A simple and specific spot-test for lithium based on a fluorescent reaction betwen Li ion and Quinizarin in alkaline medium is described. The resulting compound is extracted in TBP, and fluorescence is observed in the organic phase under illumination with a UV lamp at 360 nm. The sensitivity of the test is 0.1 μg.cm. Applications of the test for lithium include the corresponding cation groups using the H2S and Na2CO3 systematic schemes of analysis; and directly in synthetic mixtures of inorganic ions, mineral water, drugs, dietetic products and blood serum.