Applied Water Science. Группа авторов

waters (25 mL) m-dSPE using 30 mg poly(1-vinyl-3-butylimidazolium bromide)-PS m-NPs under vortex for 2.5 min, a magnet was used for decantation, and elution with 7 mL ACN by sonication HPLC-DAD 0.017-0.047 μg/L 77.8-102.1% at 2 and 20 μg/L One sample of each water were analyzed and residues of DEP were found at 25.8 and 15.5 μg/L in the carbonate and soda waters, respectively ACN showed higher extraction efficiency than acetone, petroleum ether and MeOH as elution solvent [82] DMP, DEP, DAP, DIBP, and DBP Tap and well waters (5 mL plus 15% w/v NaCl) m-dSPE using 15 mg Fe₃O₄-MIL-101(Cr) MOF under agitation for 20 min, a magnet was used for decantation, and elution with 1 mL hexane/acetone (1:1 v/v) by vortex for 3 min GC-MS 0.3–0.5 μg/L 90.1–106.7% at 5 and 50 μg/L One sample of each water were analyzed and no residues were detected The use of Fe₃O₄-MIL-101(Cr) MOF showed higher enrichment capacity than Fe₃O₄ and MIL-101(Cr) MOF separately. Hexane/acetone (1:1 v/v) showed higher extraction efficiency than ethyl acetate, hexane, acetone and hexane/ethyl acetate (1:1 v/v) as elution solvent. Human plasma was also analyzed [86] DMP, DEP, DBP, BBP, DEHP, and DNOP Tap, drinking and mineral waters (10 mL) m-dSPE using 15 mg Fe₃O₄-MIL-100 MOF and 15-mg Fe₃O₄-SiO₂-polythiophene under sonication for 1 min and oscillation for 15 min, a magnet was used for decantation, and elution with 1 mL ACN by agitation for 10 min GC-MS 1.1–2.9 μg/L 76.9–109.1% at 1, 10 and 50 μg/L One sample of each water were analyzed and no residues were quantified A combination of 15-mg Fe₃O₄-MIL-100 MOF and 15-mg Fe₃O₄-SiO₂-polythiophene gave better extraction efficiency than using 30-mg each separately. ACN showed higher extraction efficiency than acetone, ethyl acetate and hexane as elution solvent [88] DMP, DBP, BBP, DCHP, and DEHP Tap and lake waters (100 mL adjusted at pH 6) m-dSPE using 30 mg poly(1-vinylimidazole)-carboxy-latocalix[4] arene m-NPs under sonication for 15 min, a magnet was used for decantation, and elution with 0.5 mL MeOH by sonication for 5 min HPLC-UV 0.05–0.11 μg/L 89.9–110.0% at 0.5, 1, and 5 μg/L One sample of each water were analyzed and contained at least 1 PAE at levels from 0.4 to 8.9 μg/L Methanol showed higher extraction efficiency than ACN and chloroform as elution solvent. The use of poly(1 -vinylimidazole)-carboxy-latocalix[4] arene m-NPs showed higher enrichment capacity than Fe₃O₄ and poly(1-vinylimidazole) separately. m-dSPE using poly(1-vinylimidazole)-carboxy-latocalix[4] arene m-NPs showed better results compared with SPE with C₁₈ and Cleanert SCX cartridges. Drinks, tonic lotions, and human serum were also analyzed [83] DBP, DMP, DCHP, BBP, and DEP River water (10 mL) m-dSPE using 30 mg 3D N-Co-C/HCF MOF under agitation for 20 min, a magnet was used for decantation, and elution with 6 mL ACN by sonication for 10 min HPLC-UV 0.077–0.377 μg/L 92.4–104.2% at 1, 10, and 50 μg/L One sample was analyzed and contained DMP and DEP at 0.075 and 0.081 μg/L, respectively Green tea, sports beverage and white spirit were also analyzed. ACN showed higher extraction efficiency than acetone, MeOH, and ethanol as elution solvent [87] DPP, DBP, DCHP, DEHP, DNOP, DIDP, BBP, DINP, DIPP, DNPP, and DEHA Sea water (50 mL adjusted at pH 6) m-dSPE using 120 mg Fe₃O₄-PDA under agitation for 1 min, a magnet was used for decantation, and elution with 1 mL dichloromethane by agitation for 30 s GC-MS 0.0018–0.319 μg/L 79–116% at 0.4, 1, and 1.6 μg/L Ten samples were analyzed and no residues were quantified Sea sand was also analyzed. [80]

      MeOHMeOHMeOHMeOHMeOHACN, acetonitrile; BBP, benzylbutyl phthalate; BMPP, bis(4-methyl-2-pentyl) phthalate; DAD, diode-array detector; DAP, diallyl phthalate; DBEP, di(2-butoxyethyl) phthalate; DBP, dibutyl phthalate; DCHP, dicyclohexyl phthalate; DEEP, di(2-ethoxyethyl) phthalate; DEHA, di(2-ethylhexyl) adipate; DEHP, di(2-ethylhexyl) phthalate; DEP, diethyl phthalate; DHP, diheptyl phthalate; DHXP, dihexyl phthalate; DIBP, diisobutyl phthalate; DIDP, diisodecyl phthalate; DINP, diisononyl phthalate; DIPP, diisopentyl phthalate; DMEP, di(2-methoxyethyl) phthalate; DMIMs, dummy molecularly imprinted microbeads; DMP, dimethyl phthalate; DNOP, di-n-octyl phthalate; DNP, dinonyl phthalate; DNPP, di-n-pentyl phthalate; DPhP, diphenyl phthalate; DPP, dipropyl phthalate; dSPE, dispersive solid-phase extraction; G, graphene; GC, gas chromatography; GO, graphene oxide; HCF, hierarchical carbon framework; HPLC, high-performance liquid chromatography; LOQ, limit of quantification; m-dSPE, magnetic solid-phase extraction; MeOH, methanol; MIL, Material of Institute Lavoisier; MIP, molecularly imprinted polymer; m-NPs, magnetic nanoparticles; MOF, metal organic framework; MS/MS, tandem mass spectrometry; MS, mass spectrometry; MWCNTs, multiwalled carbon nanotubes; PAE, phthalic acid ester; PDA, poly(dopamine); PS, polystyrene; SPE, solid-phase extraction; UV, ultraviolet; ZIF, Zeolitic Imidazolate Framework.

      MeOHMeOHMeOHMeOHMeOH

      Figure 1.5 Scheme of a similar extraction procedure carried out by Chen et al. [75] using the same (β-CD-PNIPAM temperature-sensitive polymer as extractant for the determination of phenolic compounds in river water samples. Reprinted from [75] with permission of Elsevier. Peak identification: phenol (BP), 2,4-dichlorophenol (2,4-DCP), (β-naphthol ((β-NP), and bisphenol A (BPA).

Despite the simplicity of the dSPE, the whole procedure can be even improved and simplified if the sorbent particles can be manipulated with a magnet. Such dSPE mode is called m-dSPE and is based on the use of magnetic NPs (m-NPs), which can be applied as synthesized (though in very few cases), although they are generally functionalized or coated with other chemical species or materials, resulting in many cases a “coreshell” structure, in order to improve their selectivity, or even embedded them in the extraction sorbent to provide it with magnetic properties [50]. Despite the extraction step is performed in a similar way as in dSPE, in this case, the magnetic sorbent containing the analytes is retained in the extraction recipient using an external magnet while the sample matrix is easily discarded without the need of an additional centrifugation step or the retention of the sorbent in an empty column. Finally, the analytes are desorbed from the magnetic sorbent using a suitable solvent and, once more, the sorbent is retained with the magnet to separate the solvent containing the analytes by decantation for their determination with a suitable technique.

Although a wide variety of metals, metal oxides and alloys can be used to provide magnetic properties to the sorbent, Fe₃O₄