Micropipettes or pipettes, are instruments used to measure liquid ranging between volumes of 1-10000 µl and transfer it from one sample container to another. This is a basic liquid-handling instrument for almost all scientific laboratories.
Types of Micropipettes
There is no 1 way to classify micropipettes. It can vary in a number of ways.
1. Number of Channels
Single Channel Micropipettes
A single-channel micropipette has only 1 channel to aspirate and dispense the liquid. It means you can handle only one sample at a time.
Multi-Channel Micropipettes
Multi-channel micropipettes can handle 8, 12 or 16 samples in one go. It can attach multiple tips at the same time and you can get the work done faster especially if working in high-throughput labs.
2. Volume Adjustment
Fixed Volume Micropipettes
Here the volume a pipette can aspirate and dispense remains the same and you don’t have the option to adjust or choose between a range. They offer consistent and accurate results for repetitive pipetting.
Variable Volume Micropipettes
Variable volume pipettes give you the flexibility to choose the volume you want to pipette (within the given range). You need to set the volume manually on the dial. High-performance pipettes also come with a volume lock feature for enhanced safety and reliability.
3. Operating Mechanism
Mechanical Pipettes
These are the standard pipettes widely used in all laboratories. Mechanical micropipettes operate on a piston-driven system, where users manually set the desired volume using a dial and apply thumb pressure on the plunger to aspirate and dispense liquids.
Electronic Micropipettes
Electronic micropipettes are more expensive than mechanical ones because they have digital controls, programmability and eliminates the element of human error to a certain extent. It has an electronic display and is ideal for high-throughput labs where reproducibility is paramount.
Components of Micropipette
Plunger
The plunger is one of the main components of the micropipette. Use your thumb to press down on the plunger to aspirate and dispense the liquid.
Then, with a firmer push, sometimes called the “blow-out stop,” it ensures a thorough expulsion of any remaining liquid, guaranteeing accurate measurements—a two-step process of liquid control.
Ergonomics are a key point here since lab professionals will be pipetting repeatedly for long hours. A low-force mechanism which does not require excessive plunge force, will minimize the RSI.
Volume Adjustment Dial
By twisting the volume adjustment dial, you dictate the micropipette’s plunger movement, determining your experiment’s liquid dosage. In micropipettes with adjustable volumes, this feature offers precise measurement control, no matter how small or large the quantity is.
Tip Ejector
Keep your hands and micropipette clean by disposing of used tips promptly. Utilize the convenient tip ejector button to effortlessly remove micropipette tips, ensuring a fuss-free and contamination-free experiment environment.
Tip Cone
The tip cone, also known as the shaft, is the crucial component of a micropipette where the disposable tip is inserted. Its primary function is to ensure a snug fit for the tip, ensuring precision in measurements and preventing air leakage. Its adaptable shape accommodates various sizes and styles of tips, allowing for versatile and secure usage without concerns of detachment or disruptions.
Calibration Screw
Inside the micropipette lies a crucial component, the calibration screw. This is what makes accuracy possible. Twisting this tiny screw adjusts the liquid output, fine-tuning the micropipette’s performance. Regular checks and tweaks, as advised by the manufacturer, ensure precision in your measurements, keeping everything flowing smoothly.
Applications of Micropipettes in Laboratory
Micropipettes are used to measure any small amount of liquid samples for testing and research. They are crucial in lab settings like molecular biology and diagnostics, precisely transferring tiny liquid volumes, facilitating diverse experiments. Mastery of their principles is key to effective scientific research and analysis.
Some common applications include:
1. Molecular Biology
2. Biochemistry
3. Cell Culture
4. Microbiology
5. Analytical Chemistry
6. Clinical Diagnostics
7. Pharmaceutical Research
How does a Micropipette work?
Micropipettes operate on the principle of air displacement. They consist of a plunger connected to an internal piston, which moves to two distinct positions:
- Filling Position: When the plunger is depressed to the first stop, the internal piston displaces a volume of air equal to the desired volume shown on the volume indicator dial. This creates a vacuum, drawing the liquid into the tip.
- Dispensing Position: The second stop on the plunger is used solely for dispensing the contents of the tip without drawing in additional air.
How to use a micropipette?
1. Start with choosing the right micropipette and micropipette tips
Select the one that is best for your application. While pipettes are similar in the way they function, what sets them apart is the accuracy and precision of the measurement, ergonomics and general durability of the instrument.
Set the volume based on your requirement and ensure the tips match the volume of the pipettes.
2. Attach the micropipette tip to the micropipette
Don’t use excessive force here because good quality pipettes will be quick and seamless to attach to the tips and should provide a leak-proof seal.
- Immerse the pipette in the liquid at 90 degrees
- Be mindful of your posture and keep the position upright.
- Aspirate and dispense 2-3 times before actually measuring the liquid
3. Forward or Reverse Pipetting
First let’s talk about forward pipetting:
- To aspirate the liquid in the tip, press the plunger to the first stop. Immerse the pipette tip vertically in the liquid.
- Slowly release the plunger while the tip is immersed. The liquid will be aspirated into the pipette tip.
- To dispense the liquid, place the tip on the inner wall of the receiving vessel at a steep angle
- Slowly press the plunger to the first stop to dispense the liquid.
- To empty the tip completely, press the plunger to the second stop.
Now for reverse pipetting
The reverse technique is suitable for dispensing reagents/solutions that have high viscosity or a tendency to foam easily. It is also recommended for dispensing very small volumes.
- To aspirate the liquid in the tip, press the plunger to the second stop and immerse the pipette tip vertically in the liquid.
- Slowly release the plunger while the tip is immersed. The liquid will be aspirated into the pipette tip.
- To dispense the liquid, place the tip on the inner wall of the tube at a steep angle.
- Slowly press the plunger to the first stop.
- Finally, eject the tip and dispose it off
Calibration of Micropipettes
Calibration is conducted through gravimetric testing, which involves weighing the amount of pure water delivered in a single operation of the pipette. The obtained mass is divided by the density of water to determine its volume. Variable volume pipettes should undergo testing at three or more points across their designated range, typically at maximum volume, 50% of maximum volume, and the lower limit of their range.
Here’s a general guide on how to calibrate a micropipette:
1. Gather Materials
- Micropipette(s) to be calibrated
- Appropriate pipette tips
- Distilled water or a calibration solution
- Weighing balance with appropriate accuracy (usually in milligrams)
- Gloves and lab coat for safety
2. Prepare the Micropipette
- Ensure the micropipette is clean and free from any residue.
- Attach a fresh and compatible pipette tip to the micropipette.
3. Pre-Wet the Pipette Tip (Optional)
For some micropipettes, pre-wetting the tip with the liquid being used can help ensure accuracy. Follow the manufacturer’s recommendations regarding pre-wetting.
4. Prepare the Calibration Solution
- Use distilled water or a calibration solution recommended by the micropipette manufacturer.
- Ensure the calibration solution is at room temperature to minimize density variations.
5. Set the Micropipette to the Desired Volume
- Adjust the micropipette to the volume you want to calibrate (e.g., if calibrating a 10-100 μL micropipette, set it to 50 μL).
6. Dispense Liquid into a Weighing Boat or Container
- Dispense the liquid from the micropipette into a weighing boat or a container placed on a weighing balance.
- Note down the initial weight (W1) of the liquid dispensed.
7. Weigh the Dispensed Liquid
- Carefully weigh the liquid dispensed using the weighing balance. Ensure the balance is calibrated and accurate.
- Record the final weight (W2) of the liquid.
8. Calculate the Dispensed Volume
- Subtract the initial weight (W1) from the final weight (W2) to determine the weight of the liquid dispensed (W).
- Convert the weight of the liquid dispensed to volume using the density of the liquid or the known density of the calibration solution.
- Calculate the actual volume dispensed using the formula:
9. Compare with Expected Volume
- Compare the calculated volume dispensed with the expected volume (e.g., 50 μL for a 10-100 μL micropipette).
- Calculate the percent error to assess the accuracy of the micropipette calibration:
10. Adjust if Necessary
- If the percent error is within an acceptable range (typically ±2-5%), the micropipette is calibrated. Otherwise, adjustments may be needed.
- Consult the micropipette’s user manual for instructions on how to adjust the volume settings. Adjust carefully and recheck the calibration until the desired accuracy is achieved.
11. Record Calibration Data
- Keep a record of the calibration process, including the micropipette serial number, date of calibration, volume settings, calibration solution used, measured weights, calculated volumes, and any adjustments made.
12. Final Checks
- After calibration, perform a final check to ensure the micropipette is dispensing accurately and consistently across the volume range.
When is micropipette calibration required?
Micropipette calibration is typically required in the following situations:
Initial Use
New micropipettes should be calibrated before their initial use to ensure accuracy and precision.
Scheduled Calibration
Regular calibration intervals are recommended to maintain the accuracy of micropipettes over time. The frequency of calibration depends on factors such as the frequency of use, the criticality of the measurements, and the manufacturer’s recommendations.
After Maintenance or Repair
Calibration should be performed after any maintenance or repair work on the micropipette to verify that it meets the required specifications.
Change in Operating Conditions
If there is a significant change in the operating conditions, such as temperature or altitude, recalibration may be necessary to account for these factors’ effects on the micropipette’s performance.
Compliance Requirements
Laboratories may have regulatory or quality assurance requirements that mandate regular calibration of micropipettes to ensure traceability and compliance with standards.
Where do we get the best micropipette for the lab?
When purchasing a micropipette for your lab, consider key factors such as accuracy, precision, ergonomics, and ease of maintenance. Research the brands and models, compare specifications, and read user reviews to make an informed decision. Evaluate additional features like adjustable volume settings and compatibility with automation systems. Set a budget and balance costs with desired features. Check warranty coverage and customer support options for added peace of mind.
Cleaning and Maintenance of Micropipettes
1. External Cleaning
- Remove and Clean the Tip Ejector: Begin by detaching the tip ejector and giving it a thorough wipe-down.
- Wipe Down All Exposed Surfaces: Take a lint-free cloth or tissue and carefully wipe all visible parts of the micropipette, including the body, buttons, operating rod, and tip holder. Be diligent in cleaning any scuffs, marks, or accumulated debris in hard-to-reach areas.
- Use a Brush for Stubborn Debris: If there are persistent stains or dirt, consider using a soft-bristled brush to gently scrub the affected areas.
- Reassemble and Allow to Dry: Once the exterior surfaces are clean, reattach the tip ejector and ensure it is securely in place. Leave the pipette to air dry completely before further use.
- Final Wipe with Cleaning Solution: Finish the cleaning process by wiping down the outer surfaces once more with a cleaning solution to remove any remaining residue. Allow the alcohol to evaporate fully before returning the pipette to service.
2. Internal Cleaning
Cleaning the inside of a pipette should be handled by trained personnel to avoid incorrect reassembly, which can damage the micropipette and affect its performance, leading to decreased accuracy and potential leakage.
- Disassemble the Micropipette: Carefully take apart the pipette, placing the upper part in a clean, dry area.
- Wipe with Alcohol-Coated Wipes: Use alcohol-coated wipes to thoroughly clean the entire interior, including the body, connecting nut, tip holder, O-ring, seal, and the stainless steel surface of the piston. Ensure the piston is completely dry to prevent corrosion.
- Allow Alcohol to Evaporate: Let the alcohol evaporate fully from the interior of the pipette.
- Check for Lubrication Needs: Refer to the instruction manual to determine if any parts, like the piston assembly and seals, require lubrication. Follow the manual’s guidance for reassembly, ensuring proper alignment and placement of components.
Maintaining Micropipettes
When the pipette is not in use it should be stored in an upright position. The pipette should be inspected prior to use each day for any dust or contamination on outside surfaces. Special attention should be given to the tip cone. No solvent other than isopropanol should be used to clean the pipette. If the pipette is used daily, an internal parts inspection should be performed every three months.
Choosing the right micropipette for your application
- Ensure that the micropipette can accommodate the desired range of liquid volumes for your pipetting needs.
- Verify if the micropipette features a universal tip cone to accommodate various types of pipette tips.
- Check if the micropipette is autoclavable at the necessary temperature to ensure proper sterilization.
- Check if the micropipette is UV resistant so that they can be kept inside the hood even when the UV mode is on.
- Assess the ergonomic design of the micropipette for smooth and comfortable handling during use.
- Confirm if the micropipette is calibrated to guarantee precise dispensing of liquids.
- Evaluate the accuracy and precision of the micropipette’s readings to ensure compliance with ISO standards.
- Ergonomics is a key factor in choosing a pipette because repetitive strain injury is common amongst lab personnel who pipette regularly. Low-force tip ejection and minimal plunge force are crucial.
Accumax Lab Devices specializes in manufacturing high-precision liquid handling instruments for top-tier laboratories worldwide. With a focus on innovation, it offers an advanced range of micropipettes designed to enhance user experience within real-world laboratory settings. Especially our range of FAB and FAB LF pipettes, which are specially designed for accuracy and precision with excellent ergonomics to elevate your pipetting experience like never before.
Micropipette FAQs
1. Can I use any brand of pipette tips with my micropipette?
Whether you can use any brand of pipette tips with your micropipette depends on its tip cone design. If your micropipette has a universal tip cone, it means it’s compatible with a wide range of international pipette tip brands, as long as they’re suitable for your micropipette’s volume capacity.
2. What’s the best way to sterilize my pipette before use?
To clean your micropipette before using it, first, check if it can be sterilized using an autoclave. If it can, follow the instructions in the manual to know the right temperature and duration for sterilization. Make sure to consider the type of liquid you’ll be using it for.
3. Is there a simple way to check if my micropipette is calibrated correctly?
Set it to the usual volume, then dispense water five times. Weigh what you piped out on a scale. If it matches up nicely with the ISO standard, your micropipette is good to go. If not, it’s time for a recalibration.
4. How frequently should I recalibrate my micropipette?
For regular use, it’s good to check your micropipette’s calibration every 3 to 6 months. Following the ISO 8655 standard, it’s recommended to have it calibrated annually.
5. How to adjust the volume of a micropipette?
To adjust the volume on your micropipette, look for the display showing numbers indicating the volume range. If you have a fixed-volume micropipette, the range is predetermined. However, if you have a variable volume micropipette, you can adjust it within the given range by using the rotational dial located at the top of the micropipette plunger. Alternatively, you can consult the manual for specific instructions on changing the volume.
6. Why is it important to avoid touching the tips of the micropipette?
When you touch the tips of a micropipette, you risk transferring oils and other substances from your fingers onto them. This can interfere with the accuracy of volume measurements and potentially contaminate your samples. To maintain precision and avoid contamination, it’s best to handle the micropipette tips only with the instrument itself.
7. What happens if I release the plunger of the micropipette too quickly?
Releasing the micropipette plunger too quickly can lead to inadequate liquid draw up and dispensing, causing potential inaccuracies in your measurements.
8. What should I do if my micropipette isn’t working right?
If your micropipette isn’t working properly, it’s time for some troubleshooting. Start by double-checking if it’s properly calibrated and if the volume setting is correct. Ensure that the pipette tips are securely attached and not damaged. If the issue persists, you might need to clean or maintain the micropipette according to the manufacturer’s instructions. If all else fails, it might be time to consult with a colleague or contact technical support for further assistance.
9. Can my micropipette handle different types of liquids?
Your micropipette is designed to handle a variety of liquids, whether they’re watery solutions, viscous substances, or even oils. As long as you’re using the appropriate tip size and technique, your micropipette can smoothly pipette different types of liquids.
Aanak Goswami
12+ Years of experience in generating growth for organisations. Having customer management skills with experience of Research, Institutional, clinical diagnostics, Healthcare and Biopharma customers.
