Comparison of XAD resins for the isolation of humic substances from seawater

The XAD-2010 and XAD-16 polystyrene based resins have for the first time been used for the isolation of humic substances (HS) from seawater in this study. The adsorption efficiencies and recoveries of HS were compared using batch and column isolation procedures with different XAD resins (XAD-2, -4, -16, -2010 and XAD-4+XAD-2, XAD-2010+ XAD-16, XAD-16+XAD-2010). The recoveries of adsorbed HS were evaluated by the comparison of the size-exclusion chromatogram (SEC) peak areas of the seawater sample and of the NaOH effluents from different XAD columns. The batch recoveries of adsorbed HS varied between 35.2+/-2.4% (XAD-4) and 72.5+/-5.2% (XAD-2010). The XAD-16 resin had the best adsorption properties (column procedure, recovery 89.5+/-0.5%) and XAD-2010 the best elution properties for seawater HS. The batch isolation procedure for seawater HS has been worked out. (C) 1999 Elsevier Science B.V. All rights reserved.