Mass-Labelled PCDD Internal Standard Solution

which contains the following;

MASS-LABELLED PCDDs(ng/ml)
MASS-LABELLED PCDDs(ng/ml)
1,3,7,8-Tetrachloro[13C12]dibenzo-p-dioxin100
1,2,4,7,8-Pentachloro[13C12]dibenzo-p-dioxin100
1,2,3,4,6,8-Hexachloro[13C12]dibenzo-p-dioxin100
1,2,3,4,6,7,9-Heptachloro[13C12]dibenzo-p-dioxin100