Overview
ISO 10566:1994 specifies a spectrometric method using pyrocathechol violet for the determination of aluminium in water. The standard applies to potable waters, ground waters, and lightly polluted surface and sea waters, and covers both filterable (dissolved) aluminium and acid‑soluble aluminium. The method uses colour formation of the aluminium–pyrocathechol violet complex and measurement at 580 nm to quantify aluminium concentrations.
Key topics and requirements
- Scope: Analysis of dissolved and acid‑soluble aluminium in drinking water, groundwater and lightly polluted surface/sea waters.
- Sample preparation: Filter samples through a 0.45 µm membrane for dissolved aluminium; acidify with nitric acid (HNO3) to pH 1.2–1.5 for acid‑soluble fraction and allow 1 hour for dissolution before filtration.
- Reagents & buffers: Uses pyrocathechol violet reagent, hexamethylenetetramine buffer, magnesium sulfate (to suppress fluoride interference), sodium bicarbonate and specific standard aluminium solutions for calibration.
- Measurement conditions: Form the coloured complex at pH 5.9 ± 0.1, react for specified times (min. 15 min; measure at 60 min), and measure absorbance at 580 nm using cuvettes with optical path lengths of 10 mm or 50 mm.
- Ranges & sensitivity:
- Low range up to 100 µg/l Al with 50 mm cells.
- High range up to 500 µg/l Al with 10 mm cells.
- Limit of detection: 2 µg/l when using 50 mm cells and a 25 ml test portion.
- Example sensitivity: 100 µg/l yields ~0.25 absorbance units with 25 ml and 10 mm cells.
- Interferences & controls:
- Fluoride forms stable complexes with Al - suppressed by added magnesium.
- Iron can produce coloured complexes; iron is reduced and complexed with 1,10‑phenanthroline to minimize interference.
- Organic colouring (humic substances) may interfere; oxidative digestion (H2O2–HNO3) may be needed.
- Contamination control: Use plasticware (avoid glass) cleaned and acid‑rinsed to prevent aluminium contamination; analytical reagent quality and lot testing for pyrocathechol violet are recommended.
- Precision: Volumes and masses specified are typically ±1% unless otherwise noted.
Applications and users
ISO 10566:1994 is used by:
- Environmental and public‑health laboratories monitoring water quality.
- Municipal water utilities and treatment plants for compliance and process control.
- Regulatory agencies and consultants conducting field and laboratory aluminium analysis.
- Research labs studying aluminium mobility and water chemistry.
Keywords: ISO 10566:1994, aluminium determination, pyrocathechol violet, spectrometric method, water quality, detection limit, potable water, groundwater, surface water.
Related standards
- ISO 5667‑3:1994 - referenced for sampling, preservation and handling of water samples used with this method.