| Summary: | Maintenance and Update Frequency: notPlanned Statement: Water samples were taken on-board the vessel and stored under cool and dark conditions until filtering took place on land. Samples were analysed and QC procedures were carried out in the Ocean Colour Laboratory. Pigment analysis 4 litres of sample water was filtered through a 47 mm glass fibre filter (Whatman GF/F) and then stored in liquid nitrogen until analysis. To extract the pigments, the filters were cut into small pieces and covered with 100% acetone (3 mls) in a 10 ml centrifuge tube. The samples were vortexed for about 30 seconds and then sonicated for 15 minutes in the dark. The samples were then kept in the dark at 4 °C for approximately 15 hours. After this time 200 µL water was added to the acetone such that the extract mixture was 90:10 acetone:water (vol:vol) and sonicated once more for 15 minutes. The extracts were centrifuged to remove the filter paper and then filtered through a 0.2 µm membrane filter (Whatman, anatope) prior to analysis by HPLC using a Waters Alliance high performance liquid chromatography system, comprising a 2695XE separations module with column heater and refrigerated autosampler and a 2996 photo-diode array detector. Immediately prior to injection the sample extract was mixed with a buffer solution (90:10 28 mM tetrabutyl ammonium acetate, pH 6.5 : methanol) within the sample loop. Pigments were separated using a Zorbax Eclipse XDB-C8 stainless steel 150 mm x 4.6 mm ID column with 3.5 µm particle size (Agilent Technologies) with gradient elution as described in Van Heukelem and Thomas (2001). The separated pigments were detected at 436 nm and identified against standard spectra using Waters Empower software. Concentrations of pigments were determined from standards (Sigma, USA or DHI, Denmark). Spectral absorption 4 litres of sample water was filtered through a 25 mm glass fibre filter (Whatman GF/F) and the filter then stored flat in liquid nitrogen until analysis. Credit Lesley Clementson This record contains ...
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