Overview
EN ISO 18724:2025 - Water quality: Determination of dissolved chromium(VI) in water - Photometric method is a CEN-endorsed ISO standard that defines a uniform photometric procedure for measuring dissolved hexavalent chromium (Cr(VI)) in water. The method is based on the well-established reaction with 1,5-diphenylcarbazide (DPC) and covers manual, automated static and automated dynamic photometric techniques, as well as ion chromatography with post‑column reaction (IC‑PCR).
Key topics and technical requirements
- Scope and matrices: Applicable to drinking water, raw water, surface water, cooling water, treated wastewater and aqueous eluates; also applicable to landfill leachates and raw wastewater after appropriate validation.
- Measurement techniques:
- Manual (hand photometry)
- Automated static (discrete analyser systems)
- Automated dynamic (flow injection analysis - FIA, continuous flow analysis - CFA)
- Ion chromatography with post‑column reaction (IC‑PCR)
- Sensitivity and working ranges:
- Coupled techniques (e.g., IC‑PCR) can determine Cr(VI) at low levels down to about 0.02 µg/L.
- Typical static, FIA and CFA techniques are suitable for concentrations ≥ 2 µg/L; using long optical path cuvettes (>100 mm) extends sensitivity below 2 µg/L.
- Standard content: Clauses on interferences, sampling, preservation and storage; procedural steps (reagents, apparatus, calibration, measurement); calculation methods, calibration validity checks, and reporting. Normative annexes provide procedures for manual/static/dynamic techniques and guidance for reagent/flow adjustments; informative annex contains performance data.
- Quality and validation: Requires method validation for non-standard matrices, calibration checks, and consideration of matrix interferences and coloured samples.
Applications and users
- Environmental and drinking-water laboratories performing regulatory compliance testing.
- Wastewater and landfill monitoring teams assessing leachates and treated effluents (after validation).
- Industrial process and QA labs (electroplating, tanning, textile industries) monitoring Cr(VI) discharges.
- Instrument manufacturers and service providers that supply photometers, FIA/CFA systems or IC‑PCR solutions and need to align with recognized test methods.
- Regulators and auditors who require reproducible, standardized measurement procedures for hexavalent chromium in water.
Related standards
Keywords: EN ISO 18724:2025, water quality, chromium(VI), Cr(VI) photometric method, 1,5-diphenylcarbazide, FIA, CFA, IC‑PCR, dissolved chromium(VI), water analysis.
