The remaining 95% FAME from each sample were further separated to obtain purified target compounds on an Agilent 6890N GC equipped with a Restek Rxi-XLB capillary column (30 m, 0.53 mm, 0.5 μm) and a Gerstel preparative fraction collector (PFC). The radiocarbon contents of the isolated n-FAMEs were measured on a mini carbon dating system (MICADAS) equipped with an Element Analyzer via a gas interface system at the Marine Geochemistry Laboratory at AWI, Bremerhaven. Radiocarbon data are reported as fraction modern carbon (F¹⁴C).