Pipette tips are arguably among the most commonly used equipment in laboratories across the globe. These small and expendable components are an essential component of a large number of scientific procedures and are used for the accurate and reproducible transfer of liquids. From the research laboratory to the clinic or industry, pipette tips are used for experiments, diagnostics, and quality control testing. In this article, we will explain what pipette tips are, their importance in different applications, and how to use them correctly.
Pipette tip is primarily used with micropipettes – instruments that are used to dispense and/or aspiration small volumes of liquid. The tips are standardized and normally made from polypropylene and are offered in several sizes to enable the holding of varying quantities of liquid, though in small amounts such as microliters or milliliters. Pipette tip is used mainly to deliver liquids from one container to the other in a controlled and contamination-free manner during several laboratory processes.
The most fundamental and probably the most frequent application of pipette tip is used in transferring and measuring liquids. In most scientific investigations and techniques, it is very important to aspirate accurate volumes of reagents, samples, or solutions. Pipette tips are used to pick up and deliver very precise volumes of liquid so that the results obtained are significantly accurate. This accuracy is particularly important in experiments where even slight changes in the volume can result in large errors or variability.
In molecular biology, pipette tips are used for such processes as DNA and RNA extraction, PCR setup, and sample loading for gel electrophoresis. Due to the level of accuracy that is needed in these processes, pipette tips cannot be done away with. For instance, while performing PCR, one requires precise measurements of reagents such as DNA templates, primers, nucleotides, and polymerase enzymes to enhance the process of amplification.
Preventing Contamination
Another important utility of pipette tips is to avoid the carry-over of a certain sample or reagent into another sample or reagent. Contamination is extremely damaging to the experiments since it affects very important experiments such as DNA sequencing whereby small amounts of contamination will lead to wrong results.
Employment of Filtered Pipette Tips
To minimize the chances of contamination, filtered pipette tips are used by many laboratories around the world. These tips have a small filter at the narrow end so that aerosols and liquid contaminants cannot get into the pipette. This is particularly important when using or processing volatile or hazardous substances to safeguard both the user and the samples.
Single-Use Disposable Tips
The fact that pipette tips are generally single-use also serves to further safeguard against cross-contamination. This way the chance of contamination of a sample or reagent from the previous sample is reduced since a new tip is used for each sample. This is common practice in many laboratories, particularly in clinical diagnosis where the integrity of each sample has to be preserved.
Application-Specific Pipette Tips
Depending on the various uses that are to be made of the pipettes, there are specific pipette tips that are used to address specific requirements. These tips can be made of different materials, have different shapes, and serve different purposes in a laboratory.
Regular tip pipettes are meant to allow as little of the liquid as possible to stick to the inside of the tip. This feature is particularly useful when dealing with highly viscous liquid or when transferring very small volumes as it discharges almost all the liquid in the sample. Low-retention tips are especially employed in molecular biology and biochemistry because accurate measurements are vital in those fields.
Extended-Length Pipette Tips
Large pipette tips are longer than normal tips and are used to aspirate from deep down a tube without getting to the side walls, to reach the bottom of microcentrifuge tubes for instance. This is important in avoiding cross-contamination and ensuring that the right volumes of liquids are dispensed. Long-shanked tips are mostly applied in cases where there is a need to aspirate or dispense fluids into or from thin-walled or deep-well receptacles.
Wide-Bore Pipette Tips
Wide-bore pipette tips are used in situations where the internal diameter of the pipette tip is larger at the end and is used for transferring the viscous liquids or samples that may be damaged by the narrow end of the pipette tips. These tips are particularly applied in cell culture and tissue engineering where manipulation of cells should be done gently.
To minimize errors and cross-contamination, it is necessary to adhere to guidelines for using pipette tips.
Ensuring Proper Attachment
It is very important to make sure that the pipette tip is firmly in place before using it on the pipette. If the tip is loose or not well attached, there will be problems of air leakage hence wrong measuring results. Almost every pipette has a feature that aids in holding the tips in place and removing them without contacting the liquid.
Avoiding Air Bubbles
This is because if the liquid is haphazardly drawn into the pipette tip, it can result in the formation of air bubbles. This is because when drawing liquid into the container, air bubbles interfere with the volume of the liquid drawn hence a wrong measurement is obtained. If there are bubbles, they must be removed before the liquid is dispensed The bubble to be removed.
Consistent Pipetting Technique
The pipetting technique should also be consistent to yield accurate results. While dispensing a liquid, the tip should touch the receiving vessel and the liquid should be dispensed gently to avoid droplets and hence losing some of the sample. Pipetting angle should also be correct which is usually between 20-30 degrees from the vertical position.
Pipette tips are considered one of the most important aspects of the laboratory since they are responsible for the accurate dispensing of liquids as well as avoiding various types of contamination and are used in numerous scientific applications. In all these applications, pipette tips that are appropriate for the intended use will enable one to obtain accurate and consistent results. Therefore, by familiarizing with the different types of pipette tips and their application, together with adherence to the best practices, the work of scientists and technicians will be improved in terms of quality and productivity.
Low-retention pipette tips are those that allow as little of the liquid as possible to stick to the inside of the tips to allow for as much liquid to be pipetted as possible. This is especially important when working with small volumes or viscous liquids because even a small volume left in the system may cause large measurement errors.
Autoclavable pipette tips are pipette tips that consist of a small filter that helps to prevent aerosols and liquid contaminants from getting into the pipette thus avoiding contamination of samples. This is especially important when handling flammable or toxic materials so as not to harm the user or contaminate the samples.
Most pipette tips are manufactured from polypropylene, which is reusable, however, pipette tips are disposed of after use to avoid contamination. However, few laboratories engage in recycling programs for lab plastics such as pipette tips for environmental conservation.