2-Perfluorohexyl-[1,2-13C2]-ethanoic acid (6:2) 2 µg/ml

2-Perfluorooctyl-[1,2-13C2]-ethanoic acid (8:2) 2 µg/ml

2-Perfluorodecyl-[1,2-13C2]-ethanoic acid (10:2) 2 µg/ml