Environmentally-friendly and ultrasonic-assisted preparation of two-dimensional ultrathin Ni/Co-NO 3 layered double hydroxide nanosheet for micro solid-phase extraction of phenolic acids from fruit juices.

In this paper, we report an environmentally-friendly and low cost synthetic approach for large-scale fabrication of 2-dimentional porous Ni/Co-NO ₃ -based layered double hydroxide (Ni/Co-NO ₃ -LDH) nanosheet through ultrasonic-assisted process. The synthesis procedure used ethylene glycol/water system as an eco-friendly solvent system. The synthesized LDH was characterized by FE-SEM, TEM, XRD, and FT-IR techniques. FE-SEM and TEM images showed porous structure surface morphology of the synthesized LDH. Also, For Ni/Co-NO ₃ -LDH, a hexagonal ultrathin layered was obtained owing to ultrasonic irradiation and applied processing conditions. The prepared LDH was used as sorbent in dispersive micro solid-phase extraction procedure. Two phenolic acids including p-hydroxybenzoic acid and p-coumaric acid were selected as model compounds. Some experimental factors affecting the extraction efficiency of the analytes were investigated and optimized. Finally, the sorbent was used for the extraction of model compound from fruit juice samples followed by high performance liquid chromatography. Linear dynamic range of 0.5-500µgL ^-1 with a low detection limit (0.1µgL ^-1 ) was obtained by the method. The relative standard deviations were 2.5 and 4.3% for p-hydroxybenzoic acid and p-coumaric acid, respectively. All recoveries were between 82 and 92%.
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