Facile preparation of poly ortho-cresol doped nanotitania for solid-phasemicroextraction of dialkyl phthalate esters in bottled waters

A robust, highly efficient and sensitive analytical technique involving solid-phase microextraction (SPME) coupled to gas chromatography (GC) was successfully established to determine four dialkyl phthalate esters in aquatic samples. In this research, poly ortho-cresol/TiO۲ nanocomposite coating was made by direct electropolymerization of poly ortho-cresol and TiO۲ nanoparticles and evaluated as a novel direct immersion SPME fiber coating. The functionalized fiber is mechanically and chemically stable and can be easily prepared in a highly reproducible manner. The effects of the monomer and TiO۲ concentration, polymerization voltage and polymerization time on the fiber were discussed in details. Under the optimized conditions, characterization of the nanocomposite was investigated by energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Surface morphological and compositional analyses revealed that the composite coating of poly ortho-cresol uniformly doped with TiO۲ nanoparticles. The factors related to the solid-phase microextraction method such as desorption temperature and time, extraction temperature and time, and ionic strength were also tested. The as-fabricated fiber exhibited good extraction capability for phthalate compounds in combination with GC. At the optimum SPME conditions, The obtained limits of detection was in the range between ۰.۰۰۳ and ۰.۰۰۶ ng mL-۱. Relative standard deviations in terms of intra-day and inter-day by five replicate analyses from aqueous solutions containing ۰.۱ ng mL-۱ of target analytes were below ۵.۸% and ۸.۲%, respectively. Thus, this fiber was used for extraction of phthalates from commercial PET bottled water samples.

Keywords:

Dialkyl phthalate esters , TiO۲ Nanocomposite , Solid-phase microextraction , PET bottles