1,584,350 | 1,584,350 |
| Filtered cpm | 0 | 0 | 0 |
| % Penetration | 0.00% | 0.00% | 0.00% |
| Volume Penetrated (ul) | 0 | 0 | 0 |
As shown in the tables, only the ART, self-sealing barrier tips from Molecular BioProducts, inc., prevented radioactive label from passing to the pipettor. In every other case, sample with significant cpm levels passed through the filters freely, creating the opportunity for pipettor contamination.
The inconsistent densities of the filters becomes evident when using the viscous radioactive label. The USA and Oxford tips allowed a range of 4.59% to 79.38% penetration and 30.71% to 79.94% penetration respectively.
LabCon tips showed approximately 75% penetration in every tip tested. Although two of the three CLP tips were able to block the viscous liquid, the 33% failure rate is no guarantee of consistent protection from carryover contamination.
Preserving sample integrity is paramount to achieving accurate results in bioresearch, and aerosol-blocking pipette tips have been specifically designed for this purpose. Regardless of the source of potential contamination, choosing the right pipette tips is essential in guaranteeing protection against carryover contamination.
It is clear from this study that filter technology is not as effective as the self sealing barrier technology which is patented by Molecular BioProducts, inc. In test after test, ART tips are consistently proven to be the only pipette tip to offer a barrier that completely blocks liquids and aerosols.
Discussion
Preserving sample integrity is paramount to achieving accurate results in bio-research, and aerosol-blocking pipette tips have been specifically designed for this purpose. Regardless of the source of potential contamination, choosing the right pipette tips is essential in guaranteeing protection against carryover contamination.