L490

Hi I have opened a new bottle of nonafluoro-1-butanesulfonic Acid CAS 375-73-5. As per the storage instructions of the MSDS I blanketed the unused material in an inert gas (argon) before stoppering the container for storage. The unused material has gone from a colourless liquid to a pale brown colour after the gas blanket application. Can anyone suggest what is happening here please - I have two thoughts - the gas steam was not dry or the gas steam is contaminated with something other than argon (maybe oil from the regulator ?) Any ideas or experience would be gratefully received. Thank you