Look at USP 4095982. Fuji are using Sodium benzenesulfonate (Benzenesulfonic acid sodium salt) as an anti-oxidant. As it's use as an anti-oxidant is referenced in a number of other Photographic Patents I think we can be 100% certain that Pavel's got it right. It's used as an anti-oxidant in many other field too and made & sold in bulk quantities.

I have another Polish source calling it "Benzosulifinian sodow" in Orwo RO9. But I suspect this is a Typo or translation in a publication as the sulphonic group translates as Sulfonian as Ron says.

Ian