ISO 23909:2008

Overview

ISO 23909:2008 - Soil quality - Preparation of laboratory samples from large samples - defines how to prepare representative laboratory samples from large bulk soil samples (typically up to 25 kg, and applicable to larger samples). The standard links field sampling of large volumes with laboratory pretreatment and analysis workflows used for physico‑chemical parameters, moderately volatile organic contaminants, and non‑volatile contaminants. It explicitly excludes procedures for analysing volatile organic compounds.

Key topics and requirements

• Scope and purpose: Convert large field samples into representative laboratory samples suitable for subsequent analyses described in ISO 11464, ISO 14507 and ISO 16720.
• Representativity: Minimum subsample mass depends on the maximum particle (macro‑aggregate) size (see Annex A). The standard emphasizes maintaining sample integrity and representativity during mixing, division and size reduction.
• Methods of sample division: Approved techniques to obtain a ~1 kg laboratory sample include:
  • Coning and quartering
  • Riffling (riffle boxes)
  • Tyler divider
  • Rotating divider
• Size reduction: If particle size is too large, staged crushing (stone crusher or similar) may be required before final reduction to <2 mm - only when this will not alter the analytes of interest (e.g., avoid heat generation that causes loss of moderately volatile organics).
• Handling and contamination risks: Guidance on avoiding contamination, loss of moisture or volatiles, abrasion and oxidation during pretreatment. The apparatus and location must be clean and suitable for the intended analyses.
• Mechanical vs manual subsampling: Mechanical division is preferred for dry, free‑flowing material; manual methods are often better for cohesive soils. Drying before division is allowed only if it does not affect analyte integrity.
• Reporting: If representative subsamples cannot be produced (e.g., particle size too large), this must be reported and results considered indicative.

Applications

• Environmental laboratories preparing soil for chemical analysis, site assessments, remediation monitoring and quality control.
• Field sampling teams and laboratory technicians linking large composite or stockpile samples to routine lab test sizes.
• Projects analysing physico‑chemical soil parameters, moderately volatile organic contaminants (e.g., PAHs, PCBs) and non‑volatile contaminants where representative subsampling from large samples is critical.

Related standards

• ISO 11464 - Pretreatment of samples for physico‑chemical analysis
• ISO 14507:2003 - Pretreatment for organic contaminants
• ISO 16720 - Pretreatment by freeze‑drying
• ISO 10381‑8:2006 - Sampling guidance for stockpiles

Keywords: ISO 23909:2008, soil quality, sample preparation, laboratory samples, large samples, sample division, coning and quartering, riffle box, particle‑size reduction, moderately volatile organic contaminants.