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).

source:
http://en.wikipedia.org/wiki/Quinine

Schweppes tonic water contains quinine
http://www.schweppesus.com/products/schweppes-tonic-water

[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.
Current Diagnosis & Treatment: Psychiatry, 3e © 2019 by McGraw-Hill Education

related:
https://franzcalvo.wordpress.com/2014/03/30/make-magic-mud-from-a-potato

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Make Magic Mud – From a Potato!

How To Make Magic Mud – From a Potato!
Grant Thompson – “The King of Random”
http://www.youtube.com/watch?v=_0J4dRqg7CE

… potatoes can be chopped up and soaked to leach out the starch, of course the first thing I thought of was making oobleck. My mind was blown when I experimented with this process, and realized the starch would collect at the bottom of the dish, and would stay in place when the water and impurities were poured out.

After only a couple of rinses, it’s amazing to see how pure the starch powder can be. It looks exactly like cornstarch that could be purchased at the store.

I was familiar with the idea of making tonic water glow under UV light, so wondered how it would mix with the starch powder. The result was very gratifying!

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The Science Behind Glow in the Dark Toys and Materials
https://www.wristband.com/content/the-science-behind-glow-in-dark-toys-materials
list of resources!