Preconcentration and Determination of Copper(II) in Water and Tea Infusion Samples Using Hierarchical MnSb₂O₆@Fe₃O₄ Nanoparticles and Magnetic Solid Phase Extraction–FAAS

Heavy metal pollution poses a significant threat to living organisms and requires continuous monitoring of the environmental samples. In this study, novel hierarchical MnSb₂O₆@Fe₃O₄ nanoparticles were synthesized and used as adsorbents in magnetic solid-phase extraction (MSPE) of Cu(II). The strong magnetic properties of these nanoparticles enabled rapid and efficient separation from complex matrices, simplifying preconcentration and ensuring high adsorption efficiency. By integration of MSPE with flame atomic absorption spectrometry (FAAS), matrix effects were reduced, detection limits improved, and the cost-effectiveness and simplicity of FAAS were leveraged for Cu(II) analysis in complex samples. The optimized parameters for the MSPE-FAAS method included pH, stirring time and type, eluent volume and type, and adsorbent amount, achieving a correlation coefficient of 0.9991, a limit of detection of 2.1 ng·mL^-1 and a linear range of 10.0-200 ng·mL^-1. The developed method enhanced FAAS sensitivity by 48-fold and was successfully applied to wastewater, tap water, and apple tea samples, achieving recoveries of 93-102%. The Cu(II) adsorption capacity of MnSb₂O₆@Fe₃O₄ was determined to be 15.2 mg·g^-1, demonstrating its high efficiency for heavy metal removal. This methodology highlights a robust and efficient approach for preconcentrating trace metals from diverse and complex matrices, combining the advantages of MSPE and FAAS in a practical, cost-effective system.