Standard Method # 4500-Norg. Nitrogen is a very important element in water analysis. Very different treatment methods may be required based on not only the concentration of nitrogen present, but also on the predominate species (or type) or nitrogen. Although the NO3-, NO2 and NH3 forms of nitrogen can be determined directly, the organic form must be digested or converted to a 'common' form before analysis can be undertaken. The Kjeldahl digestion converts all forms of nitrogen to ammonia nitrogen, which is then titrated against a known acid standard. SCP SCIENCE provides a number of products to assist in your Total Kjeldahl Analyses. In addition to AccuSPEC Reagents, use the DigiPREP HT digestion system to prepare your samples for titration.