Magnetic Janus nanofibrous composite membrane for green microextraction of BTEX from environmental samples

Benzene, toluene, ethylbenzene, and xylene isomers (BTEX) are prominent pollutants of concern due to their adverse health effects and ubiquitous presence in environmental matrices. In this study, an innovative Janus nanocomposite membrane was developed, comprising a polyamide/microcrystalline cellulose/nickel-aluminum layered double hydroxide (PA6/LDH/MCC) active layer electrospun onto a polyurethane (PU) nanofibrous support. The asymmetric Janus architecture was characterized via Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Iinfrared Sspectroscopy (FT-IR), X-ray Diffraction (XRD), and nitrogen adsorption-desorption isotherms. The membrane was successfully utilized as a sorbent in membrane-based solid-phase microextraction (M-SPME) for the enrichment of BTEX, followed by gas chromatography-mass spectrometry (GC-MS) analysis. Matrix-matched calibration demonstrated a linearity of 10-10000 μg/L (r²: 0.9926-0.9954), with limits of detection between 0.09 and 0.45 μg/L and reproducibility (RSDs) of 2.5-7.0%. The enrichment factors were between 14.8 and 23.8. The method's practical applicability was validated in urban air, water, and soil samples, yielding satisfactory recovery rates (70-110%). Furthermore, the sorbent exhibited excellent stability, maintaining over 90% efficiency after seven cycles. The sustainability of the proposed method was quantitatively assessed using Analytical Greenness Metric for Sample Preparation (AGREEprep, score: 0.43) and the Blue Applicability Grade Index (BAGI: 67.5), confirming its high degree of environmental compatibility and practical laboratory utility.