Quinine is an alkaloid primarily used as an antimalarial medication, effective against Plasmodium falciparum malaria, particularly when other treatments fail. It is also used to treat nocturnal leg cramps due to its muscle relaxant effects, though this application is limited by side effects like cinchonism (tinnitus, headache, nausea). As a flavoring agent, quinine provides the bitter taste in tonic water. In laboratory settings, quinine serves as a fluorescent standard for spectroscopy and calibration due to its strong fluorescence in acidic solutions, making it suitable for analytical chemistry and biochemical assays. This high-purity product (≥98.0%) is intended for fluorescence applications.