CAS 56558-18-0 appears in our catalog under these names: PCB No. 121, PCB No. 121 10 µg/mL in Isooctane, 2,3',4,5',6-Pentachlorobiphenyl, PCB 121, ROTI®Star, 5 mg, glass, PCB 121, Concentration: 100 µg/ml Solvent: Isooctane. Offered by: Dr. Ehrenstorfer, Biosynth, Roth, HPC Standards. Available pack sizes: 5mg, 10ml, 25mg, 10mg, 50mg, 1x5ml.