This book provides a comprehensive survey of the Kjeldahl method and its modifications. It covers all relevant topics, including sample digestion and its variables, distillation and determination of ammonia, equipment development, and concludes with a review of the literature published on the method. Since its introduction in 1883, the Kjeldahl method has been an essential analytical tool for nitrogen determination in research, academic and industrial laboratories. This makes the history of the Kjeldahl method of outstanding relevance to graduate students, postgraduate students, researchers, teachers, and laboratory staff in the fields of analytical chemistry, food/feed analysis, animal/human nutrition, soil/water analysis, and so forth."This method has probably been applied in one modification or another to every possible form of nitrogen, and in perhaps more laboratories than almost any other single type of analytical method" (Kirk, 1950).