Graphene Oxide/MXene Nanocomposite Cross-Linked by Urea as a Sorbent for Thin-Film Microextraction of Fipronil and Permethrin and Their Quantification via High-Performance Liquid Chromatography-Ultraviolet Detection

Herein, a nanocomposite containing graphene oxide/MXene was prepared and cross-linked with urea as a novel sorbent. The sorbent was coated on the surface of a cellulosic paper to prepare a thin film for the thin-film microextraction process. The developed method was applied for the extraction of fipronil and permethrin (as model analytes), followed by separation and quantification using high-performance liquid chromatography-ultraviolet detection. Under optimal condition, the linear dynamic range of the method varied from 0.20 to 100.00 µg L⁻¹, with a correlation coefficient (r²) higher than 0.9967. The limits of detection and limits of quantification were determined to be in the ranges of 0.05–0.06 µg L⁻¹ and 0.17–0.19 µg L⁻¹, respectively. The relative standard deviations (%RSDs) ranged from 2.7% to 5.7%. Additionally, the enrichment factors (EFs) of the studied analytes were 72.00 and 83.00. To evaluate the applicability of the method for real sample analysis, cucumber, tomato, watermelon, and pear were selected and analyzed. The obtained recovery results (90%–116%) confirmed that the method is suitable for accurate analysis.