title: Passive samplers of hydrophobic organic chemicals reach equilibrium faster in the laboratory than in the field.
abstract: The use of passive sampling methods for monitoring hydrophobic organic chemicals frequently requires the determination of equilibration times and partition coefficients in the laboratory. These experiments are often carried out by exposing passive samplers in a finite water volume, and errors are easily made when the obtained results are applied to the field, where water volumes are essentially infinite. The effect of water volume on the equilibration rate constant is discussed, using a mechanistic model. Application of this model to two literature reports illustrates that aqueous concentrations in the field may be underestimated by a factor of 10 or more, when the water volume effect is neglected. Finally, it is shown that the concept of "sorption capacity" (sampler mass times partition coefficient) allows for a more intuitive understanding of the passive sampling process in small and large water volumes, which may reduce the risk of laboratory-field extrapolation errors.
authors.affiliation: NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB Texel, The Netherlands. Electronic address: kees.booij@nioz.nl.
authors.forename: Kees
authors.initials: K
authors.lastname: Booij
authors.affiliation: Faculty of Environmental Sciences and EULA-Chile Centre, University of Concepcion, P.O. Box 160-C, Concepción, Chile.
authors.forename: Felipe
authors.initials: F
authors.lastname: Tucca
mesh_terms: D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods*; D057927:Hydrophobic and Hydrophilic Interactions; D007753:Laboratories; D008962:Models, Theoretical; D009930:Organic Chemicals / Q000032:analysis* / Q000737:chemistry; D014867:Water / Q000032:analysis / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D014867:Water
keywords: Calibration; Equilibrium; Hydrophobic organic chemicals; Passive sampling; Water