ALBERT

Description: Phycotoxins (Fuat Dursun, Bernd Krock): An 8 L aliquot of pooled water from surface water, 10 m depth and the thermocline was filtered through 5 μm polycarbonate filters for azaspiracid and karlotoxin determination. The filters were extracted by repeated rinsing with methanol, the methanolic extracts were transferred to centrifugation filters and filtered at a cutt-off of 0.45 μm by centrifugation. Filtrates were transferred into analytical glass vials for posterior LC-MS/MS determination at AWI. Net tows of each station were combined and ajusted to 1 L with filtrated seawater. Aliquots of 200 mL, 50 mL, and 20 mL were taken for DNA analysis, Cell isolation, and fixation, respectively. The remaining aliquot of the net tow concentrate was filtered through a filter array of 200, 50, and 20 μm meshes. The residue of each mesh was rinsed with filtrated seawater into a centrifugation tube, homogenized by shaking, and divided into two aliquots. Both aliquots of each size fraction were centrifuged at maximum speed for 15 min. After centrifugation, supernatants were decanted and the remaining cell pellets resuspended with a small volume of filtrated seawater and transferred to cryovials containing ceramic beads. The samples were centrifuged again and supernatants carefully removed with a pipette. To one of the two size fraction aliquots 500 μL methanol was added and the same volume of dilute acetic acid to the other. All samples were homogenized with FastPrep instrument by reciprocal shaking at maximum speed and homogenated were centrifuged. After centrifugation, the toxin containing extracts were removed and transferred to centrifugation filters. The extracts were filtered by centrifugation and the filtered extracts were transferred into analytical glass vials for LC-MS/MS and LC-FLD determination, respectively, in the home lab.