ISO 5120:2023

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

• ISO 11464 - Soil sample pretreatment guidance.
• ISO 8466‑1 / ISO 8466‑2 - Calibration and evaluation of analytical methods.

Keywords: ISO 5120:2023, perchlorate, soil quality, LC‑MS/MS, soil analysis, limit of quantitation, perchlorate contamination, environmental monitoring.