Synthesis of N-doped carbon nano-onion-zirconium-based metal–organic framework composite and its application in dispersive micro-solid-phase extraction of patulin from apple juice followed by HPLC analysis

One of the most prevalent hazardous mycotoxins in foods is patulin, which shows a serious hazard for consumers. Therefore, it is crucial to develop an efficient technique to determine patulin in foods. In the current work, a dispersive micro-solid-phase extraction procedure was developed for the extraction of patulin from apple juice samples prior to its determination by high-performance liquid chromatography coupled with a photodiode array detector. For this purpose, N-doped carbon nano-onion and metal–organic framework composite was successfully synthesized and characterized. Then, the extraction procedure was done by dispersion of the nanocomposite into the sample solution containing the analyte by sonication. After centrifuging of the mixture, the analyte was eluted from the surface of the sorbent and used in the determination step. Several significant parameters affecting the performance of the proposed method such as the sorbent amount, ionic strength, adsorption and desorption times, elution solvent type and volume, and pH were evaluated and optimized by "one-parameter-at-a-time" approach. The offered method revealed low limits of detection (1.62 ng mL⁻¹) and quantification (5.39 ng mL⁻¹), and a broad linear range (5.39–250 ng mL⁻¹). Acceptable enrichment factor (113) and extraction recovery (56.6%) were obtained for the method. The method’s usefulness was confirmed by the analysis of different packed apple juice and fresh apple juice samples.