Pipette Calibration Using a Balance

Pipette performance verifications according to ISO 8655 are essential to ensure your liquid handling precision instrument is working accurately.

To maintain consistent accuracy of pipetted volumes, pipettes should be calibrated and tested regularly. Pipette calibration is usually performed by a specialized service provider, who will provide a calibration certificate that includes an assessment of the pipette’s measurement uncertainty. In the intervals between calibrations, routine pipette testing carried out by the user ensures a pipette continues to perform according to its specifications. A simple routine test quickly confirms that the instrument is still fit for its intended use and drastically reduces risks of out-of-tolerance (OOT) results.

How does weighing relate to pipette performance?

One of the most important methods for checking pipette performance is using a balance to weigh the liquid delivered by the pipette. The volume of the liquid is then calculated and compared to the expected value. The International Organization of Standardization (ISO) details the requirements for the gravimetric reference measurement procedure for the determination of volume. ISO 8655-6 includes minimum requirements for balances according to the nominal volume of the pipette under test. ISO updated the standard for piston-operated volumetric apparatuses (POVA) in 2022.

Watch to learn more about the XPR105MCP, which fulfills the ISO 8655 requirements for multichannel pipette calibration devices. This video covers the following points:

• Increasing the speed of your multichannel pipette calibrations 
• Automating data collection and calculations with Calibry PC Software
• Audit-readiness and certificate storage

The gravimetric reference measurement procedure for the accurate determination of volume is described in part 6 of ISO 8655:2022.

The balance used for testing shall be chosen according to the minimum requirements specified in ISO 8655-6:2022, Table 1, depending on the nominal volume of the apparatus under test. The balance parameters are defined so that the expanded uncertainty in use is less than one-fourth of the maximum permissible systematic error of the apparatus.

After 20 years, the ISO 8655 standard was updated in May 2022. The changes in ISO 8655:2022 bring the standard up to date with current metrological principles to ensure accurate and reliable results.

Read more here about the updated ISO 8655:2022 requirements for pipettes:

It can be difficult to ensure an error-free pipette calibration workflow. Here are some of the key challenges faced by today’s labs:

• Training technicians to have proper pipetting technique
• Choosing the correct equipment for calibration
• Ensuring a controlled environment, particularly for preventing evaporation and unstable readings
• Completing calibrations under time pressure
• Maintaining focus during repetitive and monotonous calibrations, particularly for multichannel pipettes
• Transferring data without errors and correctly completing calculations
• Maintaining organized document storage for audits

Quality standards and guidelines, such as ISO 8655, ISO 17025, Good Laboratory Practice (GLP), and Good Manufacturing Practice (GMP), require regular calibration and/or verification of measuring instruments at specified intervals. This monitoring, calibration, control, and routine testing of instruments is intended to ensure metrological traceability and provide evidence of the pipette’s “fitness for purpose.”

METTLER TOLEDO’s Good Pipetting Practice™ (GPP™) program includes quality assurance measures for pipettes and simple, straightforward recommendations for their selection, installation, calibration, and operation. It provides a comprehensive, systematic approach to maximizing pipetting accuracy and reproducibility.

A combination of three complementary activities ensures that your pipette delivers reliable results every day:

1. Pipette calibration and preventive maintenance – performed by a service provider
2. Pipette routine testing – performed by the user
3. Pipetting user training – delivered by a pipetting expert

Routine testing (also referred to as a pipette test, performance test, or quick check) provides reassurance that a pipette continuously delivers accurate and reliable volumes between calibrations. Compared to calibration, routine testing provides additional security because it checks the system of “user and pipette” under daily laboratory conditions, mimicking the actual pipetting process. This is particularly important for critical applications because the user technique can be a dominant source of pipetting uncertainty.

The type of sample, environmental conditions (humidity, temperature), SOPs, and user-defined tolerances determine to what extent and how frequently each activity should be performed. Good Pipetting Practice™ (GPP) supports you with creating a risk-based performance verification plan. Learn more about GPP™ and take an online pipetting risk check here: Good Pipetting Practice Risk Check

Our team of experts in pipettes, balances, and calibration is happy to provide support. Please do not hesitate to contact us to discuss your requirements.

Information about GPP, pipette service intervals, or achieving ISO 8655:2022 compliance is available here: Services for Pipettes

For questions about pipette calibration balances, software, and accessories, please use the contact form below.

Your work is too important to risk inaccurate or inconsistent data due to poor pipette performance. Rainin pipette service is rigorous and comprehensive, executed by highly trained and experienced technicians who know your pipettes. Make certain these important research tools deliver the reliability and reproducibility your work depends on with Rainin Service.

Reliable pipette service is part of the Rainin 360+™ system for optimal liquid handling results. Precision pipettes, high-purity tips, and expert service are all backed by innovative tools, software, and training to ensure exceptional performance across your workflows.

Whether you prefer mail-in or onsite pipette calibration, we offer a range of pipette calibrations that include ISO 8655 and ISO 17025-accredited pipette calibration to meet your regulatory needs. Rainin pipette service is rigorous and comprehensive, and it makes certain your pipettes deliver with the reliability and reproducibility your work depends on. 

Simply put, when it comes to pipette service, no other provider can match the depth, breadth, and level of process integrity and control that METTLER TOLEDO Rainin offers.

To perform ISO 8655-compliant calibrations on a laboratory balance, METTLER TOLEDO Laboratory Weighing offers a comprehensive portfolio for the calibration of single and multichannel pipettes. Each balance can be connected with our Calibry PC Software, which guides technicians step-by-step through procedures and performs calculations automatically. 

With SmartCheck, you can test a pipette's accuracy between calibrations – right at your bench – in 60 seconds or less. Know that your pipettes are dispensing accurately and trust your data!

When used in conjunction with PipetteX™, the pipette testing data you collect using SmartCheck is automatically recorded into each pipette’s calibration and service record. PipetteX controls routine test methods, flags pipettes in the event of routine test failure, and sends notifications if action is needed. It reminds you when testing or calibration is due and supports compliance with 21 CFR Part 11.

ISO 8655-6 requires that single-channel pipette volumes of less than 20 μL be measured on a six-place (microgram) balance. The XPR26PC was designed specifically for the measurement of these small volumes. The light barrier provides efficient hands-free operation with automatic opening and closing of the evaporation trap lid. Throughput is further improved by the large 10 mL waste container, which enables you to pipette continuously without interruption.

The supplementary Calibry PC software allows you to fulfill ISO 8655 and 21 CFR Part 11 conformity. Its simple user interface guides you through pipette calibration and testing procedures. Calibry stores all results in a secure database, informs you when upcoming tests are due, and generates customized reports.

An XPR Micro or Analytical Balance equipped with an evaporation trap is a perfect solution for calibrations and routine performance verifications of single-channel pipettes according to ISO 8655 requirements.
An XPR36/56 Microbalance with an evaporation trap fulfills ISO 8655 requirements for pipettes with nominal volumes as low as 0.5 μL , while an XPR205 Analytical Balance with an evaporation trap is suitable for testing pipettes with volumes of 20 μL and greater.
The evaporation trap allows for higher throughput calibrations with fewer interruptions to empty the waste container.  The supplementary Calibry PC software guides you through pipette calibration and testing procedures. It supports accurate and traceable pipette calibrations according to ISO 8655 and 21 CFR Part 11 requirements.

The XPR105MCP is a high-speed solution to perform calibrations and routine performance verifications of multichannel pipettes with up to 12 channels according to ISO 8655 requirements. With a readability of 10 μg and repeatability of 15 μg, the system fulfills ISO 8655 requirements for multichannel pipettes with dispensing volumes as small as 0.5 μL.

The system has been carefully designed with a single load cell to ensure fast and equal performance for all channels. Up to 12 pipette channels can be measured in one dispense and the 360 measurements needed for a full calibration (12 channels, 3 ×10 repetitions) can be completed within 25 minutes. The load cell is protected from any leaks and spills to ensure lifelong performance.

The supplementary Calibry PC software guides you through pipette calibration and testing procedures. It supports accurate and traceable pipette calibrations according to ISO 8655 and 21 CFR Part 11 requirements.

Calibry PC software is ideal for managing ISO 8655 calibrations and routine tests of single and multichannel pipettes. Its simple user interface is easy to work with, and all data can be managed in compliance with 21 CFR Part 11. Calibry comes with pre-defined calibration methods for every pipette volume, or you can create your own custom test methods. It performs all calculations for efficient and seamless calibration processes, stores data from each pipette in a secure database, and generates customizable reports. 

LabClimate PC software is an environmental measurement system consisting of sensors for temperature, pressure, humidity, and corresponding reporting software. The LabClimate software collects the data automatically and displays it clearly on a PC user interface. Data can also be synchronized directly with Calibry software or exported to Excel.