Comparison of four documents describing adrenaline purification, and the work of three important scientists, Keizo Uenaka, Nagai Nagayoshi and Jokichi Takamine.

•Keizo Uenaka was the scientist who practically isolated adrenaline as crystal.•Adrenalin purification methods released in 1901 was based on Uenaka's hand-written document, “On adrenalin, Memorandum, July to December, 1900”.•Nagayoshi Nagai, Jokichi Takamine and Keizo Uenaka had crucial roles in chemical isolation of ephedrine and adrenaline.