Pipettes are an indispensable tool in laboratories, offering precise and accurate liquid handling capabilities. To maintain the reliability of laboratory measurements, it is crucial to calibrate pipettes according to recognized standards. The latest international standard, ISO 8655:2022, introduces significant updates that enhance the accuracy and precision of pipette calibration.

In this blog, we will delve into the key changes introduced by ISO 8655:2022 and explore their implications for pipette users. So, let us embark on this journey together and uncover what you need to know about pipette calibration!

The Influence of Pipette Tips

ISO 8655:2022 places renewed emphasis on the role of pipette tips in achieving accurate measurements. Now, tip manufacturers must demonstrate that their tips meet the specified requirements and permissible errors. Calibration results are valid only for the specific type of tip used during calibration. This means that if you use different tip types, separate calibrations are necessary for each type. By acknowledging the impact of pipette tips, this update ensures that the entire pipetting system is considered for accurate results.

Maximum Permissible Error Limits

The revised standard introduces additional maximum permissible error limits for pipettes, including separate limits for multichannel pipettes. It provides clarity on the information that manufacturers must provide to users regarding compatible tips and the pipettes' specifications. These limits enable laboratories to have a clearer understanding of the expected performance of their pipettes and make informed decisions about their usage.

Reference Measurement Procedures

ISO 8655:2022 defines two reference measurement procedures for pipette calibration: the gravimetric procedure (Part 6) and the photometric procedure (Part 8). Adhering to strict environmental conditions is crucial when using these reference procedures. However, the standard also allows for alternative measurement procedures (Part 7) within defined limits. These alternative procedures offer some flexibility while maintaining accuracy and precision. To ensure reliability, at least ten replicate measurements per selected volume should be performed and validated against one of the reference procedures.

Changing Pipette Tips During Calibration

To account for potential variations in tip quality, the revised standard requires changing the pipette tip at least once per tested volume during calibration. This ensures that any inconsistencies or deviations in tip performance are captured, resulting in more accurate measurements. Remember to factor this requirement into your pipette calibration process to uphold the highest level of precision.

Balances for Gravimetric Testing

ISO 8655:2022 imposes increased requirements on the balances used for gravimetric testing and calibration. For pipettes with a nominal volume of up to 20 μL, a 6-place balance is now necessary. Similarly, an analytical balance with five places is required for a nominal volume of 200 μL. Multi-channel balances can be employed to calibrate multi-channel pipettes, with each channel's measurement analysed individually. These improved balance specifications ensure reliable weight measurements, a cornerstone of gravimetric calibration.

By adhering to ISO 8655:2022, laboratories, manufacturers, calibration facilities, and users can uphold the quality and accuracy of their pipette operations. Following these updated guidelines will lead to credible analytical data, enabling researchers to make informed decisions and advance scientific knowledge.

In conclusion, understanding and implementing the revised ISO 8655:2022 standard is essential for achieving accurate and reliable pipetting. By considering the impact of pipette tips, adhering to maximum permissible error limits, utilising reference measurement procedures, changing pipette tips during calibration, and using appropriate balances, laboratories can ensure precise and trustworthy results. Embrace the power of ISO 8655:2022 and elevate the quality of your laboratory measurements through meticulous pipette calibration!

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