Sodium 1-pentanesulfonate is an organic sulfonate salt with the molecular formula C5H11NaO3S. It is a white to off-white crystalline powder that is highly soluble in water and polar organic solvents such as methanol and acetonitrile. It is a member of the alkylsulfonate family, characterized by a five-carbon (pentyl) chain attached to a sulfonate group. Its primary and most significant application is as an ion-pairing reagent in reversed-phase high-performance liquid chromatography (HPLC). It is used to improve the separation, retention, and peak shape of basic compounds, such as amines and pharmaceutical actives, by interacting with charged analytes. It is also employed in capillary electrophoresis and as a surfactant or phase-transfer catalyst in certain organic synthesis reactions. As a specialized reagent, it is a standard tool in analytical chemistry laboratories for method development and quality control, particularly in pharmaceutical analysis. It is considered a mild reagent but requires standard laboratory safety precautions, including the use of personal protective equipment to avoid inhalation or contact.