Total Nitrogen Bound
The total nitrogen bound (TNb) defines the total pollution of water by nitrogen compounds. It is an analytical parameter for water and is specified in mg/l.
The pollution of nitrogen can appear in form of ammonia, ammonium salts, nitrites, nitrates and organic nitrogen compounds. In contrast to its individual determination, the TNb covers all components in one analytical run. The determination of the TNb value is standardized by the German Institute of Standardisation (DIN EN 12260:2003).
Nitrogen is an essential nutrient for humans and nature. Today the nutrient contents in water are very high. A further increase would lead to eutrophication (overfertilization). Therefore, it is required to monitor this parameter by online measurement systems and thus enabling the regulation of nutrient concentrations in public water.
There are standard methods for determination of nitrogen in water analysis:
On the market, the determination of the TNb competes with the Kjeldahl nitrogen determination (TKN) and with the persulphate digestion according to Koroleff. In contrast to the TKN, the persulphate digestion and the thermal determination of TNb determines inorganic components such as nitrite and nitrate, too. The methods according to Kjeldahl and Koroleff are time-consuming, labor-intensive and require high amounts of chemicals. Hence, these methods are not suitable for fast and accurate online determination of the nitrogen content.
The thermal determination of TNb is characterized by a high degree of automation, increased accuracy as well as by short measuring cycles. Additionally, the user benefits from the fact that hazardous reagents are not necessary at thermal determination.
Commonly two detections of TNb in water samples are used. The detection of the concentration is made with a chemiluminescent- or an electrochemical detector. For chemoluminescence detection ozone is required for the reaction with NO, disadvantaging the approach due to the use of hazardous reagents and the high cost. The electrochemical method is low maintenance, includes lower aquisition costs and the accuracy of its measurement is comparable with the chemoluminescence detection.
LAR Process Analysers AG guarantees the complete oxidation of all organic and inorganic compounds with the ultra-high temperature method at 1,200°C. After the oxidation the TNb is detected by an electrochemical sensor. This is an environmentally friendly method that provides very accurate measurement results. The chemoluminescence detector is available as an option of the QuickTONultra. Operators also have the option to measure the TNb in combination with TOC and COD. The high temperature devices of LAR are applicable in a variety of applications.
|Organic Nitrogen||Ammonia-Nitrogen (NH4-N)||Nitrate-Nitrogen (NO3-N)||Nitrite-Nitrogen (NO2-N)||Particles|
|Kjeldahl Nitrogen TKN EN 25663 (1993)||X||X||(X)|
|Ninorg according to WHG/ AbwaG||X||X||X|
|Ntotal acc. to Koroleff: CTPN decomposition with persulphate||X||X||X||X|
|TNb according to DIN 38409 H27 (EN 12260)||X||X||X||X||X|
|bound Nitrogen acc. to DIN 38409 H28 (Devarda)||(X)||X||X||X|
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