Development and optimization of a vortex-assisted micro-solid phase extraction (VA-µSPE) method for sensitive...

In this work, an innovative CoNiCr-LDH@ND-COOH nanocomposite was synthesized and utilized as an efficient adsorbent for the effective extraction of fluoxetine. The nanocomposite structure combines the exceptional adsorption performance and capacity of carboxyl-functionalized nanodiamonds with the large surface area and tunable chemistry of layered double hydroxides (LDHs). The synthesized materials were characterized using FESEM, FESEM-EDX, FTIR, XRD, and BET analyses. These analyses demonstrated the nanocomposite's structural strength and surface characteristics. The developed extraction method was designed and optimized using Plackett-Burman and Central Composite Design methods. The optimal extraction conditions were as follows: 30 mg of adsorbent, pH 6.5, adsorption/desorption times of 5 minutes, ethanol as the eluent, and centrifugation at 4100 rpm. The method exhibited excellent analytical performance, with recoveries ranging from 87 to 99% at 225 nm (HPLC-DAD), a preconcentration factor of 50, a linear range of 1 to 5000 µg L^-1, a LOD of 0.25 µg L^-1, and a LOQ of 0.75 µg L^-1. The precision was acceptable, with intra- and inter-day RSD values of 4.8% and 6.7%, respectively. Furthermore, the adsorbent showed acceptable reusability for eight cycles. The presented method is robust, sensitive, and reusable for the extraction and determination of fluoxetine.