Combination of Catalysts to Reduce Digestion Time in the Determination of Nitrogen

The time required for the determination of nitrogen has been materially reduced since Kjeldahl (1) first proposed his original method. This reduction has been made possible by introducing into the reaction mixture potassium sulphate and catalysts such as mercury and copper. Just recently, the use of selenium has been advocated as a catalyst. Although Lauro (2) was the first to investigate the use of selenium, this substance has been combined with other catalysts by several investigators (3 to 11 inc.) Of these workers, several (7, 8, 10) have found this element to reduce materially the amount of nitroge n obtained in the analysis. Sandstedt (11) also has found with selenium some loss of nitrogen on long heating.