Preparation and evaluation of a layered double hydroxide film on a nanoporous anodic aluminum oxide/aluminum wire as a highly thermal-resistant solid-phase microextraction fiber

A hierarchical ZnAl layered double hydroxide (ZnAl-LDH) framework has been fabricated via the in situ crystallization technique on a nonporous anodic aluminum oxide/aluminum wire (AAO/Al) as both the substrate and the aluminum source. The prepared wire with a high surface area and a uniform and compact structure was used as a solid phase microextraction (SPME) fiber for separation and determination of phenolic compounds from aqueous solutions in combination with gas chromatography-mass spectrometry (GC-MS). The fabricated LDH/AAO/AL wire displays flowerlike LDH microspheres composed of numerous LDH nanoplatelets, which was confirmed by the SEM image. The novel SPME fiber was evaluated for the extraction of some phenolic compounds (PCs) from water and wastewater sample solutions in combination with gas chromatography-mass spectrometry. A one at-a-time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, stirring rate, pH, ionic strength and desorption time and temperature. Under optimum conditions, the repeatability for one fiber (n = 3), expressed as relative standard deviation (R.S.D.%), was between 4.3% and 9.7% for the test compounds. The detection limits for the studied compounds were between 4 and 9 pg mL(-1). The developed method offers the advantage of being simple to use, with lower cost of equipment, shorter analysis time, thermal stability of the fiber and high relative recovery in comparison to conventional methods of analysis.