Efficient analysis of polycyclic aromatic hydrocarbons by dispersive-µ-solid-phase extraction using silica-based nanostructured sorbent phases coupled to gas chromatography-mass spectrometry

Abstract

In this study, SBA-15 mesoporous silica has been investigated as sorbent phase for the extraction and determination of 10 polycyclic aromatic hydrocarbons (PAHs) in environmental water samples for the first time. The extraction step was performed through a dispersive-µ-solid-phase extraction (D-µ-SPE) followed by gas chromatography coupled to mass spectrometry (GC-MS). In particular, the surface of SBA-15 was chemically bonded to different functional groups (aminopropyl, phenyl, octyl and octadecyl), and the extraction efficiency of each sorbent phase was investigated. The sorbent phase was synthesized and characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), N₂ sorption analysis (Brunauer–Emmett–Teller), and thermogravimetric analysis (TGA). The optimized extraction conditions consisted of using 2 mg of the sorbent SBA-15/C8, 2 mL of sample, 2 min of vortex, 4 min of stirring in orbital shaker and 1 min of centrifugation; the desorption step was performed with 25 µL of ACN:acetone (50:50 v/v), vortex for 2 min, 8 min of stirring in orbital shaker and 3 min of centrifugation. The proposed method was validated, with determination coefficients higher than 0.99 for all analytes; LODs and LOQs ranged from 0.15 to 3.03 μg L⁻¹ and from 0.5 to 10.0 μg L⁻¹, respectively; intraday precision ranged from 2.6 to 12.1%; interday precision varied from 4.5 to 25.3%; and accuracy ranged from 92.0 to 112.3 %. This methodology was successfully applied for the analysis of eight groundwater samples from monitoring wells of gas stations in São Paulo. Moreover, according to AGREEprep metrics, the proposed method can be considered sustainable according to the concepts of green analytical chemistry.