Large volume preconcentration of dissolved hydrocarbons and polychlorinated biphenyls from seawater. Intercomparison between C18 disks and XAD-2 column

The extraction efficiency of XAD-2 and 90 mm C18 Empore disk for trace level determination (ng/L) of organic pollutants (i.e. hydrocarbons, chlorinated compounds) has been evaluated. Whereas C18 Empore extraction disk exhibited higher extraction efficiency for aliphatic hydrocarbons from spiked Milli Q water and seawater, Amberlite XAD-2 column was more efficient for the extraction of individual PCB congeners and most of parent PAHs from spiked Milli Q water. However, in case of seawater analysis, the C18 disk exhibited a higher extraction efficiency for the 3–4 aromatic ring PAHs. Only labile PAHs (i.e. benzo[a]pyrene) and other analytes associated with fine particles were better recovered in XAD-2. Breakthrough volumes for the C18 (φ=90 mm) disks were compound dependent but they were at least 5–10 times lower than typical volumes for XAD-2. However, the C18 disk application enables a solvent usage reduction leading to procedural blank improvement compared to XAD-2 columns.