Development of dispersive solid phase extraction based on dissolvable Fe3O4-layered double hydroxide for high-performance liquid chromatographic determination of phenoxy acid herbicides in water samples

Herein, magnetic nanoparticle coated with zinc-aluminum layered double hydroxide was successfully synthesized and characterized. The nanocomposite was used as an effective adsorbent to extract three phenoxy acid herbicides in water samples prior to high performance liquid chromatography-ultraviolet detection. An interesting characteristic of this sorbent is that it dissolves under acidic solution (pH < 4). As a result, the elution step was unnecessary, and no organic solvent was used in whole extraction process. Influential extraction factors such as pH of solution, amount of sorbent, type and volume of acidic solution and vortex time were optimized. The method displays low limits of detection (0.1 - 0.2 ng mL(-1)), good linearity (0.5 - 200 ng mL(-1)), acceptable precision (relative standard deviations were less than 9.3%) and accuracy (98.9-106.1%). Therefore, the method is sensitive, fast, eco-friendly, and suitable for determination of phenoxy acid herbicides in water samples.