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Determination of polydimethylsiloxane-air partition coefficients using headspace sorptive extraction
Nathalie De Coensel1, Koen Desmet, Tadeusz Górecki
1Laboratory of Separation Science, Department of Organic Chemistry, Ghent University, Krijgslaan 281 S4, B-9000 Gent, Belgium.
Journal of Chromatography. A
|November 14, 2006
Summary
Polydimethylsiloxane-air partition coefficients were determined for moth repellents. These coefficients correlate with octanol-air values, aiding in extraction efficiency estimations for environmental monitoring.
Area of Science:
- Environmental Chemistry
- Analytical Chemistry
- Material Science
Background:
- Polydimethylsiloxane (PDMS) is widely used for analyzing volatile organic compounds.
- Understanding PDMS-air partition coefficients (K(PDMS-A)) is crucial for accurate air monitoring.
- Compounds like p-dichlorobenzene, naphthalene, and camphor sublimate and are relevant environmental analytes.
Purpose of the Study:
- To determine K(PDMS-A) for specific sublimating compounds.
- To investigate the relationship between K(PDMS-A) and octanol-air partition coefficients (K(OA)).
- To assess the influence of temperature and concentration on K(PDMS-A) values.
Main Methods:
- Direct headspace analysis and headspace sorptive extraction (HSSE) using PDMS-coated stir bars.
- Equilibrium measurements of air and PDMS concentrations for p-dichlorobenzene, naphthalene, and camphor.
- Temperature-dependent measurements and analysis at varying analyte concentrations.
Main Results:
- K(PDMS-A) values were successfully determined for the selected compounds.
- A strong proportionality was observed between K(PDMS-A) and K(OA).
- Partition coefficients increased with decreasing temperature and were concentration-dependent, especially at high values.
Conclusions:
- K(OA) can effectively estimate PDMS extraction efficiency for these compounds in air.
- K(PDMS-A) values can be used to estimate K(OA) for organic compounds.
- Caution is advised when applying K(PDMS-A) from high concentrations to low concentrations, particularly for compounds with large partition coefficients.
