Functionalized polythiophene-coated magnetic nanoparticles for solid-phase extraction of phthalates / Siti Nor Atika Baharin

Siti Nor Atika , Baharin (2016) Functionalized polythiophene-coated magnetic nanoparticles for solid-phase extraction of phthalates / Siti Nor Atika Baharin. PhD thesis, University of Malaya.

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Abstract

Polythiophene, poly(3-hexylthiophene), poly(N-phenyl-1-(2-thienyl)methanimine) and poly(phenyl-(4-(6-thiophen-3-yl-hexyloxy)-benzylidine)amine) were successfully coated on the surface of Fe3O4 magnetic nanoparticles (MNP). Two of the functionalized monomers, N-phenyl-1-(2-thienyl)methanimine and phenyl(4-(6- thiophen-3-yl-hexyloxy)-benzylidine)amine were successfully synthesized. Characterization by FT-IR, TGA, XRD, VSM and BET confirmed the coating has taken place. Further characterization of MNP coated poly(phenyl-(4-(6-thiophen-3- yl-hexyloxy)-benzylidine)amine) (P3TArH) was conducted using TEM and FESEM. Among those nanocomposites, MNP coated P3TArH has shown higher determination capabilities of phthalates. The adsorption behaviour of di(2- ethylhexyl) phthalate (DEHP) onto the MNP coated P3TArH showed fast kinetics, occurred heterogenously on the adsorption sites and exothermic. The activation energy determined found was -40.6 kJ mol−1 K−1, indicated the process is physisorption. The successful synthesised magnetic nanoparticles were further optimized for magnetic solid-phase extraction (MSPE) of environmental samples. Separation and determination of the extracted phthalates namely dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), dicyclohexyl phthalate (DCP), di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DNOP) were conducted by gas chromatography-flame ionization detector (GC-FID). The best working conditions were as follows; sample at pH 7, 30 min extraction time, ethyl acetate as elution solvent, 500 μL elution solvent volumes, 10 min desorption time, 10 mg adsorbent dosage, 20 mL sample loading volume and 15 g L-1 concentration of NaCl. Under the optimized conditions, the analytical performances were determined with linear range of 0.1-50 μg L-1 and limit of detection at 0.054-0.468 μg L-1 for all the studied analytes. The intra-day (n=7) and inter-day (n=3) relative standard deviations, RSD (%) of three replicates each demonstrated in the range of 3.7-4.9 and 3.0-5.0 respectively. The steadiness and reusability studies suggested that the MNP@P3TArH could be used up to five cycles. The proposed method was executed to analysis of real water samples namely commercial bottled mineral waters and fresh milk and recoveries in the range of 68-101 % and relative standard deviation (RSD %) lower than 7.7 % were attained.

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