Iohexol, 100 µg/ml in Acetonitrile, 5ml

2,3,4,4',5-Pentachloro[13C12]biphenyl, 1.2ml x 50ug/ml, nonane

PCB 28, 10.0 µg/ml, Isooctane, 10ml

Perfluoro-n-[1,2-13C2]decanoic acid, 1.2ml x 50ug/ml, methanol