A hydrophobic deep eutectic solvent mediated sol-gel coating of solid phase microextraction fiber for determination of toluene, ethylbenzene and o-xylene in water coupled with GC-FID

As a new type of green solvents, deep eutectic solvents (DESs) are attracting more and more attentions due to their unique properties and cheapness. However, most DESs reported previously were hydrophilic and thus limiting their applications in aqueous medium. In this study, a novel hydrophobic DES was prepared by mixing ethylparaben and methyl trioctyl ammonium chloride, and density, viscosity, and contact angle of the DES were determined to character its solvent characteristics. Then, this DES was used as an efficient additive of sol-gel sorbent coating of poly(dimethylsiloxane) (PDMS) fiber. It was found that the addition of hydrophobic DES could generate a lot of neat pores in the PDMS fiber surface, thus significantly improving the performance of PDMS fiber coating. The feasibility of PDMS-DES adopted for head space solid phase microextraction was evaluated by GC-FID for the extraction and determination of volatile organic compounds, such as toluene, ethylbenzene and o-xylene. Key parameters affecting the extraction efficiency were investigated systematically. Under optimal conditions, the linear range with PDMS-DES fiber lied between 10 and 1000 mu g L-1, and the limit of detection (LOD) was in the range from 0.005 to 0.025 mu g L-1. Compared with homemade PDMS fiber, the peak area of signal response for the PDMS-DES fiber was 3 times higher. At the same time, the LOD for the proposed method was much lower than the commercial 100 mu m-PDMS fiber coating.