ISO 20950-1:2018

Water quality — Determination of available weak and dissociable (WAD) cyanide — Part 1: Method using ligand exchange, flow injection analysis (FIA), gas-diffusion and amperometric detection

Scope

This document specifies operationally defined methods for the determination of available WAD cyanide in various types of water such as drinking, ground, and surface, waters, and metallurgical processing tailings reclaim, heap leach barren, mill slurry tailings and leaching solutions, with cyanide concentrations from 5 µg/l to 2 000 mg/l expressed as cyanide ions in the undiluted sample. The range of application can be changed by varying the operation conditions, e.g. by using a different injection volume, thicker membrane, detector response, etc.
NOTE ISO 2080:2008, 3.105, defines free cyanide. The concentration of available WAD cyanide includes free cyanide and some of the metals complexed in solution as determined by a specified analytical method but not all of the metal complexes present in total cyanide (3,191).
In this method, six suitable mass concentration ranges from 5 µg/l to 50 µg/l, from 50 µg/l to 500 µg/l, from 0,5 mg/l to 5 mg/l, from 5 mg/l to 50 mg/l, from 50 mg/l to 500 mg/l and from 500 mg/l to 2 000 mg/l are described.