ISO 13319-1:2021

Overview

ISO 13319-1:2021 - Determination of particle size distribution - Electrical sensing zone method - Part 1: Aperture/orifice tube method specifies a standardized procedure for measuring particle size distributions of particles dispersed in an electrolyte using the electrical sensing zone (ESZ) technique. The method records electrical impedance pulses as particles traverse an aperture; pulse height is treated as proportional to particle volume and converted to a volume‑equivalent diameter. The technique is applicable (implementation dependent) from about 0.5 μm up to above 1 mm and covers a broad range of materials including biologics (cells) and industrial powders (carbon, cement, ceramics, metals, pigments, polymers).

Key topics and technical requirements

• Principle and instrumentation: aperture/orifice in an insulating wall, electrodes, amplifier, pulse-height analysis and counting.
• Measurement fundamentals: pulse-height ↔ particle volume relationship; analysis volume and size binning.
• Operational controls:
  • selection and preparation of the electrolyte solution
  • choice of aperture(s) and analysis volume for the intended size range
  • sample dispersion, stirring and methods for low‑density or paste samples
  • procedures for clearing aperture blockages and maintaining dispersion stability
• Performance considerations:
  • dead time and limits on the maximum count to avoid coincident passage
  • instrument linearity (aperture/amplifier and counting system)
  • repeatability and reproducibility of counts and method precision
• Calibration and quality assurance:
  • microsphere (traceable) calibration procedures and calibration of frequently used apertures
  • instrument qualification, required reporting parameters and verification tests (e.g., chi‑squared)
• Informative annexes: method development aids (fishbone diagram), mass integration for calibration, porous/conductive particle calibration, multi‑aperture techniques.

Applications and users

ISO 13319-1:2021 is used by:

• QC/analytical laboratories in pharmaceuticals, biologics and medical-device testing (particle counts in suspensions)
• Material science and process control teams in ceramics, metal powders, pigments and polymer production
• Environmental and research labs performing particle size analysis where electrolyte‑based measurement is appropriate
• Instrument manufacturers and method developers for ESZ instruments seeking standardized calibration and reporting practices

Practical benefits include standardized calibration methods, improved comparability of particle size distributions, and guidance to minimize counting errors (coincidence, dead time) for robust quality control.

Related standards

• Part of the ISO 13319 series (consult ISO website for additional parts). For implementation, refer to national accreditation and laboratory validation guidance when applying this standard in regulated industries.