Zinc Oxide Nanorod- Magnetized Silica Aerogel as a New Composite in Solid Phase Extraction for Phthalate Esters Detection: Optimization by Response Surface Methodology

In this study, the application of Zinc oxide nano-rod decorated on magnetic silica aerogel as an adsorbent for the dispersive solid-phase extraction (DSPE) of phthalate esters in urine samples was investigated. First, Fe₃O₄ nanoparticles were decorated into the silica aerogel matrix to fabricate magnetic silica aerogel. Afterword, zinc oxide nano-rods (ZnR) were grown up onto the magnetic silica aerogel to prepare ZnR@Si@Fe₃O₄. The nano-composite was used for pre-concentration three phthalate esters, dimethyl phthalates, diethyl phthalate and diethyl hexyl phthalate, before analysis using GC-FID. Optimum extraction conditions were determined using the response surface method, pH 7.6, adsorbent dose 30 mg, contact time 14 min, and mixing speed 520 rpm. Under optimal conditions, limit of detection of 11.5, 14.6, and 19.1 μg/L and limit of quantification of 37.9, 48.3, and 63.0 μg/L were obtained for DMP, DEP and DEHP, respectively. The stability of phthalate esters adsorbed on ZnR@Si@Fe₃O₄ was very good (% recovery > 94% after 10 days stored at 25 °C). The applicability of the developed method was successfully validated by extraction and determination of selected analytes in urine samples, with extraction recoveries in the range of 92.1%–99.2%.