ISO 15061:2001

Overview

ISO 15061:2001 defines a standardized laboratory method for the determination of dissolved bromate in water by ion chromatography (liquid chromatography of ions). It applies to a variety of water types (drinking water, raw water, surface water, partially treated water, swimming-pool water) and covers sample pretreatment, chromatographic separation, detection, calibration and quality control for bromate concentrations in the range 0.5 µg/L to 1 000 µg/L (with appropriate preconcentration or dilution).

Key topics and technical requirements

• Analytical principle: anion exchange separation using an ion chromatograph with a conductivity detector (CD) combined with a chemical suppressor; UV detection (190–205 nm) may be used only to confirm CD results.
• Working range: 0.5 µg/L to 1 000 µg/L bromate; low-level determinations may require an on-line or off-line concentrator (preconcentration) column.
• Resolution requirement: peak resolution R between bromate and the nearest peak (typically chloride) must not be less than 1.3.
• Recovery and quality: preconcentration recovery should be within 80%–120%. Calibration must follow ISO 8466-1 or ISO 8466-2 and quality controls (replicates, standard additions if matrix effects suspected) are required.
• Interferences & pretreatment:
  • Ions such as nitrate, chloride, carbonate, bicarbonate and sulfate can reduce concentrator capacity and interfere with quantification; these may need removal or dilution.
  • Metal ions (e.g., Ba, Ag) from pretreatment can bind resins; use metal clean-up columns or special exchangers.
  • Solid particles, mineral oils, detergents and humic substances shorten column life-filtration/cleanup recommended.
  • Some organic acids were tested and found not significant at tested concentrations (see Annex E).
• Eluents: two types are described - Type 1 (lower concentration) for separation and Type 2 (higher concentration) for flushing strongly retained ions; eluents must be degassed and stored in the dark, renewed regularly.
• Typical apparatus: eluent reservoirs & degasser, gradient-capable pump, autosampler/injection loop, column-switching valves (for on-line preconcentration), concentrator and separator columns, suppressor-equipped conductivity detector, optional UV detector, data acquisition system.

Applications

• Routine monitoring of drinking water compliance and treatment plant performance.
• Environmental monitoring of surface and raw waters.
• Quality control in water treatment, disinfection and pool water management (bromate forms as a disinfection by‑product).
• Validation and method development for laboratories implementing ion chromatographic bromate assays.

Who should use this standard

• Environmental and municipal water laboratories
• Public health and regulatory bodies enforcing potable water limits
• Water treatment operators and consultants
• Instrument and column manufacturers providing validated methods and systems

Related standards

Normative references included in ISO 15061:

• ISO 3696 (Water for analytical laboratory use)
• ISO 5667‑1 / ‑2 / ‑3 (Sampling guidance)
• ISO 8466‑1 / ‑2 (Calibration and evaluation of analytical methods)

Keywords: ISO 15061, bromate determination, ion chromatography, water quality, dissolved bromate, conductivity detector, preconcentration, liquid chromatography of ions.