We then extracted the solid sample residues in 200 mL of sodium acetate buffer (pH 4.0) for 6 h. We filtered the supernatants with 0.4 μm polycarbonate filters and set aside 20 mL of filtrate from each sample split for MRP and total P analyses. We added 200 mL of ultrapure water to the solid residue for each sample split as a wash step after the above reductive step, shook samples for 2 h, and then centrifuged them at 3,700 rpm for 15 min. We took 20 mL aliquots from the filtrate for each sample split for MRP and total P analyses, and kept them refrigerated until analysis within 24 h. We filtered the supernatants with a 0.4 μm polycarbonate filter. We shook samples for 8 h and then centrifuged them at 3,700 rpm for 15 min. This step produces effervescence, so the solution should be added slowly to the sample. 147.12 g/mol 7.4 g) was added to each sample split, followed by 200 mL of citrate-bicarbonate solution (pH 7.6). For a given sample, we weighed four sample replicates (2 g) and placed each in 250 mL HDPE bottles. Prior to the extraction, we freeze-dried, ground and sieved sediment samples to less than 125 μm (Ruttenberg 1992). These procedures apply to all NMR spectra files.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |