Solid-phase microextraction of phthalate esters from aqueous media by electrophoretically deposited TiO2 nanoparticles on a stainless steel fiber

A novel SPME fiber was prepared by electrophoretic deposition of titanium dioxide nanoparticles (nano-TiO2) on a stainless steel wire. It was used in the direct immersion solid-phase microextraction (DI-SPME) of four phthalate esters from aqueous samples prior to gas chromatographic (GC) analysis. The effects of various parameters on the efficiency of the SPME process such as the mode of extraction, extraction temperature, film thickness of the SPME fiber, salt content, extraction time and stirring rate were investigated. The comparison of the fiber with another homemade poly(3,4-ethylenedioxythiophene)-TiO2 (PEDOT-TiO2) nanocomposite fiber and a commercial polydimethylsiloxane (PDMS) fiber showed the better extraction efficiency of the nano-TiO2 fiber for phthalate esters. Under optimized conditions, the limit of detection (LOD) for the phthalate esters varied between 0.05 and 0.12 μg L−1. The inter-day and intra-day relative standard deviations for various phthalate esters at 10 μg L−1 concentration level (n = 6) using a single fiber were 6.6–7.5% and 8.3–11.1%, respectively. The fiber to fiber repeatabilities (n = 4), expressed as relative standard deviation (RSD%), were between 8.9% and 10.2% at 10 μg L−1 concentration level. The linear ranges varied between 0.5 and 1000 μg L−1. The method was successfully applied to the analysis of the bottled mineral water sample with recoveries from 86 to 107%.