Overview
ISO/TR 22814:2020 - Good practice for dynamic light scattering (DLS) measurements - is a technical report that provides practical, application-focused guidance for performing and interpreting DLS measurements. It complements ISO 22412:2017 by going beyond artefact treatment to cover experiment planning, sample information gathering, sample preparation, instrument verification, data‑quality assessment and interpretation for solids, emulsions and bubbles. The emphasis is on actionable steps to obtain reliable DLS results rather than on theory.
Key topics and requirements
- Instrument types & optics: Guidance for different configurations (e.g. homodyne correlation and heterodyne frequency‑spectrum approaches) and the influence of scattering angle on measurement reliability.
- Pre‑analysis information: Recommended sample metadata to collect - composition, coating, density, refractive index, viscosity, colloidal stability, concentration and expected polydispersity - to inform experiment design and uncertainty.
- Sample preparation: Practical advice on dispersion, dilution, filtration, handling of coloured samples, avoidance of air bubbles, and cuvette cleanliness to reduce spurious scattering.
- Instrument verification: Steps for verifying instrument function, including operation qualification and routine checks to ensure consistent performance.
- Data quality & interpretation:
- Correlation analysis: Interpretation of correlograms and guidance on judging data quality.
- Frequency power spectrum analysis: Considerations for precision, run time and sample quality.
- Conversion issues: Caveats when converting intensity‑weighted data to volume or number distributions and when using cumulants (e.g. z‑average) versus distribution‑based analyses.
- Method robustness and ruggedness: How to investigate and document robustness of the DLS method under varying conditions.
Practical applications and users
ISO/TR 22814 is intended for:
- Analytical laboratories and instrument operators performing particle size and hydrodynamic diameter measurements.
- Quality control (QC) teams in pharmaceuticals, biotechnology, cosmetics and materials manufacturing who use DLS for batch release or stability testing.
- Researchers in colloid science, nanomaterials, emulsions and bubble studies who need guidance on experimental design and data interpretation.
- Laboratories deciding whether DLS is the appropriate technique for a given sample or whether alternative techniques (e.g. laser diffraction) are required.
Typical use cases:
- Planning DLS experiments for suspensions, emulsions or foams.
- Preparing samples to avoid aggregation, sedimentation or contamination.
- Verifying instrument performance and assessing measurement uncertainty.
- Interpreting correlograms, size distributions and converting results appropriately.
Related standards
- ISO 22412:2017 - Particle size analysis - Dynamic light scattering (DLS) - provides theoretical background and artefact treatment; ISO/TR 22814:2020 offers complementary practical good practice.
For the official document and purchase, see the ISO website (www.iso.org).