The Kjeldahl Method: 140 Years

Description

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). Preface Acknowledgements Contents About the Author 1 Introduction References 2 A Brief History of Organic Elemental Analysis 2.1 Carbon and Hydrogen Analysis 2.2 Nitrogen Analysis References 3 Nitrogen Compounds 3.1 The Kjeldahl Method Applied to Different Nitrogen Compounds References 4 The Kjeldahl Method 4.1 Digestion 4.1.1 Acid Requirements and Temperature 4.1.2 Catalysts and Salt Addition 4.1.3 Hydrogen Peroxide 4.1.4 Sealed Tube Digestion 4.1.5 Microwave Digestion 4.2 Ammonia Distillation and Determination 4.2.1 Titration 4.2.2 Spectrophotometry 4.2.3 Chromatography 4.2.4 Ammonium Ion-Selective Electrode References 5 The Advancement of Kjeldahl Equipment 5.1 Early Devices 5.2 The Caustic Splash Problem 5.3 The Ammonia Distillation Equipment 5.4 Solving the Problem of Fumes Disposal 5.5 The Small Details: Racks and Stands 5.6 The Miniature Equipment: Micro-Kjeldahl Devices 5.7 Kjeldahl Equipment Today References 6 Experimental: Evaluation of Titanium Dioxide as a Catalyst in the Determination of Nitrogen by the Kjeldahl Method 6.1 Introduction 6.2 Acid-to-Salt Ratio 6.3 Catalyst 6.4 Experimental 6.5 Production of a Catalytic Mixture References 7 Important Topics Related to the Kjeldahl Method 7.1 The Carlsberg Foundation and the Carlsberg Research Laboratory 7.2 Nitrogen-to-Protein Conversion Factors 7.3 Reference Materials and Primary Standards 7.4 Food Standards and the Kjeldahl Method 7.5 Patents on Kjeldahl Equipment 7.6 Reviews of the Kjeldahl Method 7.7 A Comparison of the Kjeldahl and Dumas Methods 7.8 Other Methods for Nitrogen Determination Developed in the 1900s References