The increasing demand for natural antioxidants such as thymol in food and pharmaceutical industries highlights the need for sensitive and eco-friendly analytical methods capable of detecting this compound at trace levels. In this study, an environmentally benign magnetic biopolymer nanocomposite, Fe 3 O 4 @Pectin/Chitosan, was synthesized through a simple co-precipitation route and fully characterized using Fourier transform infrared, X-ray diffraction, transmittance electron microscopy, field emission scanning electron microscopy, electron diffraction X-ray, thermal gravimetric analysis, and vibrating sample analysis. The nanocomposite was employed as an efficient adsorbent in a magnetic dispersive micro-solid phase extraction (MDµ-SPE) system for the preconcentration of thymol. A central composite design combined with response surface methodology was used to optimize key operational parameters, resulting in optimal conditions of pH 7, 30 mg sorbent, 30 min adsorption time, and 40 °C. Under these conditions, the method achieved an extraction recovery above 95%, a linear dynamic range of 25–700 ng·mL −1 , and low detection and quantification limits of 7.5 and 24.75 ng·mL −1 , respectively. The sorbent exhibited excellent reusability for at least seven cycles without significant loss in performance. The method was successfully applied to thyme and honey samples, confirming its accuracy and selectivity in complex matrices. These findings demonstrate that the Fe 3 O 4 @Pectin/Chitosan–based MDµ-SPE platform provides a rapid, sensitive, and sustainable strategy for trace analysis of thymol in real food products.
Senobari et al. (Mon,) studied this question.