ISO 8655-8:2022

Overview

ISO 8655-8:2022 specifies a photometric reference measurement procedure for the determination of delivered volume from piston-operated volumetric apparatus (POVA). The procedure covers complete systems - the basic apparatus and any selected disposable or reusable parts - with a maximum nominal volume of 5 000 µl, using a photometric (spectrophotometric) method to measure delivered liquid by delivery (Ex). It is part of the ISO 8655 series for piston-operated volumetric apparatus.

Key topics and requirements

• Scope and applicability: Procedure applies to complete POVA systems (pipettes, dispensers, syringes, burettes as relevant) up to 5 000 µl and includes all parts used during delivery.
• Test equipment: Specifies equipment such as spectrophotometers, cuvettes and mixers, measuring devices, balances, density meters and pH meters required for photometric volume determination.
• Reagents and solutions: Identifies required reagents (e.g., buffer, Ponceau S, copper(II) chloride) and calibrator solutions and addresses solution stability, light sensitivity and storage.
• Test conditions: Defines environmental and procedural test conditions (test room, evaporation control) to ensure repeatable photometric results.
• Procedures:
  • System calibration and calibration-constant determination.
  • Photometric procedure including cuvette preparation, spectrophotometer zeroing, dispensing test liquids and measuring absorbance.
  • Specific test cycles for various device types (single- and multi-channel pipettes, positive-displacement pipettes, burettes, dispensers, syringes) in accordance with related ISO 8655 parts.
• Evaluation and reporting: Calculation of delivered volume, temperature correction, mean volume, systematic and random error analysis, and measurement uncertainty. Reporting requirements and referencing normative annexes (e.g., balance-based volume calculations).

Applications and users

• Calibration laboratories and test houses seeking a traceable, high-precision method for volumetric calibration using photometry.
• Manufacturers of pipettes and piston-operated devices for quality control and declaration of performance.
• Laboratory quality managers and users who require validated calibration methods for routine verification and instrument qualification.
• Useful in regulated environments (e.g., clinical, pharmaceutical, research) where accurate micro-volume delivery (µl range) must be demonstrated.

Related standards

• ISO 8655 series (Part 1 general requirements; Part 2 pipettes; Part 3 burettes; Part 5 dispensers; Part 9 syringes)
• ISO 1042 (volumetric flasks) and ISO 3696 (water for analytical use)
• ISO/IEC Guide 99 (VIM) for metrology vocabulary

Keywords: ISO 8655-8:2022, photometric reference measurement procedure, piston-operated volumetric apparatus, pipette calibration, spectrophotometric volume determination, measurement uncertainty.