A high-surface-area mesoporous carbon synthesized using porous hydroxyapatite nanostructures template: an efficient adsorbent for solid-phase extraction of parabens.

Herein, a mesoporous carbon material was prepared via pyrolysis of a melamine-resorcinol formaldehyde copolymer synthesized in the presence of mesoporous hydroxyapatite (HA) nanostructures, as a hard template. The porous HA nanostructures were prepared through a novel strategy that involved synthesizing calcium carbonate nanostructures on CTAB micellar aggregations as a soft template, followed by carbonate-phosphate replacement under hydrothermal conditions. This approach yielded microspheres composed of rod-like nanostructures featuring ordered approximately 1 nm nanochannels, exhibiting a BET surface area of 51.17 m2 g-1 and a BJH-derived characteristic pore diameter of 18.46 nm. The XRD analysis of the carbon product indicated the presence of a graphitic carbon structure, consistent with the Raman spectroscopy results. Additionally, the presence of oxygen and nitrogen heteroatoms and their related functional groups in the carbon framework was confirmed by elemental analysis and FT-IR spectroscopy. Based on BET analysis, the carbon product exhibited a high specific surface area of 882.78 m2 g-1, a large pore volume of 3.944 cm3 g-1, and a characteristic pore diameter of 32.58 nm obtained from BJH analysis. BET analysis highlighted the role of CTAB and carbonate in the synthesis of the HA template, enabling the achievement of high-surface-area mesoporous carbon. The combination of high porosity, graphitic domains, and oxygen- and nitrogen-containing species makes the material a promising adsorbent for the extraction of relatively polar aromatic compounds. The synthesized carbon material was employed as an effective adsorbent for the dispersive solid-phase extraction (SPE) of some parabens, preservatives with endocrine-disrupting effects, with detection using HPLC-UV. The experimental design methodology efficiently determined optimal extraction conditions while minimizing the number of experiments and analyzing parameter interactions. Under the optimized conditions, a good analytical performance for the proposed method was achieved with a linearity of 0.1-100.0 μg L-1 (R2 ≥ 0.998) and preconcentration factors ranging from 84 to 116 for the target analytes. The applicability of the proposed method was assayed in real samples with different matrices, yielding satisfactory relative recoveries (89-111%) and RSD values (n = 3) ranging from 2.4% to 7.9%.