Enrichment of phenolic compounds from water samples by using magnetic Fe3O4 nanoparticles coated with a Keggin type heteropoly acid of type H6[BFe(OH2)W11O39] as a sorbent

The paper describes a new sorbent referred to as BW11Fe which is a Keggin-type heteropolyacid of type H6[BFe(OH2)W11O39] supported on aminopropyl modified silica-coated magnetite nanoparticles (BW11Fe@APSCM-NPs). The sorbent combines the advantages of heteropoly acid and magnetic nanoparticles and possesses large capacity, good interactions with analytes, tunability of the active sites, rapid removal and easy separation of the solid phase. This makes it an excellent sorbent for extracting the phenolic compounds from water samples. Materials were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and FT-IR. The BW11Fe@APSCM-NPs were applied to the magnetic solid-phase extraction of phenolic compounds from water samples prior to their determination by gas chromatography with flame ionization detection. Under optimal conditions, the calibration plots for the phenols studied (phenol, 4-chlorophenol, o-cresol, m-cresol and 4-aminophenol) are linear in the range from 0.04 to 200 ngai...mL(-1). The method displays detection limits (at an S/N ratio of 3) that range between 0.01 and 0.2 ngai...mL(-1). The repeatability was investigated and gave relative standard deviations of < 7.5% (for n = 5). The method was successfully employed to the extraction of the phenolic compounds from water samples and recoveries are in the order of 90.1 to 99.4%.