I did find thisFrom my limited knowledge 20Kda hgh is not 191aa rather 176aa.
Can hplc not differentiate between the two?
Maybe @janoshik can give his input on this and on what @sheldonator commented on the YT video in the quote above.
My smooth brain reads it as a method of quantifying GH1 (22 kDa) and differentiating it from other isoforms present in serum/plasma (Anyone smarter, please correct me if I'm wrong).
Not sure if that transfers over to a testing method for what we would be interested in.
Would love to hear more about it from the author of that comment on youtube though!