Kinetex 2.6μ c18 100a column

Test compounds were analyzed by reverse phase HPLC with a Kinetex 2.6μ C18 100A column (3.0 mm x 50 mm, Phenomenex (Torrance Ca)) using Shimadzu (Columbia, MD) LC-20AD system. The mobile phase consisted of solvent A (Water with 0.1% Formic) and solvent B (acetonitrile with 0.1% Formic). The MS detection was performed by using an API 4000 Q trap system. The amount of parent compound was determined on the basis of the peak area ratio (compound area to internal standard area).

Directly after thawing, 95–260 ml of melted sea ice was filtered on 25 mm GF/F filters. The filters were immediately flash-frozen in liquid nitrogen and stored at −80°C until extraction. Filters were extracted in 2 ml acetone/methanol (80:20) and sonicated using a Vibra-cell sonicating probe, operating at 80% in 5-s pulses. High performance liquid chromatographic (HPLC) analyses of the extracts were performed [45 ], using an absorbance diode array-based detector (Spectraphysics UV6000LP). A 150 × 3.0 mm Phenomenex Kinetex 2.6-μ C18 100A column was used for separation. Pigments were identified by their retention time and absorbance spectra (400–700 nm) and compared to pigment calibration standards, provided by DHI Water and Environment, Denmark. Concentrations of the main photosynthetic pigments, chl a and fucoxanthin, were either integrated over area or corrected to brine volume according to Frankenstein and Garner [40 ].