Sensing dissolved sediment porewater concentrations of persistent and bioaccumulative pollutants using disposable solid-phase microextraction fibers

Polymer coated glass fibers were applied as disposable samplers to measure dissolved concentrations of persistent and bioaccumulative pollutants (PBPs ) in sediment; porewater. The method is called matrix solid-phase microextr action (matrix-SPME), because it utilizes the entire sediment matrix as a r eservoir for an equilibrium extraction: a glass fiber with a 15 mum coating of poly(dimethylsiloxane) (PDMS) was placed in a sediment sample until the PBPs reached their equilibrium distribution between the PDMS and the sedim ent matrix (1-30 days). PBP concentrations in the PDMS were determined by g as chromatography, and they were divided by PDMS water partition coefficien ts to derive at dissolved porewater concentrations. This approach was appli ed to measure porewater concentrations of spiked as well as field sediment, and several hydrophobic organic substances (log K-ow 5.2-7.5) were measure d with high precision in the pg to ng/L range. Simple equilibrium partition ing is the basis for the substantial concentration factors that are built i nto matrix-SPME and for the low demands in materials and operation time. Ma trix-SPME was in this study directed at the determination;of dissolved pore water concentrations in sediment, and it is further expected to be applicab le to other environmental media, to field sampling, and to the sensing of f ugacity.