Overview
ISO 24384:2024 specifies a laboratory method for the speciation and quantification of chromium in water: chromium(VI) [Cr(VI)] and chromium(III) [Cr(III)]. The procedure uses liquid chromatography coupled with inductively coupled plasma mass spectrometry (LC‑ICP‑MS) after a chelation pretreatment (PDCA or EDTA) and is applicable to wastewater, surface water, groundwater, and drinking water. The standard covers dissolved Cr species in the working range 0.20 μg/L to 500 μg/L (as Cr mass); samples with higher concentrations can be measured after appropriate dilution.
Key technical topics and requirements
- Principle: Convert varied Cr(III) species into a stable Cr(III)-chelate (PDCA or EDTA) at an adjusted sample pH of 6.9 ± 0.1, then separate Cr(VI) and the Cr(III)-chelate by LC and detect with ICP‑MS.
- Analytical range: 0.20–500 μg/L per species; dilution allowed for higher concentrations.
- Sample handling: Emphasizes careful sampling, preservation, labware cleaning and avoidance of contamination or unintended redox reactions during storage and preparation.
- Interferences:
- Reductants (e.g., Fe2+, ascorbic acid) and oxidants or high organic loads can shift Cr redox balance and bias results.
- High concentrations of other metal cations or complexing agents can suppress chelation and reduce Cr(III) recovery.
- Polyatomic ions formed in ICP (e.g., ArC+, ClO+) can interfere at m/z 52 and 53; mitigation includes collision‑reaction cells, chromatographic separation, or high‑resolution/tandem MS.
- The sum of Cr(VI) + Cr(III) should match total Cr (ICP‑MS) within ≤ 30%; larger discrepancies indicate interference.
- Quality control: Calibration across the full procedure, blank measurements, and recovery tests to evaluate chelation efficiency and matrix effects.
- Annexes: Examples of LC‑ICP‑MS operating conditions for PDCA and EDTA pretreatments and performance data.
Practical applications and who uses it
ISO 24384:2024 is designed for:
- Environmental and public‑health laboratories conducting Cr speciation for regulatory compliance and risk assessment.
- Water utilities and wastewater treatment facilities monitoring effluents and drinking water safety.
- Industrial testing (plating, surface finishing, chemical manufacturing) to verify substitution of Cr(VI) by Cr(III).
- Research laboratories studying chromium biogeochemistry and redox behavior.
Typical users: analytical chemists, laboratory managers, environmental agencies, contract testing labs, and instrument vendors offering LC‑ICP‑MS solutions.
Related standards and keywords
- Related normative reference: ISO 8466‑1 (calibration and evaluation of analytical methods).
- SEO keywords: ISO 24384:2024, LC‑ICP‑MS chromium speciation, Cr(VI) determination, Cr(III) determination, chelation pretreatment (PDCA, EDTA), water quality testing, environmental monitoring, wastewater analysis, drinking water safety.
This standard provides a robust, validated framework for chromium speciation in water, helping laboratories produce reliable Cr(VI) and Cr(III) data for regulatory monitoring and environmental risk assessment.