Actually no Im not
There are two approved methods for measuring IBUs and the first one is being phased out.
Solvent extraction followed by UV-Vis absorption, the newer and preferred method HPLC.
The reason UV-Vis is being superseded is that its not all that accurate (give you an example in a minute) Absorption often reports a bunch of other hop products as well as Iso-Alpha.
Without being too much of a nag about it I will repeat that there is an agreed international standard method for measuring IBUs in beer, its described in the Anilitica, note that it doesnt give a frig how much hops you added or when, it reports the amount of Iso-Alpha dissolved in the finished beer, when measured accurately (i.e. HPLC) there is very much a well know and upper limit to the amount that can be dissolved, to describe that as threshold is misleading a threshold is about our ability to sense the human pain threshold is (well the upper one) would be reached by putting both hands flat on a very hot BBQ plate, you pass out from the pain. If we were talking about the ability to taste salt, two things come into play our ability to discriminate and the solubility limit of salt, salt (NaCl) has a known solubility limit of 359g/l at 20oC if I put 500g in a litre of water, 11g will sit on the bottom add more and it to will just sit on the bottom, heat the water and more goes into solution, cool it down and it falls back out.
Whether we can taste the difference between 100g/l and 200g/l would describe the human taste threshold it could be that past 20, 50 or 150 g/l (for example) it just tastes salty and amounts above that are irrelevant to human perception.
If I put 500g of salt in litre of water, then took of the liquid above the salt and bottled it claiming it was in fact a 500g/L salt solution I would be telling a clear untruth (Full of ****, Lying, dumb as dog ****... take your pick).
You can get a lot of hop products into beer but you cant get much over 90IBU (there is measurement error), claiming otherwise is misleading and untrue
This is a snap of the mg/L and IBU measurements of the same 6 samples first by HPLC second by UV-Vis Absorption; I think it clearly shows why one is the preferred method. The results are for samples taken during an ongoing experiment on Cube Bitterness a friend and I are trying to pin down exactly what happens in a no-chill cube, the table shows the rise in bitterness over time in a cube.
Mark
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