Tech grade HBr in GAA turned dark

[endo1]

Any reason why a Tech grade 33% HBr in GAA from a professional well known supplier would be ummm... black? Can it be stored OK for a few months at room temp? It might have gotten a little warm in storage over the summer.... Is it still useable?

[Rhodium]

I assume that bromine has formed by some kind of oxidation or by UV-irradiation (sunlight). Add some hypophosphorous acid to the solution and stir for a day, and hopefully the color will be gone. Then store the decolorized acid dark and cool.