Lassaigne's Test
Historical document, translated for reference. It reflects medical knowledge of the 1920s–30s and is not medical advice.
Summary
Lassaigne's test is a chemical procedure used to detect nitrogen in organic compounds. The test involves fusing the dry substance with metallic sodium or potassium, dissolving the residue in water, and treating the filtrate with iron salts and acid to form Prussian blue.
Encyclopedia entry (1928–1936)
LASSAIGNE'S TEST (Lassaigne) for nitrogen in organic compounds. The dry test substance and a small piece of metallic sodium or potassium are placed in a dry test tube, heated until the reaction ceases, and the tube is immediately dropped into a vessel with a small amount of water (caution! violent reaction of sodium or potassium with water!); the tube shatters, and the contents dissolve. After filtering, a few drops of a mixture of FeSO4 and FeCl3 are added to the filtrate, which is then acidified with dilute HCl. If nitrogen is present in the substance, a blue-green coloration forms, and upon standing, a precipitate of Prussian blue appears.
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Cite this page
“Lassaigne's Test.” Soviet Medical Encyclopedia. English translation of Bolshaya Meditsinskaya Entsiklopediya, 1st ed. (Moscow, 1928–1936), ed. N. A. Semashko. https://sovietmedicalencyclopedia.pages.dev/article/lassignes-test/