Then, Rapport developed a multi-step process which, eventually, allowed him to isolate this vasoconstricting substance as pale yellow crystals – just a few milligrams from 900 litres of serum. In 1948, they published their findings, calling these precious crystals ‘serotonin’. A year later, now at Columbia University, Rapport identified the chemical structure of serotonin as 5-hydroxytryptamine, or 5-HT.
