Ultrafast Micro solid-phase extraction of cobalt using a novel magnetic europium-metal organic framework nanocomposite from fruits, vegetables, and different water samples.

Abstract

Trace cobalt contamination in food and water poses environmental and health concerns. This paper presents a novel magnetic europium-metal organic framework (Eu-MOF) nanocomposite for rapid magnetic micro-solid-phase extraction of Co(II) prior to flame atomic absorption spectrometric analysis. The adsorbent was synthesized hydrothermally as a Eu-MOF and functionalized with Fe₃O₄ nanoparticles. Ten milligrams of magnetic Eu-MOF effectively extracted Co(II) from a 45 mL sample at pH 8 within 15 s of hand shaking. The method achieved a limit of detection of 2.21 μg L-1 and a preconcentration factor of 22.5. Coexisting ions showed negligible interference, confirming high selectivity. The adsorbent was reusable for nine cycles without performance loss. The method was successfully applied to various food samples, natural waters, and wastewaters, yielding spike recoveries of 81-104%. The proposed approach offers a sensitive, rapid, and efficient magnetic μ-SPE strategy for trace cobalt determination in complex matrices.