Pipettes and pipetting instruments are essential for ensuring the integrity and accuracy of data in most laboratories. How accurately and consistently a pipette can deliver a specified volume of liquid directly impacts key lab functions and the quality of the data it generates. However, common pipetting errors can devalue the quality of a laboratory's results.
“The influence a pipette can have over the quality of results is quite astonishing. An uncalibrated pipette, or a technician with poor pipetting skills, can quickly undermine a lab’s ability to generate meaningful, reliable, and reproducible results. Additionally, it often requires considerable time and resources to identify the source of the issue and correct the problem.”
LouAnn Evans, Director of Marketing, Pipette.com
It’s clear that understanding common pipetting errors and knowing how to prevent them is crucial for laboratories. Let’s explore the top 5 common pipetting mistakes and get insight on how you can stop them from happening.
Pipetting Error #1: Poor Pipetting Technique
Poor pipetting technique affects a lab’s ability to produce meaningful results in an efficient timeframe. Signs of poor pipetting techniques can include inconsistent results, poor calibration curve values, or unreproducible data.
Advice to ensure your team exhibits good pipetting techniques in your laboratory includes:
- Require every technician to undergo regular pipette technique testing
- Perform routine calibration checks on all your pipettes
- Try to only use the same type of tip that the pipette was calibrated with (in accordance with ISO8655)
- Regularly review calibration and quality control data for inconsistencies or other obvious signs of poor pipetting.
How to Assess if a Technician Has Poor Pipetting Technique?
Ask the technician to weigh out the same volume of liquid using a pipette that is known to be calibrated and in good working order. Determine the error allowance based on the pipette’s error tolerance at the volume level being measured.
If the technician cannot deliver consistent results, be sure to take appropriate measures to improve their accuracy and technique.
Pipetting Error #2: Inadequate Pipetting Education
To avoid having a laboratory full of technicians making pipetting errors, it’s crucial they have access to the right education and training. The more you can educate and assess your team on good pipetting practices, the less likely you’ll encounter some of the most common pipetting errors.
When devising a pipetting education/assessment plan, be sure to include the following critical pieces of information:
- Explain the importance of good pipetting techniques as well as how pipetting errors can impact data quality and compliance requirements.
- Help your team understand how a pipette works. For an informative guide on how air displacement pipettes work, click here.
- Demonstrate how to visually inspect a pipette before use and what signs to look for that may indicate a pipette should not be used.
- Have established processes for sending pipettes out for calibration and maintenance service that includes what to do while a pipette is out for service.
- Compile a list of good pipetting techniques crucial to your lab. Examples could include:
- Use consistent speed when drawing and dispensing liquids.
- Always pre-wet a tip when working with low-viscosity liquids, volatile solutions, or water-based solutions.
- How to select the best pipette for a given application.
Pipetting Error #3: Use of an Uncalibrated Pipette
Every piston-operated dispensing device you use for generating results must be checked and calibrated on a regular basis. Over time, the mechanisms within a pipette can shift and result in a different volume of liquid to be dispensed than what was intended. To ensure the accuracy of your measurements, it’s important to only use calibrated pipettes that are known to be in good condition.
Having your pipettes regularly calibrated, in accordance with their manufacturers’ recommendations will help ensure every test result your lab produces is valid and of sound integrity.
Data created using samples prepared with an uncalibrated pipette could be subject to scrutiny – or even invalidated– if an auditor or client determines use of an uncalibrated pipette violates a standard or contractual obligation.
To prevent using a pipette with an expired calibration certificate, track each pipette’s calibration and maintenance history and work with a calibration company that can help keep your equipment on track.
💡Pro-Tip: To ensure your team has the right pipette they need, when they need it, consider purchasing certified refurbished pipettes!
Pipetting Error #4: Using The Wrong Pipette For Your Application
When accuracy and precision are on the line, be sure to use the right pipette for your specific need and application. Failure to do so can result in introducing higher levels of error than necessary, making it harder to achieve consistent, precise results.
Common examples of using the wrong pipette include:
- Use a pipette to dispense a type of liquid it is not normally used to dispense. For instance, if a pipette that’s normally used for viscous solutions is used to transfer a low-viscosity liquid, the results could be less accurate.
- Measuring a volume is not ideal for the pipette. For instance, when dispensing 10uL of calibration standard, use a pipette whose lowest amount of error is around the 10uL mark, not one where the 10uL volume has its highest error values. This is generally at the midpoint of a pipette’s volume range, but check your pipette’s manufacturer's specifications to be sure.
- Use a “rugged” pipette for precise measurements. It’s common for labs to have “spare” pipettes that are uncalibrated that they use when precision and accuracy aren’t paramount, like when transferring a prepared sample into a vial for analysis. However, they should never be used to prepare solutions that require precise care and attention.
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Pipetting Error #5: Poor Pipette Maintenance Practices
Pipettes often go between 6 - 12 months between calibrations – a lot can happen to a pipette in between calibration services if it’s not properly cared for and maintained. If regular maintenance isn’t applied, or the pipettes aren’t cared for properly, they can easily slide out of their specified precision and accuracy ranges, resulting in erroneous measurements.
To help keep your pipettes accurate and in good condition, be sure to follow these maintenance practices:
- Regularly check pipettes for accuracy. Start each week by performing simple gravimetric tests to ensure each pipette is functioning correctly.
- Clean your pipettes regularly. Follow the manufacturer’s instructions for how to clean and visually inspect your tools.
- Adhere to the pipette’s recommended schedule for calibration and maintenance tasks. If a manufacturer suggests having the pipette calibrated every 6-months, it’s wise to adhere to that. Not every pipette will have the same recommendations, the pipette’s manufacturer, size, style, and usage level can all impact when you should have a pipette calibrated.
- Do not use pipettes that have been dropped, appear broken, or have visual residue/contamination at the base of the barrel.
- Label pipettes based on their intended use. To prevent cross-contamination or having a pipette used inappropriately, label your pipettes.
Master Pipetting Maintenance with Pipette.com
Keeping on top of your lab’s pipettes is crucial, but that doesn’t make it easy to manage. Let the calibration experts at Pipette.com help keep your pipette maintenance program easier to manage.
We are a full service calibration company with years of experience calibrating, repairing, and certifying pipettes. We help thousands of clients each year keep their pipettes in top-condition and meet regulatory requirements such as FDA, ISO 8655, cGLP/cGMP, ISO 17025 and we can help you too. Learn more about our pipette calibration services on our website.