Preparation and characterization of a novel nanocomposite coating based on sol-gel titania/hydroxyapatite for solid-phase microextraction

In this work a novel nanocomposite coating with high thermal stability and high durability is prepared. The surface of the stainless steel as a support was initially modified by (3-mercaptopropyl)trimethoxysilane. Surface characteristics of pure titania (TiO2), pure hydroxyapatite (HAP) and Hap/TiO2 nanocomposite coating were investigated and compared by energy dispersive X-ray (EDX) spectroscopy as well as by field emission-scanning electron microscopy (FESEM). The mutual effects of components on each other were discussed. Addition of HAP sol to the pure TiO2 sol, considerably changes the coating morphology. The applicability of the sol-gel HAP/TiO2 fiber was assessed for the headspace solid-phase microextraction (HS-SPME) of benzene, toluene, ethylbenzene and xylenes (BTEXs) from water sample followed by gas chromatography-mass spectrometry (GC-MS). Important parameters affecting the extraction efficiency were investigated. The efficiency of HAP/TiO2 nano-composite coating was compared with other reported fibers and showed very good results. Under optimal conditions, the detection limits (S/N = 3) were in the range of 0.04 to 1 mu g L-1, and the limits of quantification (S/N = 10) were between 0.1 and 4 mu g L-1. The relative standard deviations (RSDs) for each fiber (at 20 mu g L-1 and n = 5) were in the range of 1.76 to 8.18%, while the RSDs between fibers were 3.03 to 10.02%. The method showed a large linearity in the range from 0.1 to 1000 mu g L-1 with correlation coefficients of > 0.995.