Overview
ISO/TS 16727:2013 specifies a laboratory procedure for the determination of mercury in sludge, treated biowaste and soil using cold vapour atomic fluorescence spectrometry (CVAFS / CV-AFS). The method applies to mercury measured in aqua regia or nitric acid digests prepared according to ISO 11466 or ISO 16729. The stated lower working range limit is 0.003 mg/kg (dry matter). The technique relies on chemical reduction of Hg to elemental vapor, carrier gas transport into an atomic fluorescence spectrometer and quantification via a calibration curve.
Key topics and technical requirements
- Sample matrices: Digests from soil, sludge and treated biowaste (ISO 11466 / ISO 16729).
- Detection method: Cold vapour atomic fluorescence spectrometry (Hg excitation around 254 nm; photomultiplier detection).
- Reduction reagents: Tin(II)-chloride recommended; sodium borohydride may be used but can introduce additional interferences.
- Carrier gas and gas purity: Argon or nitrogen; argon preferred for higher sensitivity; argon ≥ 99.99% recommended.
- Calibration and quantitation: Use mercury standard solutions to prepare a multi-point calibration covering the measurement range; blank and test-blank procedures are required.
- Working range examples: Direct determination for ~0.1–10 µg/L in digest (equivalent to ~0.003–0.3 µg/g for a 3.0 g sample); sensitivity may be increased by amalgamation or automated flow systems.
- Interferences: Water vapour/aerosols (quenching), noble metals (gold, silver-amalgamation), anions that complex Hg (sulfide, iodide, bromide); recommended mitigation includes drying carrier gas and choice of reducing agent.
- Apparatus: Clean laboratory glassware, atomic fluorescence spectrometer with Hg lamp and 254 nm filter, cold-vapour generator (batch or automated FIA/flow injection), optional automated sample introduction for ultra-trace sensitivity.
Applications and users
- Environmental laboratories performing soil quality assessments, contamination surveys and regulatory compliance testing for mercury.
- Waste and sludge testing facilities evaluating mercury in treated biowaste or sludges destined for land application or disposal.
- Research labs conducting trace/ultra-trace mercury analyses in digested environmental samples.
- Quality managers and technical staff responsible for method validation, instrument setup, calibration and interference control.
Related standards
- ISO 11466 - Extraction of trace elements soluble in aqua regia
- ISO 16729 - Digestion of nitric acid soluble fractions of elements
- ISO 11465 - Determination of dry matter and water content
- ISO 3696 - Water for analytical laboratory use
Keywords: ISO/TS 16727:2013, cold vapour atomic fluorescence spectrometry, CVAFS, mercury determination, soil quality, aqua regia digest, nitric acid digest, tin(II)-chloride, flow injection analysis.