o-xylene and m-xylene along with sodium chloride were
purchased from Merck (Darmstadt, Germany). Standard solution
(1000mg L1) of VOC mixture was prepared in HPLC-grade
methanol (Merck) and stored in the refrigerator. The working
standard solutions were prepared weekly by diluting the standard
solution with methanol, and more diluted working solutions were
prepared daily by diluting this solution with double distilled water
(DDW). Polybutylene terephthalate (PBT) was purchased from
Kolon Industries Inc. (Seoul, Korea) and triflouroaceticacid (TFA)
were obtained from Riedel-de Haën (Seelze-Hannover, Germany).
The NiO nanoparticles with diameters of 12–50nm were obtained
from Degussa Company (Darmstadt, Germany).