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PDMS vials measure PAH activity in polluted soil
Thin PDMS coatings of several thicknesses in glass vials reach equilibrium with soil PAHs so HPLC-fluorescence concentrations can be converted into chemical activities.
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What thermodynamic quantity did the vials aim to measure in soil?
Chemical activity (closely related to fugacity) of hydrophobic organic pollutants.
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified
What polymer format was used as the ESD?
3–12 μm PDMS layers inside 20 mL glass vials.
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified
How were coated vials equilibrated with soil?
18–20 g soil plus 10 mL 0.5 g/L NaN3, rolled 122 h at 6 rpm.
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified
How were PDMS extracts analysed?
HPLC with fluorescence detection (Ex 260 nm; multiple Em wavelengths).
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified
What equilibrium QA/QC comes from several PDMS thicknesses?
Linear CPDMS vs polymer amount with r2>0.90 confirms equilibrium partitioning.
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified
What LoQ range was reported in PDMS concentration units?
0.1 to 2.5 μM, depending on each PAH’s fluorescence yield.
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified
What soil was the test material?
A material with 14% water, 5–7% OC, silt/clay, and weathered coal-tar, petroleum, soot and ash.
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified
Why convert CPDMS into chemical activity?
Via a separate calibration so results are activities of individual PAHs in the soil.
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified
What Danish soil criterion is cited for comparison?
Sum of four PAHs must not exceed 4 mg/kg dry soil.
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified
Why is activity more comparable than Csoil?
Soils are heterogeneous geosorbents; PDMS is a well-defined homogeneous phase.
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified
What r2 cutoff was required as an equilibrium criterion?
r2 > 0.90, necessary but not sufficient.
Source: Determining the chemical activity of hydrophobic organic compounds in soil using polymer coated vials · DOI · quote verified