title: Measuring pyrethroids in sediment pore water using matrix-solid phase microextraction.
abstract: Pyrethroids are hydrophobic insecticides commonly used in both agricultural and urban environments. Their high toxicity to aquatic organisms, including benthic invertebrates, and detection in the sediment at many locations in California, U.S.A., have spawned interest in understanding their bioavailability in bed sediments. A recent study showed good correlation between uptake of 14C-permethrin in Chironomus tentans and solid-phase microextraction (SPME) fibers in sediments. The present study was directed at the development of an SPME technique applicable to trace levels of nonlabeled pyrethroids in sediment. Disposable polydimethylsiloxane fibers were used to detect freely dissolved pore-water concentrations of bifenthrin, fenpropathrin, cis-permethrin, trans-permethrin, cyfluthrin, cypermethrin, and esfenvalerate under agitated and static conditions. Partition equilibrium between fiber and sediment was reached in <5 d when the samples were agitated on a shaker at low speed, while much longer times (>23 d) were needed without agitation. Polydimethylsiloxane to water partition ratios (K(PDMS)) of the seven pyrethroids were measured separately and ranged from 2.83 x 10(5) to 1.89 x 10(6). When applied to field-contaminated sediments, agitated matrix-SPME was able to detect pore-water concentrations as low as 0.1 ng/L. The method developed in the present study may be coupled with bioassays to gain mechanistic understanding of factors affecting pyrethroid toxicities, and applied to field samples to better predict sediment toxicities from pyrethroid contamination.
authors: Department of Environmental Sciences, University of California, 2258 Geology, Riverside, California 92521, USA. whunt001@ucr.edu
authors: Wesley
authors: W
authors: Hunter
authors: Yu
authors: Y
authors: Yang
authors: Fredrik
authors: F
authors: Reichenberg
authors: Philipp
authors: P
authors: Mayer
authors: Jianying
authors: J
authors: Gan
mesh_terms: D001682:Biological Availability; D019015:Geologic Sediments / Q000737:chemistry*; D007700:Kinetics; D011722:Pyrethrins / Q000032:analysis* / Q000493:pharmacokinetics; D012015:Reference Standards; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000493:pharmacokinetics
chemical_list: D011722:Pyrethrins; D014874:Water Pollutants, Chemical