Mahboobeh Morshedloo - Department of Chemistry, Faculty of Sciences, Islamic Azad University of Quchan, Iran
Mohamadreza Abedi - Department of Chemistry, Faculty of Sciences, Islamic Azad University of Quchan, Iran
Amir Hassan Amiri - Department of Chemistry, Faculty of Sciences, Hakim Sabzevari University, Sabzevar, Iran

The aim of this research is to develop the preconcentration and sample preparation method,based on solid-phase microextraction (SPME) procedure prior to gas chromatography-flameionization detector (GC–FID). In this research, the sol–gel method was applied for thepreparation of solid phase microextraction fibers to extract ethyl benzene and orthoxylene fromenvironmental water and biological samples. This thesis consists of four chapters. In the firstone, some of the sample preparation methods were reviewed. In the second part, someinformation about BTEX and in third part, informations about titanium dioxide nanotube hasbeen mentioned. And final section is experimental section. In the experimental section, thedeveloped PDMS-TNTs sol–gel coating was used to determine ethyl benzene and orthoxylene inreal water samples with GC-FID. This fiber demonstrated many inherent advantages, the mainone being the strong anchoring of the coating to the fused silica resulting from chemical bondingwith the silanol groups on the fused-silica fiber surface. The new PDMS-TNTs sol–gel fiber issimple to prepare, robust, with high thermal stability and long lifetime. Important parametersinfluencing the extraction efficiency such as desorption temperature and time, extractiontemperature, extraction time, stirring speed and salt effect were investigated and optimized.Under the optimal conditions, the method detection limits (S/N=3) were in the range of 0.6–3 pgmL–1 and the limits of quantification (S/N=10) between 2–10 pg mL–1. The relative standarddeviations (RSDs) for one fiber (repeatability) (n=5) were obtained from 4.4 up to 5.7%. Thedeveloped method was successfully applied to real water samples while the relative recoverypercentages obtained for the spiked water samples at 20 μg mL–1 were from 90.2 to 101.9%.

solid-phase microextraction, TiO2 nanotubes, sol-gel technology, BTEX, Water samples