Pipettes and pipette tips are used to transfer and measure specific volumes of liquids in many laboratories. Pipettes have mechanical precision in their structure and the pipette tip also has the same significance because it is the part of the pipette that comes into contact with the sample. Choosing wrong tips leads to inaccuracy, contamination or loss of sample where a high degree of precision is required in experiments.
Pipette tips are of different types and there are special pipette tips to overcome some of the difficulties such as highly viscous liquids, small volumes of liquids and toxic liquids. It is thus very important to use the right speciality pipette tip so that the best results may be obtained.
There are pipette tips that are developed to suit certain difficulties that could be experienced in the laboratory.
Here are some of the most frequently used speciality tips and the projects for which they are most suitable:
Low-retention pipette tips are those tips that are specially made in such a way that the liquid will not adhere to the inner walls of the tip. For instance, it is usual that they use a hydrophobic surface coating to minimize the amount of the left liquid and to obtain the sample nearly in its totality. This kind of tip is especially helpful for:
There is a seal on filter pipette tips that shall help greatly in reducing the amount of aerosols and liquid that comes in contact with the pipette barrel. This makes them suitable to be used in handling hazardous or poisonous substances in the workplace. Common uses for filter tips include:
Large-bore pipette tips are made with a larger hole for the samples that can shear or clump easily such as cells, DNA or proteins. These tips reduce mechanical stress on the sample. Applications include:
Gel-loading tips are long and thin tips that are specifically used to load samples in the gel for the process of electrophoresis. These tips have a small diameter that allows the samples to be adequately pipetted into the wells of agarose or polyacrylamide gels. Key applications include:
These pipette tips are slightly longer than the normal ones; they are used especially in deep vessels including 15 mL or 50 mL centrifuge tubes. These tips do not contaminate the sample in that the pipette tip does not touch the walls of the tube. Common applications include:
Some points have to be taken into consideration to choose the proper speciality pipette tip for an application. The following are some aspects that may be useful in making the decision.
Sample Type
It is therefore important to understand that the nature of the liquid or the sample that you are dealing with defines the kind of tip to be used. When the samples are viscous or tacky in some way then low-retention tips are ideal for use. For delicate cell suspension, the wide-bore tips ensure that cells are not damaged during the pipetting process.
Volume Requirements
Sample size also dictates the type of tips to be used in a study. For low-volume pipetting for instance in molecular biology or genomics, the tips used must have low carryover. For large volumes, that is, when moving large volumes of media or other solutions in cell culture, the normal tips such as the standard or the extended length tips are ideal.
Risk of Contamination
For example, if there is cross-contamination in PCR or cell culture the filter tips come in handy. They reduce the amount of aerosols that come onto the pipette and ensure the samples’ cleanliness.
For you to be able to get the best out of your specialty pipette tips, you have to be very careful about how you handle the liquids. Below are some tips that will help you enhance your technique and achieve the right results:
Pre-Wet the Tip
The last sample should be aspirated with the pipette tip pre-wet at least one or two times before the samples are taken. This eliminates evaporation within the tip and ensures accurate transfer of quantity from one well to another.
Work at a Consistent Rate
Make sure that the rates at which aspirating and dispensing of fluids should be equal. These are very delicate processes and cannot be performed at high velocities since this will create the formation of bubbles and splashes which will lead to erroneous measurements and loss of samples.
Hold the Pipette Vertically
When pipetting liquids it is recommended that the pipette be held in a vertical position to ensure that the correct volume has been drawn into the pipette tip. Another way is that the movement of the pipette can also create some level of inaccuracy in the measurement and therefore precision is affected.
Speciality pipette tips are especially advantageous in a range of particular laboratory applications. Whether it is DNA samples or cell cultures, chemicals that are hazardous to the environment or human beings, there is a speciality tip that reduces contamination and ensures accuracy. In this article, you shall be informed on the different kinds of speciality tips and how they can be of benefit when it comes to improving pipetting accuracy and speed in the laboratory.
Filter tips enable one to pipette gently while avoiding splashes that are likely to occur when pipetting; this way, what is in one sample, that is, DNA, does not transfer to another sample.
The gel-loading tips should not be used again because there will be cross-contamination from one sample to another. It is very important to recall that each sample should be done with a new tip only, this is to avoid cross-contamination.
The tips should be stored in an aseptic manner and in an ideal world one should not handle the tips to avoid compromising sterility.
