Dispersive solid phase extraction headspace sampling in gas chromatography-mass spectrometric analysis of volatiles: Application to separation of polycyclic aromatic hydrocarbons

Abstract

For the first time, dispersive solid phase extraction combined with headspace sampling was introduced and applied to separation and pre-concentration of polycyclic aromatic hydrocarbons (PAHs) as representative of volatile and semi-volatile compounds, from aqueous solutions and sediments using multiwall carbon nanotubes (MWCNTs). After adsorption, PAHs were desorbed thermally from the surface of MWCNTs using a gas chromatography mass spectrometry (GC-MS) CombiPAL headspace device or a homemade thermal desorption system. Pre-concentration was maximized through optimization of solution pH, sorbent amount, and extraction time as well as desorption time and temperature of PAHs. The calibration curves were linear in the range 0.005-30 ng mL−1 for 13 PAHs at optimum conditions, with the coefficients of determination (R2) above 0.992, and detection limit in the range of 0.0021 to 0.0045 ng mL−1. Reproducibility for all PAHs was between 1.6 and 4.2%. Method recoveries were in the range of 94.0-102% for three spiked levels (1, 10, 20 ng mL−1). The methodology is even better if the selective or specific magnetic sorbent is used.