It's clear that caffeine is detected through a colorimetric reaction (the murexide reaction), consequently old-school hackers will use a Spec 20: https://en.wik

It's clear that caffeine is detected through a colorimetric reaction (the murexide reaction), consequently old-school hackers will use a Spec 20: https://en.wikipedia.org/wiki/Spectronic_20 https://en.wikipedia.org/wiki/Spectronic_20 2700 dollars for a single-wavelength colorimeter? That's madness!