Overview
ISO 24421:2023 - Biotechnology - Minimum requirements for optical signal measurements in photometric methods for biological samples - provides a general framework of minimum requirements to support accurate optical signal measurements in photometric methods. It covers measurement types such as bioluminescence, chemiluminescence, fluorescence and absorption and addresses verification of optical-signal measurement instruments and the use of optical references (e.g., LED‑based reference light sources, calibrated power meters). The standard is intended to improve repeatability, intermediate precision and reproducibility of optical measurements used for qualitative and quantitative characterization of biological samples.
Key topics and technical requirements
- Scope and principles: Defines terms (optical signal, dynamic range, precision, accuracy) and gives general measurement principles for photometric methods.
- Instrument verification: Minimum requirements for verifying optical-signal measurement instruments (e.g., luminometers, fluorescence plate readers, flow cytometers) including procedures and examples in informative annexes.
- Optical references and reference light sources: Guidance on selection, use and characterization of optical references to compare measurements across instruments, labs and manufacturers.
- Dynamic range and background signals: Requirements to determine and report instrument dynamic range and to assess background/blank signals that affect quantitative results.
- Calibration curve and quantitative measurement: Minimum expectations for constructing and using calibration curves and for establishing quantitative measurement capability.
- Data analysis and reporting: Guidance on data treatment, reporting of measurement conditions and performance monitoring to support reproducible results.
- Personnel and method considerations: Notes on competence and procedural elements needed to ensure reliable photometric measurements.
- Informative annexes: Practical examples (qualification of luminometers, well-to-well crosstalk, calibration examples, spectral properties) to aid implementation.
Practical applications and intended users
ISO 24421:2023 is applicable across biotechnology, life sciences and medical laboratories where photometric methods are used, including:
- Instrument manufacturers (design and verification of luminometers, plate readers, flow cytometers)
- Laboratory managers and quality assurance personnel implementing instrument qualification and ongoing performance monitoring
- Method developers validating photometric assays (bioluminescence, fluorescence, absorption)
- Regulatory and accreditation bodies assessing measurement practices
- Researchers and biomanufacturing teams needing consistent optical-signal measurement for drug development, toxicity testing, regenerative medicine, biobanking and environmental risk assessment
Note: ISO 24421 provides general minimum requirements and does not replace sector‑ or application‑specific performance criteria; users should consult relevant domain standards when applicable.
Related standards
The document references terminology databases and includes a bibliography and annex listing representative photometric methods and relevant standards to consult for application‑specific guidance.