Why Use Low Retention Pipette Tips
When pipetting liquids especially those with low surface tension, such as detergents, a film of solution often remains on the inner surface of ordinary polypropylene pipette tips. As a result, the accuracy and precision of the pipetting operation is reduced, and this can in some circumstances represent an important source of error during the experimental procedure.
These errors especially effect sensitive quantitative analysis methods such as those using ultra-low volume sample techniques and some molecular biology analyses.
Low retention pipette tips are now increasingly popular, their inner surfaces are hydrophobic and therefore prevent sample loss due to adhesion to the inner surface of the pipette tip. They are especially recommended for pipetting viscous liquids, for conserving rare or very expensive reagents, and for improving the accuracy and the reproducibility of experiments.
Low retention pipette tips are however more expensive so most labs only use them when there is a clear advantage, for example when using very expensive reagents or when variation between replicates and increased reliability of the assay can be improved by using the low retention tips.
Choosing a supplier
Low retention pipette tips can be manufactured by different techniques:
- using a controlled rheology polypropylene obtained from Ziegler-Natta copolymer and a peroxide
- Silicon treatment of pipette tips, which has the disadvantage of potential leaching or reacting with the reagents
- New polymer development, in order to obtain very smooth surfaces by innovative resin technologies
- The coating with fluoropolymers, which can affect the pipetting accuracy if it is unevenly distributed on the inner surface of the tip
- Hydrophobic surface and wide orifice, which can be used for microbiology tests and for pipetting viscous liquids
- Integration of fluoropolymers into the entire polypropylene matrix and the exposure of trifluoromethyl on the inner surface for avoiding the disadvantages of coating
There are various types of low retention pipette tips on the market, and the following factors should be considered when choosing the best low retention pipette tip to use:
- Orifice size – should be appropriate for the type of liquid that will be pipetted. Wide orifice pipette tips for viscous liquids and mammalian cells, and smaller orifices pipettes for when pipetting into narrow tubes.
- Sample retention – can be tested by pipetting a dye. The evaluation can be performed visually or, very precisely, by spectrophotometry. Gravimetric methods can also be used for testing the sample retention of the pipette tips.
- Manufacturer recommendations – very useful because the tip materials can sometimes interfere with some analysis methods (e.g., the molecular biology analyses) or can be affected by sterilization procedures or by certain chemical solutions. Certain procedures require pipette tips that are free of nucleic acids, enzymes, inhibitors, metals, etc.
Low retention tips are recommended for various application, such as:
- Molecular biology techniques, including PCR, nucleic acid sequencing, gel electrophoresis, or blotting, methods that require the addition of very small amounts of reagents that sometimes contain detergents or are very expensive
- Ultralow-volume spectroscopy, which requires a minimum amount of sample
- Proteomics and genomics techniques, involving very small amounts of proteins or nucleic acids
- Pipetting cultured cell suspensions that can be damaged easily, an operation that requires the use of the wide orifice low retention pipettes
- Pipetting viscous liquids or solutions with low surface tension
- Pipetting very rare or expensive reagents
More Guides:Select a Liquid Handling Guide:
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