Figure 7

Chromatogram of Sample 3 (archeological birch bark, lower part, ice patch) after hydrolysis. I.S.1: internal standard hexadecane, I.S.2: internal standard tridecanoic acid and *instrument contamination.
Chromatogram of Sample 3 (archeological birch bark, lower part, ice patch) after hydrolysis. I.S.1: internal standard hexadecane, I.S.2: internal standard tridecanoic acid and *instrument contamination.