Comparative Analysis of ISO 8655-2:2002 vs. ISO 8655-2:2022
Introduction
Pipettes are essential piston-operated volumetric apparatus (POVA) widely used in laboratories for accurate liquid handling. To ensure reliability and comparability across laboratories, ISO introduced the ISO 8655 series, which defines terminology, metrological requirements, and test methods for piston-operated apparatus.
Part 2 of the series — ISO 8655-2 — specifically addresses pipettes. First published in 2002 and revised in 2022, the standard has undergone significant updates to reflect changes in laboratory practice, calibration technology, and regulatory needs.
This article provides a clause-by-clause comparison between ISO 8655-2:2002 and ISO 8655-2:2022, highlighting key changes that calibration laboratories, manufacturers, and QA/QC departments need to consider.
Scope of Both Editions
- 2002 edition: Titled Piston pipettes, focusing on piston-operated air-displacement and positive-displacement pipettes.
- 2022 edition: Titled simply Pipettes, making the scope broader and aligning terminology with other parts of the ISO 8655 series.
Both editions cover:
- Metrological requirements
- Maximum permissible errors
- Marking requirements
- User information
However, the 2022 edition significantly expands requirements for adjustment, pipette tips, error calculation, and electronic pipettes.
Clause-by-Clause Comparison
Below is a structured comparison of the two editions:
| Section / Topic | ISO 8655-2:2002 | ISO 8655-2:2022 | Main Changes |
| Title | Piston pipettes | Pipettes (air & positive displacement) | Broader scope. |
| Normative References | ISO 3696, ISO 8655-1:2002, ISO 8655-6:2002 | ISO 3696:1987, ISO 8655-1, 8655-6:2022, + ISO 8655-7, 8655-8 | New references for alternative & photometric methods. |
| Adjustment | Manufacturer initial setting at 20 °C (27 °C optional); user adjustment only via ISO 8655-6. | Initial + subsequent adjustment; may use ISO 8655-6, 7, or 8; mandatory marking of re-adjustments; stricter rules for liquids other than water. | Stronger adjustment & documentation requirements. |
| Design | Types A & D; D1/D2 defined; hand warmth negligible. | Same types; explicit note that hand warmth causes systematic drift. | Clearer requirement to minimize thermal effects. |
| Pipette Tips | General requirements for orifice shape, sterilization, and alignment. | Expanded details; sterilisability; dimensional tolerances; batch validation required (Clause 9.7). | Stricter quality control for tips. |
| Metrological Performance | Two tables: A & D1 (single-channel), D2; multi-channel = 2× single-channel; intermediate volumes = next higher nominal. | Three tables: A & D1 (single-channel), A & D1 (multi-channel), D2. New formula (9.6) for intermediate volumes; errors capped at 25%; volumes <10% volumes not valid. | Complete restructuring with new calculation rules. |
| User Information | Annex A: The supplier provides information on volumes, tips, and sterilization. | Clause 10: Expanded list (adjustment basis, recommended tips, error limits, cleaning, chemical compatibility, storage, etc.). | Much broader obligations for manufacturers. |
| Marking | Nominal volume, unit, brand, type; serial no. Optional. | Mandatory: volume/range, unit, brand, type, serial no.; recommended: “Ex” + reference temperature. | Stricter marking requirements. |
| Annexes | Annex A (normative): Info for users; Annex B (informative): Error sources. | Annex A (informative): Error sources; Annex B (informative): New – motorized pipettes & multi-dispense testing. | New annex for electronic pipettes. |
Key Takeaways for Laboratories and Manufacturers
- Adjustment & Documentation
- Labs must ensure adjustment is traceable and documented, especially when re-adjusting for liquids other than water.
- Error Calculation
- The 2022 edition introduces a formula-based approach for intermediate volumes, replacing the older “next higher nominal” rule.
- Pipette Tips
- Validation of pipette tips (including batch and mould variations) is now mandatory. This affects both manufacturers and calibration labs.
- Electronic Pipettes
- A new Annex B addresses motorized pipettes and multi-dispensing, reflecting their increasing use in modern labs.
- User Information & Marking
- Manufacturers must now provide more detailed user information and stricter markings on instruments.
Conclusion
The revision of ISO 8655-2 in 2022 represents a major step toward more reliable and consistent pipette calibration worldwide. Laboratories and manufacturers should review their SOPs, calibration protocols, and quality documentation to ensure alignment with the updated standard.
For a detailed Excel and PDF version of the clause-by-clause comparison, including numerical tables, you can access our prepared resources here:
