Overview
ISO 16772:2004 specifies a laboratory method for the determination of mercury (Hg) in soil using an aqua regia extract and measurement by cold‑vapour atomic absorption spectrometry (CV‑AAS) or cold‑vapour atomic fluorescence spectrometry (CV‑AFS). The procedure applies to soil extracts prepared in accordance with ISO 11464 and ISO 11466 and gives a limit of determination of at least 0.1 mg/kg (dry matter). The standard includes safety warnings (mercury is highly toxic) and quality control expectations for trace analysis.
Key Topics and Requirements
- Scope: Measurement of Hg in aqua regia soil extracts using CV‑AAS or CV‑AFS; LOD ≥ 0.1 mg/kg.
- Analytical principle: Mercury in solution is reduced to elemental vapour (tin(II) chloride specified) and measured either by absorbance at 253.7 nm (CV‑AAS) or by atomic fluorescence (CV‑AFS).
- Reagents & gases: aqua regia, nitric and hydrochloric acids, tin(II) chloride as reductant, certified mercury standards, and high‑purity argon or nitrogen (argon recommended for AFS).
- Apparatus: properly equipped AAS or AFS, cold‑vapour generator (manual batch or automated FIAS), appropriate cells (heated silica cell for AAS), and clean labware for trace analysis.
- Calibration & blanks: multi‑point calibration from prepared mercury standards; routine blank determinations and diluted aqua regia matrix matching.
- Matrix checks: mandatory use of the standard addition method at least once per soil type to detect matrix interferences; switch to standard additions if calibration and addition results differ.
- Quality control: use of certified reference materials (CRM), control charts, and documented in‑house reference materials to ensure traceability and stability.
- Safety: strict handling procedures to avoid mercury exposure and environmental release.
Applications
- Environmental monitoring of mercury contamination in soils (industrial sites, mining, agricultural inputs).
- Baseline surveys and post‑remediation verification for contaminated land projects.
- Regulatory compliance testing where soil mercury concentrations must be quantified.
- Routine laboratory testing in environmental and geochemical laboratories using CV‑AAS or CV‑AFS.
Who Uses This Standard
- Environmental testing laboratories and accredited analytical facilities
- Soil scientists and geochemists conducting trace element surveys
- Remediation contractors and environmental consultants
- Regulatory agencies and monitoring networks assessing soil quality
Related Standards
- ISO 11466 - Extraction of trace elements soluble in aqua regia
- ISO 11464 - Pretreatment of soil samples for physico‑chemical analysis
- ISO 11465 - Determination of dry matter and water content (gravimetric)
- ISO 3696 - Water for analytical laboratory use
Keywords: ISO 16772, mercury determination, soil quality, aqua regia extract, cold‑vapour AAS, CV‑AFS, CV‑AAS, tin(II) chloride, mercury in soil, environmental monitoring.