Abstract
A continuous measurement system for free cyanide has been developed based on the principle of diffusion across a gas-permeable membrane to affect the separation of hydrogen cyanide from the acidified sample solution. The cyanide absorbed in the alkaline indicator solution is subsequently analyzed by an indirect technique using a silver ion-selective electrode. In the concentration range of 30 to 400 μg CN/L, the accuracy and precision of this method is approximately two percent. The detection limit of this system is approximately 0.5 μg CN/L.