"In future, the system will also be used to carry out analyses in the growth market of the pharmaceutical industry," says Nils Müller, head of research and development at C. Gerhardt. 

The Dumas method offers clear advantages over the wet-chemical Kjeldahl method: it is faster, requires less preparation and is safer for laboratory technicians as they do not come into contact with hazardous chemicals.

From the solid sample to the finished result, the system works through five steps. In the first step, the samples are thrown into the furnace by the autosampler. In the furnace, the samples are being combusted completely at around 1,000°C with the help of an oxidation catalyst. The combustion of the samples produces a gas mixture with all possible components – but only the nitrogen content is of interest in order to calculate the protein content.

Step 2 takes place in the copper reactor. There, the nitrogen oxides are reduced to nitrogen pairs and excess oxygen from the combustion is captured. The third step is the removal of water from the gas flow using a two-stage water separation system. After water separation, only the carrier gas, nitrogen and carbon dioxide remain in the gas stream.

"This is where the valve block with the VYKA media-separated solenoid valves from Festo comes into play and helps us to remove the carbon dioxide via our adsorber system," Müller says. 

Festo's solution distributes sample and purge gas in the CO2 traps. 

"The valve block meets the strict requirements for tightness and critical operational reliability within the 24-valve configuration of our system," Müller says.

The high tightness and low energy consumption of the valve system increases the efficiency of the system and reduces the cooling times of the adsorbers, as the device manages with low operating temperatures overall. The valve block with the VYKA valves therefore contributes to overall productivity. 

"We were particularly impressed by the commitment and support shown by the Festo experts in their Project Office for the life science market in developing our customer-specific solution," Müller says. 

Removing CO2 is simple on a small scale, but becomes complex when hundreds of samples are processed every week. 

"We teamed up with Festo to develop a customized, reliable gas distribution system on the carbon adsorber that makes it much easier to use and automatically clean our adsorbers," Müller says. 

After the adsorbers, N-Realyzer has separated all elements of the combustion gas except nitrogen. This means that the nitrogen content can be quantified using a thermal conductivity detector (TCD).

The patented autosampler and the adsorber system with the valve block from Festo, in combination with the software, offers laboratory users flexibility. The working times of the device can be set in the software so that, after appropriate preparation the day before, the device can start work before personnel are present in the laboratory. In addition, hardly any chemicals are used. 

Whether solid or liquid, with a high or low nitrogen content: N-Realyzer delivers reliable and precise results for up to 100 samples in series for any sample matrix. The patented autosampler prevents samples from being mixed up. Thanks to the high variability in the sample sequence, users can flexibly "insert" urgent samples. Thanks to the two-stage water separation, the water content of aqueous samples is completely removed. The benefit: laboratories can analyze aqueous samples in series without risking the failure of their device.

During development, the development team placed emphasis on improving user and maintenance friendliness. For example, unlike its predecessor model, N-Realyzer is cubic and no longer rectangular. It is also mounted on a turntable. This means that all parts are easily accessible. The quick replacement of all process-relevant components during operation saves working time and ensures smooth operation. 

"The use of high-quality materials and the carefully considered system design not only ensures precise analysis, but also simple maintenance and servicing,” Müller says. “The tool-free sealing concept enables all consumables to be replaced quickly.”