New poly(ethylene glycol) solid-phase microextraction fiber employing zirconium oxide electrolytically deposited onto a NiTi alloy as substrate for sol-gel reactions

In this study zirconium oxide electrolytically deposited onto a NiTi alloy (NiTi-ZrO2) was employed as a new substrate forsol-gel reactions for the fabrication of an efficient and unbreakable solid-phase microextraction fiber. The NiTi-ZrO2 surface was activated and used as a substrate for coating with poly(ethylene glycol) sol solution. Fibers produced with and without a ZrO2 layer were compared and, through scanning electron micrographs, an excellent attachment of the polymer in the case of the NiTi-ZrO2 substrate was demonstrated. The proposed fiber showed excellent thermal stability up to the maximum temperature evaluated of 320 degrees C, suggesting a strong interaction between the substrate surface and the polymeric coating, probably due to chemical bonding. The applicability of the proposed fiber was evaluated through extraction of halophenols and phthalate esters from the headspace and directly from aqueous sample, respectively. Some parameters affecting the extraction efficiency were optimized by full-factorial and Doehlert experimental designs, and the analytical features were estimated. Detection limits in the range of 1.2-9.8 ng L-1 for halophenols and 0.3-0.7 mu g L-1 for phthalate esters were obtained. Repeatability for one fiber (n = 6) was in the range of 4.6-10.6% and fiber-to-fiber reproducibility (n = 5) was lower than 12% for all compounds. The results suggest that the proposed fiber can be successfully applied for the determination of these compounds in water and also can be extended to other analytes and matrices. (c) 2008 Elsevier B.V. All rights reserved.