Due to the direct heat transfer of the contact of block to sample tube, lower set temperatures are required to achieve the boiling temperature.
Differences between IR and block digesters.
The standard suction module is mainly used for unproblematic and dry samples.
The suction module with condensate trap is used for aqueous samples, to speed up the digestion process as it avoids backflow of the evaporated water into the sample. Hence the evaporation of water is faster and the boiling point is reached earlier, it also helps avoid cross-contamination of problematic samples.
No, only one temperature setting can be applied at the same time.
All types of BUCHI Kjeldahl sample tubes (100 mL, 300 mL, 500 mL) as well as 3rd party tubes with a capacity of 250 mL and flat bottom tubes for reflux digestion (e.g. COD and aqua regia digestion) can be used in the same instrument.
IR digesters are up to 30 minutes faster than block digesters .
By using the SpeedDigester with the dedicated H2O2 suction module the sample is digested in absence of any catalyst but by continuously adding H2O2during operation. This further accelerates the process by 70 min (yellow vs. green graph) but involves the operator’s attendance.
A very fast (30 minutes) and environmental sound digestion (as no heavy metal catalyst is used) is achieved by continuously adding H2O2via capillary funnels (yellow graph).
To add H2O2continuously during digestion a specific suction module with funnels is required
Weights of samples which are homogenous and high in nitrogen content can be reduced so that micro-Kjeldahl parameters can be applied (e.g. fertilizer , cosmetics).
Generally, optimal conditions can be estimated with the help of BUCHI’s Kjeldahl Calculator app. KjelCalc predicts the use of chemicals for digestion and distillation and determines the right parameters.