Replaceable polydopamine doped toxic elements extraction sponge integrated magnetically actuated microfluidic sample preparation device

Sample preparation is a critical step in inductively coupled plasma mass spectrometry (ICP-MS) because it ensures that analytes are introduced into the instrument in an appropriate matrix. Integrating microfluidic technology into sample preparation improves analytical sensitivity and selectivity while reducing reagent consumption and manual handling. However, efficient mixing remains challenging in microfluidic systems because laminar flow limits mass transfer and reduces trace-element separation efficiency. To address this limitation, a magnetically actuated microfluidic device with a miniaturized magnetic stirrer was designed for sample preparation before ICP-MS analysis. The proposed device incorporates a replaceable polydopamine/chitosan/Fe₃O₄ sponge (PDA/CS/Fe₃O₄ sponge) as the solid-phase extraction sorbent. A microinjection pump integrates sample loading, separation, washing, and elution. This automated workflow reduces manual operation and improves analytical efficiency. Moreover, magnetic actuation enhances mass transfer and improves separation efficiency. The proposed device exhibited linear calibration curves over 1-100 μg L^-1, with coefficients of determination (R²) of 0.9916, 0.9944, and 0.9978 for Cr, As, and Pb, respectively. Recoveries obtained from spiked tap, river, and lake water samples ranged from 80 to 119%. Overall, the proposed platform provides a sustainable and efficient approach for microfluidic-based sample preparation and demonstrates considerable potential for toxic elemental analysis using ICP-MS.