sarin (zärēnˈ) [key], volatile liquid used as a nerve gas. It boils at 147°C but evaporates quickly at room temperature; its vapor is colorless and odorless. Chemically, sarin is fluoroisopropoxymethylphosphine oxide; it is more toxic than tabun or soman. Sarin acts by interfering with cholinesterase, a chemical that transmits impulses from one nerve cell to the next. A gas mask provides adequate protection against the vapor, but the liquid form can also be absorbed through the skin. Sarin was developed by the Nazis during World War II. In 1995 it was used by Aum Shinrikyo, a Japanese religious sect, in a terrorist attack in the Tokyo subway, killing eight people and injuring thousands.