How To Sterilize Pipette Tips?

Pipette tips are among the widely used labware in laboratories, and ensuring that they are sterilized well is important for the accurate replication of experiments. It minimizes the risks of cross-contamination, which is very harmful to the results of experiments, especially when biological samples are used or when handling dangerous chemicals is involved. This article provides the reader with all the information they may need about the methods of sterilizing pipette tips, how to choose the right method and what should be done and avoided to maintain the sterility of the pipette tips. This article presents much attention to the issue of sterilization of pipette tips. 

Why is the Sterilization of Pipette Tips Important?

The pipette tips are used in laboratories to transfer measured quantities of liquids with the help of the tips, which are graduated. Contamination is always wrong when dealing with DNA samples, cell cultures, or chemicals. The proper way of sterilizing pipette tips is to ensure that no other substance or microorganisms can be transferred from one sample to another to increase the experiment's cleanliness. Besides, sterilization is crucial in reducing the spread of pathogens in a laboratory that handles pathogens or biohazardous products. 

Methods of Sterilizing Pipette Tips 

The following are the different methods of sterilizing pipette tips used in laboratories. Depending on the type of samples to be prepared, the degree of sterility required, and the equipment available in the laboratory, the following methods are used in preparing the samples. 

Autoclaving 

Pipette tips are normally sterilized by autoclaving, the most common method. It involves using steam pressure and a temperature of approximately 121°C (250°F) to kill microorganisms and spores. Autoclaving pipette tips is often possible because most are made from polypropylene, and the process is easy. 

Procedure for Autoclaving Pipette Tips

• Place the pipette tips in an autoclave bag or any other suitable container. Ensure the container is not sealed up well to allow the steam to pass during the process. 
• Put the container in the autoclave, but do not pack them closely to allow equal heat distribution in the autoclave. 
• The recommended temperature is 121°C, while the pressure should be 15 psi for 15-20 minutes. 
• Once the cycle is complete, switching off the autoclave to cool before removing the tips is possible. 
• After sterilization, the tips should be put into a clean and dry state before they are utilized. 
• Autoclaving is useful in most laboratory operations, but it can not be applied on heat-sensitive tips or when sterilizing some heat-sensitive materials.  

UV Sterilization 

UV sterilization is another method of sterilizing pipette tips, particularly those that cannot be autoclaved. UV light is one of the most effective ways of disinfecting bacteria, viruses, and other pathogens because it changes their genetic makeup. However, UV sterilization is surface-dependent, and therefore, it only impacts the outer surface of the pipette tips. 

Procedure for UV Sterilization:  

• The pipette tips should be in a UV sterilization box or under the lamp. 
• Ensure that all the surfaces of the pipette tips are exposed to UV light. 
• Usually, tips are optimally cleaned through UV lights. So, depending on the intensity of the UV light, the pipette tips must be sterilized for 15-30 minutes. 
• The tips should be used immediately after sterilization or in a sterile container. 
• UV sterilization was effective in surface sterilization but could not eliminate all the contaminants, especially those that may be present in the tips. Hence, it is used more as an adjunct to sterilization than as the primary mode. 

Chemical Sterilization 

Chemical sterilization can be a liquid sterilizing agent used to sterilize pipette tips or a gaseous sterilizing agent. Some of the chemicals used include ethanol, bleach, and hydrogen peroxide.  

Procedure for Chemical Sterilization: 

• Put the pipette tips in a beaker with the chosen chemical disinfectant solution. Ensure that the tips are rounded off to the last cent. 
• Allow the tips to remain submerged in the tips for the necessary time, which is 15-30 minutes for ethanol or bleach solution. 
• After that, the tips should be washed with sterile water to remove the chemicals that may be remaining on the tips. 
• These tips must be dried before use or put in any other sterile state. 
• Chemical sterilization is very effective in eradicating many types of microorganisms. Still, it involves the use of chemicals that must be properly rinsed off after use to avoid contamination of samples. 

Measures for Sterility 

This is not the end of it; there is another process, which is sterilizing pipette tips. Since sterility is a very crucial aspect in the laboratory, the following should be done in your work: 

• Handle Tips with Sterile Gloves: In this case, it is necessary to have sterile gloves whenever working with the sterilized pipette tips. 
• Store Tips in Sterile Containers: Pipette tips should be stored in closed systems to prevent the tips from becoming contaminated with debris. 
• Avoid Repeated Handling: In general, minimize contact with the sterilized pipette tips' hands as much as possible. As the two authors above mentioned, handling also increases the level of contamination. 
• Use Sterile Technique: If you are using pipette tips for sterility, then make sure that you follow the right sterility measures, like when you are in the laminar airflow.  

Limitations of Sterilization Methods 

As it has been said earlier, each method of sterilization has its drawbacks: If the material used in pipette tips is not heat resistant, then the pipette tips may get destroyed, or the features of the tips may change during autoclaving. UV sterilization is not very useful for internal sterilization; chemical sterilization requires washing after the sterilisation process. Thus, choosing one of the methods that should be most suitable to the requirements and conditions of the laboratories is recommended.  

Conclusion 

This is a crucial factor that enhances the reliability of laboratory experiments; therefore, pipette tips should be sterilized. Autoclaving is the most recommended method for pipette tips. In contrast, other methods include UV and chemical sterilization depending on the type of pipette tips and the experiments to be conducted. This way, you will be able to select the right sterilisation method and avoid contamination of pipette tips, which will, in turn, make your results safe.  

FAQs 

Q1. Can I sterilize all types of pipette tips using the same method?

No, it usually depends on the requirement. For instance, some tips may not be heat stable and, therefore, autoclavable, while others may be UV or chemically sterilisable. 

Q2. How many times it is possible to autoclave autoclave pipette tips? 

If pipette tips need to be sterile for the experiment, then pipette tips must be autoclaved. If used again, they should be washed to ensure they do not transmit the diseases to the next patient or any other surface the cloth touches. 

Q3. What is the best method of sterilizing pipette tips? 

Therefore, it is important to emphasise that even though autoclaving is considered the safest and the most efficient method of pipette tip sterilization, it depends on the type of material and characteristics of the experiment.