The micropipette is an instrument of medical personnel, researchers, and scientists used in laboratories. Therefore, it is essential to prevent contamination during pipetting to obtain reliable results. For this reason, knowing how to identify possible contamination factors is necessary. Those factors may change the precision and quality of these results.
One of the initial steps you should follow to avoid contamination in the laboratory setting is the correct use of Personal Protective Equipment (PPE). The PPE is recommended for all types of laboratory experiments. The most used include hand gloves, safety glasses, shelter, mask, protective footwear, etc.
This post will increase your knowledge by presenting the types of contamination in pipettes and the ways to avoid them.
Different Contaminations in Pipettes and How to Avoid Them
Laboratories are a good place for microorganisms, as many different products and objects pass through each day. When dirt gets stuck in the bench, there is a great risk that the sample being handled there will be disturbed during pipetting. Therefore, it is essential to keep these surfaces clean regularly. Each laboratory works with different samples, so it is important that the site is cleaned according to the routine that is carried out there. The most commonly used products for cleaning laboratory benches are water, bactericidal soap, 70% alcohol and sodium hypochlorite (bleach).
You may find many laboratory activities in which suspensions of solid or liquid particles in gas or aerosols are formed. It is mainly when you use air displacement pipettes. And these aerosols have been established as the major contributors, among others, to pipetting contamination. For instance, they can transfer to the micropipette when you use non-filter tips, which causes contamination in subsequent samples
Now, look at the most common laboratory contaminants (MICROLIT, 2021):
Pipetting: Micropipette Contamination – Sample
It is the result of using a contaminated micropipette or non-certified tips. In this way, you can avoid sample contamination during pipetting with the use of sterile tips, or by cleaning or sterilizing the micropipette.
Tips have three categories of purity grades:
- No purity guarantee
- Certified free of contaminants such as DNase, RNase, and endotoxins
- Sterilized devoid of microbial life
Look at the guidelines to avoid contamination of the sample micropipette:
- You need to select a tip with the cleanliness class for your application.
- You should use positive displacement tips or disinfected filter tips. Alternatively, it is also possible to use filters on certain brands of micropipettes. Thus, the filters prevent aerosols from reaching the body of the micropipette, being a potential factor in the subsequent contamination of the sample.
- Always change tips after each sample.
- Sterilize the pipette and other components that may contaminate the sample.
Pipetting: Sample Contamination – Micropipette
It happens when the sample or its aerosol particles enter the micropipette’s body during pipetting. Therefore, you should follow certain steps to minimize this risk of contamination:
- Always keep the micropipette in an upright position during the procedure and store it in an upright position. This prevents liquids from leaking out and contaminating the equipment.
- Eject the nozzle instantaneously after use to avoid the aerosols’ entry.
- Gradually release the button on the micropipette to avoid aerosol development and spillage of samples inside the equipment.
Sample Contamination for Micropipette
Pipetting: sample – sample contamination
sample-to-sample contamination happens when transportation of aerosol or liquid residue from one sample to another is made. This happens when the same tip is used multiple times. You can avoid carry-over contamination by:
- Always change the tip after each manipulation.
- Use positive displacement tips or filter tips. This way, you can prevent sample aerosol from infiltrating the micropipette body. So, you can prevent the subsequent sample from contamination.
- If the micropipette is contaminated, as you suspect, autoclave or clean the equipment by following the manufacturer’s instructions.
You can clean some micropipettes easily or only the parts of them that have become contaminated. It may happen when it is used improperly (MICROLIT, 2021).
Remember: You must not sterilize filter tips must. However, it is recommended to use sterile products.
After sterilizing, you should dry and cool the micropipettes or sterilized parts to room temperature. As heated plastic parts can easily be stretched or damaged, micropipettes should only be screwed back on after they have absolutely cooled down (MICROLIT, 2021).
MBP INC is one of the top leading suppliers of the highest quality filter and non-filter tips, PCR products, and many other lab consumables. We strive to help our community maintain a high standard and quality products.
MICROLIT, 2021. Micropipette Product Guide. [online] MICROLIT. Available at: <https://www.microlit.us/micropipette-product-guide/> [Accessed 9 December 2021].