ISO 21501-1-2009 PDF

Full title and description

ISO 21501-1:2009 — Determination of particle size distribution — Single particle light interaction methods — Part 1: Light scattering aerosol spectrometer. This international standard specifies the characteristics and performance requirements of a light scattering aerosol spectrometer (LSAS) used for single-particle measurement of aerodynamic/optical size, number concentration and number-based size distribution of particles suspended in a gas.

Abstract

ISO 21501-1:2009 defines the operational scope and measurable characteristics for light scattering aerosol spectrometers (LSAS). It covers the single-particle light-scattering technique for size measurement (typical sizing range ≈ 0.06 µm to 45 µm), required performance parameters (sizing accuracy, size resolution, counting efficiency), and typical maximum concentrations for which the instruments are intended. The standard lists typical application areas including pharmaceutical inhaler testing, filter/separator evaluation and environmental aerosol monitoring.

General information

• Status: Withdrawn (superseded by a later edition).
• Publication date: June 2009 (2009-06).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 19.120 (Particle size analysis).
• Edition / version: Edition 1 (2009).
• Number of pages: 27 (original publication).

Scope

This part of ISO 21501 specifies characteristics of a light scattering aerosol spectrometer (LSAS) for measuring particle size, number concentration and number/size distribution by single-particle light scattering. The method is intended for particles in the approximate diameter range 0.06 µm to 45 µm and for relatively high particle concentrations (instruments conforming to the standard are applicable up to about 1×10¹¹ particles·m⁻³). The standard is intended for instrument performance definition, testing and reporting in applications such as pharmaceutical inhaler characterization, filter and separator cut-off determination, and environmental aerosol measurements.

Key topics and requirements

• Definition of LSAS functional characteristics and required performance metrics (sizing accuracy, size resolution, counting efficiency).
• Declared measurement size range (approximately 0.06 µm to 45 µm).
• Maximum recommended particle number concentration and handling of high concentrations.
• Requirements for reporting particle number/size distributions and associated uncertainties.
• Application-specific performance expectations (pharmaceutical aerosols, filter/separator testing, environmental monitoring).

Typical use and users

Primary users include instrument manufacturers (design and conformance testing), calibration and test laboratories, pharmaceutical development and quality-control teams (MDI, DPI, nebulizer testing), environmental and occupational aerosol researchers, and organisations performing filter and separator efficiency testing. The standard serves as a reference for specifying instrument capabilities, performing acceptance tests and reporting measurement results.

Related standards

ISO 21501 is a multipart series addressing single-particle light interaction methods. Related parts and revisions include ISO 21501-2 (light scattering liquid-borne particle counter) and ISO 21501-3 (light extinction liquid-borne particle counter), both revised in 2019, and later revisions/editions of part 1 (ISO 21501-1:2025 replaces the 2009 edition). These related parts cover calibration, verification and test methods for liquid-borne counters and other techniques within the same series.

Keywords

particle size distribution, light scattering, aerosol spectrometer, LSAS, single-particle, sizing accuracy, size resolution, counting efficiency, aerosol measurement, inhaler testing, filter efficiency.

FAQ

Q: What is this standard?

A: ISO 21501-1:2009 is an international standard that defines the characteristics and performance requirements for light scattering aerosol spectrometers (LSAS) used to measure particle size and number-based size distributions by single-particle light scattering.

Q: What does it cover?

A: It covers instrument characteristics, the intended particle size range (≈ 0.06 µm to 45 µm), performance metrics (sizing accuracy, size resolution, counting efficiency), and application contexts such as pharmaceutical aerosol testing, filter/separator evaluation and environmental aerosol measurements.

Q: Who typically uses it?

A: Instrument manufacturers, calibration and test laboratories, pharmaceutical quality and R&D groups, environmental and occupational aerosol researchers, and organisations conducting filter or separator performance testing.

Q: Is it current or superseded?

A: ISO 21501-1:2009 has been withdrawn and superseded by a later edition — ISO 21501-1:2025 (published as the revised edition). For current requirements and any added calibration/validation procedures, refer to the 2025 edition.

Q: Is it part of a series?

A: Yes — ISO 21501 is a multipart series of standards for single-particle light interaction methods. Other parts (for example ISO 21501-2 and ISO 21501-3) address liquid-borne particle counters and have been updated in subsequent editions.

Q: What are the key keywords?

A: particle size distribution; light scattering; aerosol spectrometer; LSAS; single-particle counting; sizing accuracy; counting efficiency; inhaler testing; filter efficiency.