Overview
ISO 20295:2018 specifies a standardized laboratory method for the determination of perchlorate in soil and soil materials using ion chromatography (IC). The method detects perchlorate at concentrations as low as 0.1 mg/kg under the conditions described. The working measurement range depends on the ion‑exchange capacity of the chosen separator column; dilution of aqueous soil extracts may be required to bring samples into range.
Key topics and technical requirements
- Sample preparation: dry and sieve soil; extract perchlorate with distilled or deionised water by mechanical shaking and centrifugation; filter extracts through a 0.45 μm membrane (e.g., cellulose acetate, polypropylene, PES).
- Separation and detection: use high‑capacity anion‑exchange separator columns with suppressed conductivity detection (CD). Columns must tolerate injection volumes up to 1 mL.
- Eluents: commonly used eluents include carbonate, hydrogen carbonate, hydroxide solutions and may be modified with organic solvents (acetone, acetonitrile). Eluents must be degassed and chosen to meet resolution requirements for perchlorate.
- Interferences and mitigation:
- High concentrations of chloride, sulfate, carbonate, metals (Fe, Al), or phosphate species can affect perchlorate recovery or IC performance.
- Mitigation options: sample dilution, selective removal using cartridges or cation‑exchange resins (Na‑, Ag‑, Ba‑, H‑forms), pre‑columns, inline matrix elimination, re‑injection techniques or two‑dimensional IC (Annexes C–E).
- Quality control and calibration:
- Calibrate and evaluate the analytical procedure per ISO 8466‑1 or ISO 8466‑2.
- Check separator column performance and validity of the calibration function; use replicate determinations and standard addition when matrix effects are suspected.
- Documentation: report results, calibration checks and any pre‑treatment steps as specified in the standard.
Practical applications and users
ISO 20295 is aimed at laboratories and professionals involved in:
- Environmental testing and soil quality monitoring for perchlorate contamination
- Contaminated site assessment and remediation (e.g., firing ranges, military impact areas, industrial sites)
- Regulatory compliance and environmental surveillance programs
- Research on perchlorate fate, transport and uptake in soils and vegetation
This method supports accurate, comparable perchlorate measurements in soils where water‑soluble anions are of concern and where IC provides the required sensitivity and selectivity.
Related standards
- ISO 8466‑1: Statistical evaluation of linear calibration functions (normative for calibration).
- ISO 8466‑2: Calibration strategy for non‑linear second‑order calibration functions.
Keywords: ISO 20295, perchlorate in soil, ion chromatography, soil quality standard, perchlorate determination, suppressed conductivity, soil testing, environmental laboratory.