HBIs and sterols in zooplankton Nansen Legacy Q4

Study Extent

Sampling

Method steps

1. HBIs and sterols were analysed at the University of Plymouth, UK. All samples were freeze-dried (-45 °C, 0.1 mbar, 24-48 h). Total lipids were extracted with chloroform/methanol (2:1, v/v) and cleaned with potassium chloride (0.88 %). Thereafter, samples were saponified with 20 % potassium hydroxide in water/methanol (1:9, v/v) at 70 °C for 1 h. Non-saponifiable lipids were extracted with hexane and purified by open column chromatography filled with SiO2. HBIs were eluted using hexane. The partially purified non-polar lipids containing HBIs were analysed by gas chromatography-mass spectrometry (GC-MS). Quantification of HBIs was achieved by integrating individual ion responses in single-ion monitoring mode, and normalising these to the corresponding peak area of the internal standard and an instrumental response factor obtained from purified standards (Belt et al., 2012). Sterols were eluted from the same silica column using hexane:methylacetate (4:1,v/v). Sterol fractions were derivatised using N,O-bis(trimethylsilyl)trifluoroacetamide (70 °C, 1 h) and analysed GC-MS. Individual sterols were identified by comparison of the mass spectra of their trimethylsilyl-ethers with published data (Belt et al., 2018). Belt, S.T., Brown, T.A., Sanz, P.C., and Rodriguez, A.N. (2012). Structural confirmation of the sea ice biomarker IP25 found in Arctic marine sediments. Environ. Chem. Lett. 10(2), 189-192 Belt, S.T., Brown, T.A., Smik, L., Assmy, P., and Mundy, C.J. (2018). Sterol identification in floating Arctic sea ice algal aggregates and the Antarctic sea ice diatom Berkeleya adeliensis. Org. Geochem. 118, 1-3

1. Calanus glacialis
2. Calanus hyperboreus
3. Calanus finmarchicus
4. Themisto abyssorum
5. Themisto libellula