Pipette Tips

Pipette tips are cone-shaped, hollow plastic objects that fit on the end of a pipette to cleanly aspirate (suck in) and dispense small volumes of liquid. Together with a pipette, pipette tips create an air-tight seal so scientists can transfer accurate volumes of liquid from one vessel to another. Commonly made from polypropylene, they are made for one-time use and are available in various formats and volumes to fit specific applications and pipettes.

Because they come in direct contact with the sample of interest, pipette tips can significantly affect the results of an experiment. Discarding pipette tips between each experimental step helps prevent cross-contamination.

Pipette tip sterility refers to the absence of bacteria or any living microorganisms or spore, but without an additional qualifier (such as BioClean Ultra) can still contain contaminants that can have an influence on the outcome of an experiment. Reaction conditions and experimental results can be compromised by organic and non-organic contaminants unknowingly introduced to liquid samples by non-certified pipette tips. Contaminants can inflict adverse, unpredictable effects on enzyme activity and longevity, molecular interaction, spectrophotometric and chromatographic analysis, and more.

BioClean refers to the exceptionally high standard to which all Rainin air-displacement tips are tested and found to be free of detectable amounts of specific biological contaminants, such as DNA (human and bacterial), RNase, DNase, endotoxin, protein, protease, ATP and PCR inhibitors.

BioClean Ultra pipette tips are manufactured in a fully automated class 100,000 clean room facility. To assure absolute purity, no additives or dyes are used, and ISO 9001-compliant manufacturing procedures are followed to eliminate all external sources of contamination. From raw material selection to clean production and automated packaging, Rainin BioClean Ultra pipette tips are pure and completely safe.

Capillary and piston pipette tips, also known as syringe tips, fit on positive displacement pipettes. Compared to air-displacement pipettes – which are much more common – positive-displacement pipettes and tips are recommended for handling viscous, dense or other liquids that are physically difficult to move into and out of a pipette.

Why? Because air inside air-displacement pipettes can stretch and compress, which can cause measurement inaccuracies when working with a thick liquid. Capillary and piston pipette tips are filled by the piston, which extends down to the opening of the tip, virtually removing air between liquid and the end of the piston. With no air inside, capillary and piston syringe tips deliver excellent accuracy, reproducibility and control with viscous liquids. They are also recommended when pipetting volatile organic liquids and liquids with low surface tensions.

Pipette tips come in an assortment of sizes to help accommodate the needs of the user. The smallest volume pipette tip for general laboratory use is 10 microliters, while the largest is 20 milliliters. Pipette tips are tapered conical vessels, generally made from polypropylene, whose internal volumes are calibrated to aspirate, hold and transfer different liquid volumes during various analytical procedures.

Rainin LTS sizes and filter options: 20 µL filtered and unfiltered, 250 unfiltered/200 µL filtered, 300 µL filtered and unfiltered, 1000 µL filtered and unfiltered and 1200 µL filtered and unfiltered.

Rainin UNV (universal-fit) pipette tips sizes and filter options: 10 µL filtered and unfiltered, 20 µL filtered, 100 µL filtered, 250 unfiltered/200 µL filtered, 300 µL filtered and unfiltered and 1000 µL filtered and unfiltered.

Changing a pipette tip is dictated by the individual assay. To help eliminate the risk of cross-contamination, a fresh tip should be used after every aspiration/dispense cycle.

No, washing and reusing a pipette tip is not recommended. Tip surface properties change after wetting, particularly with organic liquids or liquids of diverse compositions. This alters liquid retention and hence, pipetting accuracy and precision. Also, organic liquids or constituents can diffuse into the polypropylene surface and contaminate subsequent liquids brought into the interior of the tip.  

In general, use a new tip for each sample, especially when working with sensitive, reactive or biohazardous materials. Even when using similar reagents, fresh tips ensure the highest level of purity and accuracy. This practice protects your results from carryover and contamination. Cost-effective, high-quality Rainin tips are designed to fit quickly and securely on Rainin pipettes, so you can change tips frequently without slowing your workflow or compromising data integrity.

For more pipetting technique tips, visit the good pipetting practice homepage.