A nanoporous anodized alumina wire with a nanosized hydroxyapatite coating for headspace solid-phase microextraction of phenol and chlorophenols

We report on a new kind of fiber for solid-phase microextraction (SPME). It consists of a highly ordered nanoporous anodized alumina wire coated with nano-structured hydroxyapatite. A highly ordered nanoporous anodized alumina film was created on the aluminum wire by electrochemical anodization and then modified with nanostructured hydroxyapatite that was fabricated by a sol-gel approach from calcium nitrate and phosphoric acid. The resulting fiber was applied to the extraction of phenol as well as mono-, di- and trichlorophenols from aqueous samples prior to their determination by GC-MS. The effects of extraction temperature, extraction time, ionic strength, stirring rate, pH value as well as desorption temperature and time were studied. Under optimum conditions, the repeatability for one fiber (for n = 5), expressed as the relative standard deviation, is between 4.2 and 8.3 %. The detection limits are between 0.5 and 1.2 ng.mL(-1). The method is simple, fast, and inexpensive. The fibers are thermally stable and yield better recoveries than conventional methods of analysis.