Devarda's Alloy Method for Total Nitrogen Determination

A modified semimicro‐Kjeldahl procedure for total nitrogen (N) determination to include No 3 ‐ ‐N, NO 2 ‐ ‐N, or both is described. The method involves use of Devarda's alloy as a reducing agent in the pretreatment procedure to convert NO 3 ‐ ‐N, or NO 2 ‐ ‐N, into NH 4 + ‐N in 6 N H 2 SO 4 with subsequent Kjeldahl digestion of the sample using a mixture of K 2 SO 4 − Se and concentrated H 2 SO 4 . The proposed method was effective in recovering NO 3 ‐ ‐N or low‐level NO 2 ‐ ‐N from water, soil, plant, and organic N compounds in total N determinations. The method gives essentially the same or slightly higher values for total N in a variety of soils when compared with other commonly used methods. The advantage of the proposed method is that it includes both NO 3 ‐ ‐N and low‐level NO 2 ‐ ‐N in one single pretreatment procedure and gives a smooth digestion during the subsequent Kjeldahl analysis.