A comparison of colloid-contaminant C18-based isolation techniques using PCB contaminated humic substances and interstitial water

The bioavailability of sediment contaminants may be reduced by the presence of interstitial colloids; therefore, being able to efficiently isolate colloidal phase contaminants is important to predicting adverse biological effects. Reverse phase chromatography performed on laboratory-packed C18 columns has shown promise for isolating colloid-associated contaminants from marine sediment interstitial waters. This study investigated the effects of the stationary phase particle-size on the distribution of colloidal and freely-dissolved contaminants using C18 material coated on particles 0.075 and 3.0 mm in diameter. Comparisons were performed with PCB-spiked humic and fulvic acid solutions and environmentally contaminated sediment interstitial waters. Similar partition coefficients were generated for approximately 50 PCB congeners using the 0.075 and 3.0 mm particles with humic acid solution and interstitial water but not the fulvic acid solution which differed greatly. However, the method using 3.0 mm C18 particles demonstrated a hysical break-down or ‘shattering’ of the particles which interfered with the chromatography. This evaluation showed that use of 0.075 mm particles for performing laboratory packed column chromatography to separate freely-dissolved and colloidal phases is the superior method.