Chitosan/thiol functionalized metal-organic framework composite for the simultaneous determination of lead and cadmium ions in food samples

Abstract

In this work, a facile solid phase extraction (SPE) method was developed for the analysis of trace Pb²⁺ and Cd²⁺ by using chitosan/thiol modified metal-organic frameworks (CS/MOF-SH) composite as adsorbent followed by graphite furnace atomic absorption spectrometer (GF-AAS) detection. The potential influencing factors, such as solution pH, adsorbent dosage, and extraction time, were fully estimated. Under the optimized extraction conditions, the detection limits of Pb²⁺ and Cd²⁺ were 0.033 µg L^-1 and 0.008 µg L^-1, respectively. Compared to other studies, CS/MOF-SH not only possessed superior adsorption performance, but also had the advantages of ease of handling and recyclability. Encouragingly, the developed method was of high accuracy and could monitor trace Pb²⁺ and Cd²⁺ in various certified reference materials (rice, wheat and tea) with complicated matrices, demonstrating its practical potential for regular monitoring of trace heavy metal ions in real food samples.

Keywords: Chitosan; Graphite furnace atomic absorption spectrometer; Metal organic frameworks; Solid phase extraction; Trace metal ions determination.