Soheila Arghavani - Department of Chemistry, Faculty of Sciences, University of Birjand, Birjand, ۹۷۱۷۹-۴۱۴, Iran.
Rouhollah Khani - Department of Chemistry, Faculty of Sciences, University of Birjand, Birjand, ۹۷۱۷۹-۴۱۴, Iran.

A reliable and sensitive method was developed for the determination of thymol by magnetic dispersive micro-solid phase extraction (MD-µSPE) based on the use of Escherichia coli bacteria. It was immobilized on the γ-Fe۲O۳ magnetic nanoparticles and used as a bio-sorbent for MD-µSPE. The properties of the synthesized bio-sorbent were characterized by Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray (EDX), and field emission scanning electron microscopy (FE-SEM). Central composite design (CCD) combined with desirability function approach was applied to search for optimal operational conditions. Under the optimum conditions specified as: ۲۵ min ultrasonic time, pH=۵, ۳۰ mg of bio-adsorbent, and temperature ۳۵ °C, high and reasonable linear range over ۳۰ - ۵۰۰ ng mL-۱ (R۲ > ۰.۹۹۶۵) with limit of detection (LOD) ۹.۱۸۳ ng mL−۱ were obtained. Finally, the proposed method was successfully used for extraction and determination of thymol in food and cosmetic samples

Thymol, Biosorption, Escherichia coli, Central composite design, Food and cosmetic samples.