Hollow Polymer Nanospheres and Fe3O4@TFPA-Bd-COF as a Mixture Adsorbent in Microextraction by Packed Sorbent for Extraction of BTEX Biomarkers in Urine

A new and fast sample preparation method was developed to extract Hippuric acid (HA), Trans,trans-muconic acid (tt-MA), Mandelic acid (MA), and m-Methylhippuric acid (m-MHA) in urine samples using Hollow polymer nanospheres (HPSs), Covalent organic frameworks (COFs), and their mixture (HPS:COF) as an adsorbent, combined with high-performance liquid chromatography-ultraviolet spectrophotometry (HPLC-UV). X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to study the features of the adsorbents. The effect of important factors such as temperature and pH of the sample, amount of sorbent, conditioning and washing solvents, type and volume of desorption solvent, sample volume, and the number of extraction cycles were investigated to achieve the optimal conditions with microextraction by packed sorbent (MEPS) procedure. The applicability of the proposed method was then validated in the laboratory. Finally, the target analytes in the urinary samples of gas station workers were examined. The data analysis showed that using an HPS:COF mixture improves the extraction efficiency in optimal conditions compared to the case where the COF adsorbent is used alone (extraction efficiency, 81-87.5%). Also, a good linear dynamic range (0.1-1000 µg/mL for m-MHA), a low detection limit (0.02 µg/mL for tt-MA), and acceptable intra-day and inter-day precision (1.4-3.6 % and 4.5-8.9 %, respectively) were obtained under similar conditions. Overall, HPS: COF-MEPS exhibited excellent extraction efficiency (85.4-93.3%) and has the potential to replace previous methods in the biomonitoring of BTEX biomarkers in urine.