Sulfonated-PCBs and OH-sulfonated-PCBs: An insight into their environmental formation and identification

Sulfonated-PCBs (-SO₃H) or S-PCBs, and OH-sulfonated-PCBs (−OH, −SO₃H) or OH-S-PCBs are recently discovered PCB metabolites, deriving from PCB degradation. For these chemicals their precise chemical identity, measured physico-chemical properties, as well as their potential ecotoxicological and toxicological effects, are still unknown. Here, the formation of these new environmental contaminants was first explored by performing single congener (PCB 31 and PCB 155) degradation experiments using two different microbial inocula. In an additional experiment, S-PCB 155 was used as parent compound to verify the production of OH-S-PCBs. The overall aim was to further investigate the array of sulfonated metabolite congeners which can originate from a known single parent compound and furnish some additional evidence on their identity. The results obtained reveal that di- and tri- metabolite congeners were formed from a tri-PCB, and penta-, and hexa- metabolite congeners from a hexaPCB. In general, however, the sulfonated-PCB class is the least produced in terms of the number of congeners, compared to both OH-sulfonated-PCBs and OH-PCBs. An additional experiment revealed the probable production of OH-S-PCBs, obtained starting with S-PCB 155 as parent compound.