Overview
ISO 15913:2000 specifies a validated laboratory method for the determination of selected phenoxyalkanoic herbicides (and related compounds such as bentazones and hydroxybenzonitriles) in ground and drinking water. The procedure targets low mass concentrations (≥ 50 ng/l - see Annex A) and combines solid phase extraction (SPE), derivatization with diazomethane, and analysis by gas chromatography–mass spectrometry (GC‑MS).
Key example analytes include 2,4‑D, mecoprop (MCPP), dichlorprop, MCPA, MCPB, 2,4,5‑T, bentazone, bromoxynil, 2,4‑DB and fenoprop; Annex B lists other substances that may be covered after verification.
Important safety note: diazomethane is highly toxic and potentially explosive; the standard includes specific warnings and handling instructions.
Key topics and technical requirements
- Analytical principle: Acidify sample → enrich analytes on reversed‑phase SPE (e.g., RP‑C18) → elute → methylate acids with diazomethane → analyze methyl esters by GC‑MS.
- Sensitivity: Designed for mass concentrations around 50 ng/l (detailed performance and interlaboratory results in Annex A).
- Sample handling: Follow ISO 5667 series for sampling, preservation and handling to avoid contamination and interferences.
- Reagents and materials: High‑purity solvents and gases, validated SPE cartridges (batch consistency important), internal standards (deuterated or 13C‑labelled preferred), and certified reference solutions for methyl esters and free acids.
- Apparatus: Non‑discriminating GC injection, capillary columns compatible with target analytes, MS detector, glassware for diazomethane generation (or commercial alternatives), filtration options for turbid samples.
- Quality control: Regular recovery checks, calibration with working standards, blank checks, and verification when applying the method to other matrices or additional compounds.
- Interferences: Potential from matrix components or differing SPE batches; hydrolyzable esters may require sample hydrolysis (Annex C); mass spectra provided in Annex D aid identification.
Applications and users
- Water‑testing laboratories performing regulatory monitoring of drinking water and groundwater for herbicide residues.
- Environmental chemistry and public‑health labs conducting pesticide monitoring, compliance testing, or research on phenoxyalkanoic herbicide occurrence.
- Regulatory agencies, utilities, and contract laboratories needing a standard GC‑MS SPE workflow for low‑level herbicide quantification.
- Method developers who need validation references, mass spectra, and interlaboratory precision data.
Related standards
Keywords: ISO 15913, phenoxyalkanoic herbicides, water quality, solid phase extraction, diazomethane derivatization, GC‑MS, bentazone, 2,4‑D, drinking water analysis, pesticide monitoring.