Available Cyanide Analysis
Available Cyanide
The FS3700 is a compact, modular system for flow injection analysis of available or total cyanide. The FS3700 measures available cyanide by a ligand- exchange, gas diffusion technique coupled with amperometric detection in accordance with USEPA Method OIA-1677-09 and ASTM D6888-09. This non- distillation technique provides accurate measurement of available cyanide in the presence of thiocyanate, sulfite and thiosulfate interferences. A sulfide removal acidification reagent is added in-line to samples containing this interference. A schematic drawing of the FS3700 highlighting the principal steps of the ligand-exchange, gas diffusion cyanide analysis technique is presented below.
Learn about the products used in this analysis:
Principle of Operation For available cyanide measurement, samples are treated with ligand exchange reagents to liberate the cyanide ion (CN - ) (1). A sample is then injected into a carrier stream and acidified (2). Under acidic conditions CN - converts to hydrogen cyanide (HCN) and diffuses across a hydrophobic membrane into a basic acceptor solution (3), where it converts back to CN - and is carried into the flow cell of an amperometric detector. Cyanide ions react with a silver electrode and generate current proportional to the cyanide ion concentration (4). WinFlow software displays the detector response in real-time as a peak as the sample passes through the flow cell. The resulting peak height is proportional to cyanide concentration present in the sample.
1
3
Pump
Sample
Gas Diffusion Module
Waste
2
Waste
4
Carrier
Valve
Inj. Loop
Detector
Waste
Acid
Membrane
Base
1 Ligand exchange Pretreatment MCN - + LE MLE + CN -
Acidification CN - + H +
2 3 4
HCN (g)
HCN
HCN
HCN
Membrane
CN -
CN -
CN -
Amperometric Detection 2 CN - + Ag
Ag(CN) - + e - at + 0.0 V 2
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