Overview
ISO 21863:2020 specifies a validated analytical method for the determination of alkylmercury compounds in filtered water samples using gas chromatography–mass spectrometry (GC‑MS) after derivatization by phenylation and solvent extraction. The procedure targets individual methylmercury (MeHg) and ethylmercury (EtHg) in surface water and wastewater and is applicable to concentrations from 0.2 μg/L to 10 μg/L (as mercury mass), with dilution or sample-size adjustment for higher levels. The standard supports water‑quality monitoring and regulatory compliance efforts related to mercury pollution and the Minamata Convention on Mercury.
Key topics and technical requirements
- Scope and matrices: Filtered surface water and wastewater; determination of MeHg and EtHg.
- Derivatization (phenylation): Alkylmercury compounds are phenylated using sodium tetraphenylborate (recommended solution density ~20 g/L) at pH 5.0 (acetate buffer) to form volatile phenylated derivatives suitable for GC.
- Solvent extraction: Liquid–liquid extraction into toluene, dehydration of extracts, and preparation for GC‑MS analysis.
- Instrumental analysis: Gas chromatography coupled with mass spectrometry (GC‑MS) for separation and identification; guidance on optimization, identification, and blank/carry‑over checks.
- Quantification and quality control: Use of an internal standard, calibration (internal standardization), spike‑recovery tests, performance checks, and statistical evaluation of calibration and results.
- Interferences and sampling precautions: Potential interferences from organosulfur compounds (e.g., L‑cysteine), high salt or particulate loads (which may precipitate tetraphenylborate), and GC co‑eluting compounds. Use only fluoropolymer or borosilicate glass containers to prevent mercury loss or contamination.
- Annexes: Informative annexes provide example GC‑MS operating conditions, mass spectra, alternative derivatizing agent (sodium tetrapropylborate), alternative detector (GC‑AFS), and performance data.
Applications and who uses it
- Environmental laboratories performing water quality monitoring for alkylmercury (MeHg/EtHg).
- Regulatory agencies enforcing effluent and environmental standards related to mercury.
- Research institutions studying mercury speciation, biogeochemical cycling, and contaminant transport.
- Industrial facilities tracking wastewater discharges to meet best‑available‑techniques and compliance obligations under the Minamata Convention.
Keywords: ISO 21863:2020, alkylmercury, methylmercury, ethylmercury, GC‑MS, phenylation, solvent extraction, water quality, wastewater analysis, mercury speciation.
Related standards
- ISO 3696 (water for analytical laboratory use)
- ISO 5667 series (water sampling and preservation)
- ISO 8466‑1 (calibration and evaluation of analytical methods)
Open preview (PDF)Water quality — Determination of alkylmercury compounds in water — Method using gas chromatography-mass spectrometry (GC-MS) after phenylation and solvent extraction