Air/polymer distribution coefficients for polycyclic aromatic hydrocarbons by solid-phase microextraction sampling

Area of Science:

• Analytical Chemistry
• Environmental Science
• Materials Science

Background:

• Accurate determination of distribution coefficients (K) is crucial for quantifying polycyclic aromatic hydrocarbons (PAHs).
• Poly(dimethylsiloxane) (PDMS) coatings are widely used in solid-phase microextraction (SPME) for environmental analysis.
• Existing methods for K determination can be complex and require extensive calibration.

Purpose of the Study:

• To present two novel methods for estimating air-PDMS distribution coefficients (K) for low molecular weight PAHs.
• To validate these methods using a static calibration system (SCS) and gas chromatography-mass spectrometry (GC-MS).
• To offer a calibration-free approach for estimating K values.

Main Methods:

• Estimation of distribution coefficients (K) using a developed static calibration system (SCS) based on equilibrium theory.
• Estimation of K values utilizing a linear relationship between log K and linear temperature-programmed retention indexes (LTPRI).
• Analysis performed on a gas chromatography-mass spectrometry (GC-MS) system.

Main Results:

• Log K values ranged from 5.2 (naphthalene) to 8.9 (pyrene) at 22°C for both methods.
• Static calibration yielded a relative standard deviation (R.S.D.) of log K no more than 5.3%.
• LTPRI method demonstrated R.S.D. of retention times not exceeding 0.28% for repeated injections.

Conclusions:

• Both presented methods accurately estimate air-PDMS distribution coefficients for PAHs.
• The LTPRI method offers a rapid, calibration-free alternative for K estimation.
• These methods enhance the reliability and efficiency of PAH analysis in environmental samples.