Gerhardt is offering an acid-resistant version of the Vapodest 20 and the whole Vapodest range of steam distillation units, for total cyanide determination.
When carrying out a total cyanide determination, the pump used for sodium hydroxide solution is modified slightly for dosing acid.
Using hydrochloric acid, the weaker HCN is stripped in the presence of Cu(l) ions at boiling temperature.
The resulting hydrogen cyanide is collected in a diluted sodium hydroxide solution and determined.
This method is based on the official method DIN 38405 D13, and is applicable to water, sewage and sludge, with over 95 per cent recoveries.
The corresponding application documentation is available on request.
The Vapodest 20 was originally developed to run fast and reproducible distillations of Kjeldahl digestion solutions.
The characteristics of this instrument, such as fast heating, good mixing of the sample and the addition of chemicals in a closed leak-tight system, can also be used for distillations of other types of water-steam volatile substances.
