850 TOTAL KJELDAHL NITROGEN - TKN
TKN
Total Kjeldahl Nitrogen in H2O. Total reduced nitrogen by the wet oxidation of H2O using micro Kjeldahl procedure with sulfuric acid and digestion catalyst.
Summary: The Total Kjeldahl Nitrogen (TKN) method is based on the wet oxidation of nitrogen using sulfuric acid and digestion catalyst. The procedure converts organic nitrogen to the ammonium form. Ammonium is subsequently quantitated by the diffusion-conductivity technique. The procedure does not quantitatively digest nitrogen from heterocyclic forms (bound in a carbon ring) or from oxidized forms such as nitrate and nitrite. The method has a detection limit of approximately 0.1mg/L N.
Sample amount required: The analysis requires 10 mL sample, but 50 mL is requested to allow for quality control.
Samples should be kept under refrigeration until analysis can be completed.
Carlson, R. M. 1986. Continuous flow reduction of nitrate to ammonia with granular zinc. Anal. Chem. 58:1590-1591.