Determination of poly(dimethyl)siloxane-water partition coefficients for selected hydrophobic organic chemicals using 14C-labeled analogs.
Aqueous solutions of (14)C-labeled analogs of seven hydrophobic organic chemicals (HOCs) were subject to solid-phase microextraction (SPME) under static conditions to assess their multi-compartment distribution and to compare poly(dimethyl)siloxane (PDMS)-water partition coefficients (K(f) values) with previously reported values. To accomplish this, a protocol for quantitative desorption of radiolabelled HOCs from SPME fibers using hexane was developed. Time series extractions indicated that loading of SPME fibers had reached steady-state by day 8 for PCBs 52, 77 and 153, phenanthrene, benzo[a]pyrene, p,p'-DDT and p,p'-DDE. The recovery of spiked radioactivity among the (residual) aqueous phase, the PDMS coating, and all remaining wetted experimental surfaces ranged between 80 and 120%. K(f) values based on (14)C-labeled analogs were in good agreement with previously published values that were determined at (or closely approaching) equilibrium conditions and without significant chemical depletion and/or uncorrected system losses. Because it allows for the direct determination of HOCs associated with the residual aqueous and experimental surface compartments, the use of radiolabelled HOC analogs is a powerful tool in discriminating among competing sorptive compartments encountered in most SPME fiber calibration methodologies employed to date.
Yang
Ze-Yu
ZY
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Greenstein
Darrin
D
Zeng
Eddy Y
EY
Maruya
Keith A
KA
D002250:Carbon Radioisotopes; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D009930:Organic Chemicals / Q000032:analysis / Q000737:chemistry*; D015203:Reproducibility of Results; D052617:Solid Phase Microextraction; D014867:Water / Q000737:chemistry*
D002250:Carbon Radioisotopes; D004129:Dimethylpolysiloxanes; D009930:Organic Chemicals; D014867:Water