Isolation of marine sediment colloids and associated polychlorinated biphenyls: An evaluation of ultrafiltration and reverse-phase chromatography

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Environmental colloids are suspected of having significant effects on nonpolar organic contaminant geochemistry, transport, and bioavailability. However, environmental data on colloid-contaminant interactions is limited because isolating colloids from the dissolved and particulate phases is problematic. In this study, two practical methods using ultrafiltration and reverse-phase chromatography were evaluated for isolating environmentally contaminated marine sediment interstitial water colloids and associated PCBs. In assessing each method, ultrafiltration demonstrated extensive sorption of radiolabeled nonpolar compounds (>90%) and a re-occurring breakthrough phenomena, both of which compromise the method for accurately assessing colloid-PCB interactions. Conversely, C18 reverse-phase chromatography, performed using laboratory-packed columns, generated reproducible organic carbon-normalized colloidal partitioning coefficients (K(coc)) that agreed with literature and theoretical considerations. Evaluations of sample flow rate and prefiltration size along with potential for C18 bed saturation indicated that these parameters have only a minor (e.g., less than a factor of 2) effect on the calculated contaminant distribution coefficients. Of the two methods evaluated, reverse-phase chromatography was the most promising for quantifying environmental colloid-PCB interactions.

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Environmental Science and Technology