The extracted lipids were esterified/transesterified to fatty acid methyl esters as reported previously (Foseid et al. 2017) . In short, the NL and PL fractions were redissolved in 2 mL nheptane (HiPerSolv CHROMANORM quality, VWR), while the FFA fractions were redissolved in 1 mL boron trifluoridemethanol solution (14%, Merck KGaA, Germany). Sodium methoxide, 3.3 mg mL -1 , was made by dissolving metallic sodium (Merck) in methanol (HiPerSolv CHROMANORM quality, VWR). 1.5 mL of the sodium methoxide solution was added to the NL and PL fractions and the samples were shaken horizontally for 30 min at 350 rpm (Biosan Ltd., PSU-10i, Latvia), then left to settle for 10 min. The heptane phases were transferred to vials and stored at -24 °C. The FFA fractions were heated in a water bath for 5 min at 70 °C, 1 mL n-heptane was then added and the samples mixed with a vortex mixer. The heptane phases were transferred to vials and stored at -24 °C prior to GC-MS analysis.
Foseid L., Natvik I., Devle H., & Ekeberg D. (2020). Identification of fatty acids in fractionated lipid extracts from Palmaria palmata, Alaria esculenta and Saccharina latissima by off-line SPE GC-MS. Journal of Applied Phycology, 32(6), 4251-4262.
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