Ultra-sensitive determination of carcinogenic aflatoxins in food matrices using a novel magnetic bimetallic ZIF-8@chitosan sorbent and dispersive micro-solid phase extraction

Abstract

A dispersive micro-solid phase extraction (D-µ-SPE) method coupled with HPLC-FLD was developed for the sensitive determination of carcinogenic aflatoxins. A novel magnetic composite sorbent was synthesized by integrating bimetallic Co/Zn ZIF-8, chitosan, and Fe₃O₄ nanoparticles. Statistical comparison revealed that bimetallic Co/Zn ZIF-8 exhibited significantly enhanced aflatoxin extraction efficiency over its monometallic counterpart, with subsequent functionalization using chitosan and magnetization further improving performance. Key extraction parameters were systematically optimized using experimental design. The validated method demonstrated wide linearity (0.02–120 ng mL⁻¹; R² > 0.993), and low detection limits (LODs: 0.006–0.07 ng mL⁻¹), and quantification limits (LOQs: 0.02–0.21 ng mL⁻¹). Precision ranged from 3.7–4.7% (intra-day) to 4.5–6.2% (inter-day). Given the critical need to monitor these potent toxins in high-consumption and high-risk commodities, the method was successfully applied to commercial mineral water (potential environmental contamination), rice (global dietary staple), and peanut (notoriously susceptible crop) samples. Relative recoveries of 91.2–98.0% (RSD < 4.4%) confirmed the method's robustness and accuracy for complex matrices.