Ultra-trace Determination of Chromium (III) and Cobalt (II) Using Phosphonate Ester-Functionalized PAMAM Magnetite and DSPE-FAAS.

This study reports a simple and efficient dispersive solid-phase extraction (DSPE) method using phosphonate ester-functionalized poly(amidoamine) (PAMAM) dendrimer-coated magnetic nanoparticles for the trace determination of Co(II) and Cr(III) in environmental samples by flame atomic absorption spectrometry (FAAS). The nanoparticles were synthesized and characterized by NMR, FT-IR, SEM, and TGA analyses. Under optimized conditions, detection limits were 0.8 µg L⁻1 for Co and 1.9 µg L⁻1 for Cr, with linear calibration ranges of 2.5-250 µg L⁻1 and 5.0-500 µg L⁻1, respectively. Compared with direct FAAS, the enhancement factor (EF) was 110 for Co and 204 for Cr. Recovery tests in spiked tap water and black tea infusions yielded recoveries of 79% to 114%, confirming the method's precision and applicability in real matrices. This approach provides a cost-effective and reliable alternative to advanced instrumental methods and demonstrates the potential of functionalized magnetic sorbents for trace metal monitoring in environmental and food analysis.