Overview
ISO 14403-1:2012 specifies a validated laboratory procedure for the determination of total cyanide and free cyanide in water using flow injection analysis (FIA). The standard covers a wide range of water matrices (ground, drinking, surface, leachate, waste water and with adaptations, seawater) and cyanide concentrations from 2 µg/L to 500 µg/L (expressed as cyanide ions). A practical working range described in the document is 20–200 µg/L, adjustable by dilution or changing injection volume.
Key topics and technical requirements
- Analytical principle: automated FIA manifold introduces sample and reagents; cyanide is converted to hydrogen cyanide (HCN), separated by gas-diffusion across a hydrophobic membrane, absorbed in NaOH and detected photometrically.
- Total vs free cyanide:
- Total cyanide: complex-bound cyanide is decomposed by UV-B irradiation (with a thermoreactor at ~85 °C) prior to diffusion to liberate cyanide from complexes.
- Free cyanide: UV decomposition is omitted; specific treatments (e.g., tetraethylenepentamine for certain nickel complexes) are described.
- Detection chemistry: absorbed cyanide reacts with chloramine‑T to form cyanogen chloride, which reacts with pyridine‑4‑carboxylic acid and 1,3‑dimethylbarbituric acid to produce a red dye measured by a flow photometer.
- Interferences & sample handling:
- Oxidizing agents (e.g., free chlorine) degrade cyanide - neutralize with sodium thiosulfate where necessary.
- Sulfide, sulfite, nitrite, carbonyl compounds and thiocyanate can interfere; procedures (lead carbonate treatment, sulfamic acid in buffer, ethylenediamine addition) are provided.
- Particulates (>0.1 mm) must be removed to avoid clogging and photometric bias.
- Reagents & calibration: potassium cyanide or potassium tetracyanozincate reference solutions and multi-point calibration (minimum five levels) across the working range; stability and preparation details included.
- Safety: handling and disposal warnings for toxic cyanide compounds.
Applications and users
ISO 14403-1:2012 is intended for:
- Environmental and water quality testing laboratories
- Municipal and industrial wastewater monitoring
- Drinking water utilities and regulators enforcing cyanide limits
- Instrument manufacturers and labs implementing FIA-based cyanide analyzers
The method is optimized for high-throughput, automated analysis of multiple samples with reproducible calibration and documented performance characteristics.
Related standards
Keywords: ISO 14403-1:2012, flow injection analysis, FIA, cyanide determination, water quality, total cyanide, free cyanide, gas diffusion, UV decomposition, environmental monitoring.