Surface-functionalized magnetic cellulose nanoparticles for green magnetic dispersive solid-phase extraction of bisphenol a from human blood followed by high-performance liquid chromatography with diode-array detection

A green, fast and sensitive analytical method was developed for the determination of bisphenol A (BPA) in human blood, combining magnetic dispersive solid-phase extraction (MDSPE) on surface-functionalized magnetic cellulose nanoparticles (MCNPs) with high-performance liquid chromatography and diode-array detection (HPLC-DAD). The MCNPs were fabricated via immobilization of an iron/cobalt oxide/oxyhydroxide phase on microcrystalline cellulose. The network of renewable cellulose endows the nanomaterial with hydrophilic character, biocompatibility and availability of numerous surface hydroxyl groups, allowing the retention of BPA via hydrogen bonding and hydrophobic interaction while ensuring fast magnetic separation. Important parameters of extraction such as sample pH, sorbent mass, extraction duration, type and volume of eluent, and ionic strength were optimized. Density functional theory (DFT) calculations showed that BPA binds to the cellulose matrix through cooperative hydrogen bonding and dispersion-driven CH/OH-π interactions. The developed analytical approach showed good linearity over the concentration range of 0.5-500 ng mL^-1 (R² = 0.9993), a limit of detection of 0.15 ng mL^-1, a limit of quantitation of 0.50 ng mL^-1 and an enrichment factor of 18.4. The intra-day and inter-day precisions were no >2.4 % and 4.1 % (RSD), respectively, and the relative recoveries from blood samples enriched with BPA were between 92.9 % and 102.4 %. The validated technique was used for analysis of 30 residual blood samples remaining after routine clinical analyses, and total BPA concentration was quantified in 26 out of 30 samples (0.58-8.18 ng mL^-1, median 2.22 ng mL^-1). The environmentally friendly character of the method was proven by the AGREE score of 0.81. The proposed sorbent is inexpensive, biodegradable and reusable for at least seven cycles, offering a sustainable alternative to conventional sorbents for routine biomonitoring of BPA. Although magnetic cellulose of this type has been reported previously, the novelty of this work lies in its use, to our knowledge for the first time and without any ionic-liquid, framework or polymer modification, for the determination of total (deconjugated) BPA in human blood, supported by a DFT description of the retention mechanism and by a dedicated evaluation of selectivity, anti-interference ability and stability.