Industry: Environmental
Instrument: Apollo 9000

Benefits of Nitrogen Monitoring by High Temperature Combustion (HTC)
Nitrogen monitoring can be a critical function for the process control of wastewater treatment and other industrial applications, as well as for seawater analysis. New advances in high temperature combustion (HTC) technology with chemiluminescence detection (CLD) provide a quick and easy way to monitor nitrogen loading by total nitrogen (TN) analysis. Since this analysis can be performed simultaneously with traditional total organic carbon (TOC) analysis, the analytical benefits can be achieved with minimal labor and capital expenditure, boosting productivity and lowering costs over existing nitrogen analysis techniques. This application note will demonstrate the full capability of HTC total nitrogen for a variety of key applications.

Currently, Total Kjeldahl Nitrogen (TKN) is the standard method in many countries for organic nitrogen analysis. The objective of the TKN test is to convert nitrogen, from biological origins or organic forms, into ammonia through a digestion procedure. The ammonia is then determined through a titration procedure. Hence, TKN is the sum of organic nitrogen and ammonia.

TKN = Organic Nitrogen + NH3

While effective, TKN has several drawbacks. Only organically bound nitrogen, in the tri-negative state, is determined by most TKN methods. Therefore, nitrogen in the form of azide, azine, azo, hydrazone, nitrate, nitrite, nitrile, nitro, nitroso, oxime, and semi-carbazone compounds are often not fully digested or detected. Problems during digestion can be caused by a high amount of salt or acid in the sample, causing the digestion temperature to rise above the desired temperature resulting in a loss of nitrogen. Conversely, if the quantity of acid is too low the digestion temperature will be under the desired level, resulting in incomplete digestion. Another concern with the TKN method is the extensive use of sulfuric acid as part of the sample digestion process. In most cases, the steps required to safely run this test, and the environmental precautions that have to be addressed, are actually more stringent than the care required in handling the samples. This is especially true when samples containing pesticides are being analyzed. In summary, Kjeldahl nitrogen is a time-consuming, environmentally unfriendly, and labor-intensive test for laboratory personnel to perform.

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