How are Beverages Tested for Caffeine?
There are a number of different methods used to test for how much caffeine is in a particular beverage. The tests used depend on a number of factors, including how precise the measurements need to be. In a lab setting the three most common tests are liquid chromatography, gas chromatography, and UV spectroscopy. Both liquid and gas chromatography operate on much the same principle, passing a mobile phase of something through a stationary bed to separate parts out. Basically, whatever you are trying to test is passed into a column of some sort of material. The various parts, such as the caffeine in a drink, separate out because of the different affinities they have for whatever is used as the stationary bed. The output of this process, a chromatogram, is a graph with different peaks, with each peak representing a different component. So once a test like this is run on a drink, whoever is doing the test just needs to look at the chromatogram for the caffeine peak, to determine how much c
