ISO 24384:2024
Water quality
- Standard No.
- ISO 24384:2024
- Release Date
- 2024
- Published By
- International Organization for Standardization (ISO) IX / ISO
- Latest
- ISO 24384:2024
- Introduction
Analysis of the core content of the standard
ISO 24384:2024 has established for the first time an international standard method for the determination of chromium forms in water using LC-ICP-MS coupling technology. Its technological breakthroughs are reflected in:
Technical parameters PDCA chelation method EDTA chelation method Pretreatment temperature 80±3℃ 70±3℃ Reaction time 30 minutes 60 minutes Detection limit (52Cr) 0.012-0.044μg/L 0.022-0.030μg/L Applicable water sample types Drinking water/surface water/wastewater (0.2-500μg/L)
Method principle and technical evolution
The standard uses 2,6-pyridinedicarboxylic acid (PDCA) or ethylenediaminetetraacetic acid (EDTA) chelation pretreatment to uniformly convert unstable Cr(III) forms in water samples into stable complexes:
- pH is accurately adjusted to 6.9±0.1
- Forming Cr(III)-PDCA/EDTA complex
- LC separation followed by ICP-MS detection (monitoring 52Cr and 53Cr isotopes)
Compared with conventional spectrophotometry, this method reduces the detection limit of Cr(VI)/Cr(III) by more than 10 times and avoids errors caused by redox conversion.
Control of key interference factors
Typical interference case:
When >100mg/L transition metals (such as Co²⁺, Ni²⁺) are present in water samples, they will compete with chelating agents, resulting in low Cr(III) determination values. The standard recommends:
- Sample dilution (maximum dilution ratio 1:10)
- Spike recovery verification (required 80-120%)
- Total chromium calibration (difference ≤30%)
Implementation recommendations
Based on the verification data of laboratories in 11 countries (Table C1/C2), it is recommended to give priority to the PDCA chelation scheme:
Indicators PDCA method EDTA method Cr(VI) recovery 96-102% 88-96% Inter-laboratory deviation ≤7.3% ≤20% Operation points: Use PEEK connecting tubes (inner diameter <0.25mm), verify the calibration curve daily, and store samples in a dark and refrigerated place (3±2℃).
ISO 24384:2024 Referenced Document
- ISO 8466-1 Water quality — Calibration and evaluation of analytical methods — Part 1: Linear calibration function
ISO 24384:2024 history
- 2024 ISO 24384:2024 Water quality
