ISO 18187:2024

Overview

ISO 18187:2024 specifies a rapid contact test for assessing solid samples (soils and waste materials) by measuring the inhibition of dehydrogenase activity of the bacterium Arthrobacter globiformis using the redox dye resazurin. The miniaturized aerobic suspension assay produces a screening result within 6 hours, enabling fast identification of samples containing water‑soluble or solid‑bound non‑volatile contaminants. The second edition extends the scope to include use for testing chemicals (see Annex C) and updates validity and interference guidance for various waste matrices.

Key topics and technical requirements

• Test principle: inhibition of bacterial dehydrogenase activity reduces conversion of resazurin to resorufin; fluorescence measurement of resorufin indicates activity level.
• Test organism and preparations: use of Arthrobacter globiformis (including freeze‑dried preparations and inoculum procedures described in Annex B).
• Controls and blanks: negative and positive controls, Blank A/B, and defined control substrates (e.g., quartz sand or LUFA standard soils) are required to standardize results.
• Procedure elements: preparation of dilutions, aeration, deactivation, inoculum preparation, incubation and fluorescence measurement; calculation of relative fluorescence and percentage inhibition (ECx).
• Quality and validity criteria: built‑in checks for sensitivity (positive controls), statistical analysis, and interlaboratory variability (results summarized in Annex A).
• Interferences and adaptations: guidance on potential interferences (e.g., plastics, low‑density waste) and suggested methodological alternatives; alternative positive controls (e.g., copper sulfate pentahydrate, 3,5‑dichlorophenol, zinc sulfate heptahydrate) for waste testing.

Applications and users

ISO 18187:2024 is aimed at:

• Environmental laboratories conducting soil quality and waste characterization screenings.
• Contaminated land consultants and remediation teams needing rapid triage of samples.
• Regulators and permit authorities requiring consistent, comparable ecotoxicological screening data.
• Research groups and ecotoxicologists studying bioavailability and biological effects of contaminants. Practical uses include rapid screening for contaminated soils and wastes, pre‑screening before detailed chemical analyses, and evaluating effects of test chemicals following Annex C.

Related standards

Normative references and complementary guidance include:

• ISO 5667‑15 (sampling/preservation of sediments/sludge)
• ISO 18400‑206 (soil sampling for microbiological assessment)
• CEN/TR 15310‑1 (waste sampling guidance)
• EN 14735 (preparation of waste samples for ecotoxicity tests)

Keywords: ISO 18187, soil quality, contact test, Arthrobacter globiformis, dehydrogenase activity, resazurin, rapid soil test, waste ecotoxicity, contamination screening, ECx.