Quinine is highly fluorescent

Tonic water, in normal light and ultraviolet “black light”.

Quinine occurs naturally in the bark of the cinchona tree, though it has also been synthesized in the laboratory.
The medicinal properties of the cinchona tree were originally discovered by the Quechua, who are indigenous to Peru and Bolivia

Quinine is highly fluorescent (quantum yield ~0.58)

Because of its relatively constant and well-known fluorescence quantum yield, quinine is used in photochemistry as a common fluorescence standard.
The UV absorption peaks around 350 nm (in UVA).
Fluorescent emission peaks at around 460 nm (bright blue/cyan hue).


Schweppes tonic water contains quinine

[Opioids] Street drugs are frequently “cut” (mixed or combined) with other substances, such as caffeine, powdered milk, quinine, and strychnine, to dilute the concentration of the active ingredient.
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