Sodium fusion test

The sodium fusion test is used in elemental analysis for the qualitative determination of elemental halogens, nitrogen and sulfur in a sample. It was developed by J. L. Lassaigne.

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The test involves heating the sample strongly with clean sodium metal, "fusing" it with the sample. The "fused" sample is plunged into water, and the usual qualitative tests are performed on the resultant solution for the respective possible constituents.

Theory

When an organic compound is heated strongly with sodium, any halogens, nitrogen, and sulfur will be converted into inorganic sodium salts such as sodium halide (for halides), sodium cyanide (for nitrogen), sodium sulfide (for sulfur), and sodium thiocyanate (for sulfur and nitrogen).