Well I mean yea...with all your exhaustive research on the matter this definitely concludes the thread. buffers never ever go bad. Would you care to include a statement that they're always correct as well? never a bad batch?
Gimme a greak @sneezles61
Hanna instruments has a statement on their website:
"Hanna Tip: Our calibration solutions are designed to have a long shelf life when left unopened. Once opened, a buffer with a pH lower than 7 will last around 3-6 months, while a buffer with a pH over 7 will be good for about 1-3 months."
While I may agree with you that the manufacturer and seller of the solutions might have an agenda of his own in making this statement your contention that they can't "go awry" is nonsense and proven by my experience alone. Unless you're suggesting that my brand new meter is bad or that I don't know how to use it?
What I was hoping for was more anecdotal evidence of how long they may be trusted. How old was your old bottle that tested true?