MSIS-МP-АЕS determination of As and Sb in complex matrices by magnetic nanoparticles-assisted hydride generation

The advantages of the microwave plasma atomic emission spectrometry (MP-AES) for hydride generation (HG) by means of modified Multi Mode Sample Introduction System (MSIS®) have been revealed for analysis of As and Sb in complex real samples. Two main outcomes have been achieved: (i) reliable analysis and higher tolerability to less diluted matrices and (ii) a multifold reduction in the methodological limits of detection (MLOD). For the first time in real samples analysis the HG is assisted by silica-coated magnetic nanoparticles (MNPs) (∼2 mg mL^-1 MnFe₂O₄@SiO₂) added to the hydrogenation reagent stream (1.5% NaBH₄). This innovative approach provides smooth hydrides generation from problematic matrices, better gas-liquid separation and steady gas transport from the MSIS chamber. The effect is due to the elimination of NaBH₄ delivery interruptions, the foam suppression in the reactor and levelling the carbon amount carried to the MP. The used inert MNPs could be collected from the drain with a permanent magnet and appear to be recyclable and reusable without memory effect or efficiency loss. The achieved benefits are demonstrated in the determination of As and Sb in three types of complex matrices: industrial electrolyte with high dissolved solids content, human urine prone to intensive foam creation, and sparkling mineral water releasing CO₂.