Optimization of solid-phase extraction procedure for determination of polychlorinated dibenzo- p-dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls in humic acid containing water.

A solid-phase extraction (SPE) method was optimized for accurate determination of polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (CoPCBs) in humic acid containing surface water. Recovery experiments using humic materials revealed that humic acids permit dioxins to pass through an octadecylsilica (C(18)) extraction disk by associating with them under weakly alkaline conditions. Acidification of the sample before percolation improved this otherwise insufficient recovery.