Overview
ISO 5120:2023 - Soil quality - Determination of perchlorate in soil using liquid chromatography-tandem mass spectrometry (LC‑MS/MS) specifies a trace analytical method for measuring perchlorate (ClO4−) in soil and soil‑like materials. The document covers sample pretreatment (drying, sieving), extraction, clean‑up, LC‑MS/MS analysis, calibration and calculation of perchlorate content on a dry‑weight basis. Under the conditions defined, the method achieves an approximate limit of quantitation (LOQ) of 4.6 μg/kg (dry soil).
Key topics and technical requirements
- Scope and principle: Extraction of perchlorate from pretreated soil using distilled/deionized water, followed by LC‑MS/MS determination.
- Sample pretreatment: Air‑drying and sieving in accordance with general soil sample preparation practices (see ISO 11464).
- Extraction and separation:
- Mechanical shaking and centrifugation to recover perchlorate into aqueous extract.
- Filtration through a 0.2–0.45 μm membrane (e.g., cellulose acetate, hydrophilic polypropylene or polyethersulfone).
- Clean‑up and interference control:
- Spike with internal standard after filtration.
- Use of cartridges or columns to remove interfering anions (sulfate, chloride, bicarbonate), cations or organic matter when necessary.
- LC‑MS/MS analysis:
- Reversed‑phase liquid chromatography with acetonitrile‑based mobile phase.
- Isocratic or gradient elution depending on matrix characteristics.
- Tandem mass spectrometric detection with internal standard calibration.
- Calibration & calculation: Follow ISO 8466‑1 or ISO 8466‑2 for calibration strategy and performance estimation.
- Apparatus & QC: Method lists required equipment (centrifuge, mechanical shaker, filtration devices, clean‑up cartridges, pipettes, LC‑MS/MS) and sets out quality control and reporting requirements.
Practical applications
- Environmental laboratories performing trace‑level perchlorate analysis in soils.
- Military site assessment and monitoring where perchlorate‑containing propellants or munitions may have contaminated soils.
- Contaminated site investigations, remediation verification and risk assessment for groundwater/food‑chain exposure.
- Regulatory agencies and consultants establishing or verifying compliance with local soil and water quality guidelines.
- Research institutions studying perchlorate fate, transport and ecological or human health effects.
Who should use this standard
- Analytical chemists and accredited testing laboratories specializing in environmental contaminants.
- Environmental consultants, remediation contractors and project managers.
- Government regulators and policy makers responsible for soil and groundwater quality.
- Researchers developing or validating trace analytical methods for anions in complex matrices.
Related standards
Keywords: ISO 5120:2023, perchlorate, soil quality, LC‑MS/MS, soil analysis, limit of quantitation, perchlorate contamination, environmental monitoring.
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