Synthesis, characterization and implementation of 3D nanoscale epoxy–polyhedral oligomeric silsesquioxanes network for isolation of polycyclic aromatic hydrocarbons in tea and coffee

Polyhedral oligomeric silsesquioxanes (POSSs) are 3D nanoscale structures[1] with fascinating potential to be used as extractive phases in solid phase microextraction (SPME). Here, as a case study, the octaglycidyldimethylsilyl polyhedral oligomeric silsesquioxane (POSS–epoxy) network was fabricated on a stainless steel wire via sol–gel methodology and used as a SPME fiber coating. The uniform pore structure, high surface area, and hydrophobicity of POSS–epoxy[2], make it susceptible toward isolation of non– to semi–polar compounds. Performance of the POSS–epoxy fiber coating was examined considering three classes of typical environmental pollutants including chlorobenzenes (CBs), benzene derivatives (benzene, toluene, ethylbenzene, xylen (BTEX)) and polycyclic aromatic hydrocarbons (PAHs) and acceptable extraction efficiencies were achieved. The effects of various types of sol–gel precursors in the fabrication of fiber coatings were investigated. Also, extraction capability of the POSS–epoxy was compared with some commercial fibers such as polydimethyl siloxane divinyl benzene (PDMS–DVB) were obtained. All the influencing parameters affecting the headspace (HS) analysis and gas chromatography (GC) procedure were investigated and optimized. The POSS–epoxy fiber was applied to develop a HS–SPME–GC–MS method for quantification of PAHs, as model analytes, in tea, coffee and some other environmental water–based real samples. The extractive–phase was found to be very sensitive for determination of PAHs with reliable figures of merit such as acceptable linearity (1–200 ng L-1), low limits of detection (LODs), 0.1–0.3 ng L-1, suitable intra–day relative standard deviation (RSD% 10 %) and inter–day (RSD% 12 %), and long lifespan (number of uses 200 times).