Spinel CuMn₂O₄ nanoflakes as an effective adsorbent for dispersive solid phase microextraction of silver and lead in spices and water

In the current work, we synthesized spinel CuMn₂O₄ nanoflakes using coprecipitation and pyrolysis methods. The resultant adsorbent was used as a fast and selective adsorbent for D-SPμE of silver and lead ions in river water, tap water, well water, wastewater, red pepper, black pepper, cinnamon, and cumin. This is the first study on D-SPμE of silver and lead ions with nanoflake morphology among spinel oxides. Experimental factors affecting the extraction of the silver and lead ions by CuMn₂O₄ nanoflakes were examined. The optimal pH was found to be 2.0. Adsorption/elution contact times and eluent were no vortexing adsorption/30 s elution, and 2 mL of 2 mol L^-1 HCl, respectively. The adsorption capacity of the CuMn₂O₄ nanoflakes was 42.4 mg g^-1 for silver and 42.7 mg g^-1 for lead. The RSD% of the analytes was ≤3.1%. The selectivity of Pb(II) was very high. The results were verified by BCR-482 Lichen, SPS-WW1 Batch 121 Wastewater, and NW-TMDA-54.6 Lake water analyses. The recovery tests in the spice and water samples were done. The recovery ranges were found to be 90-102% and 93-102% for silver and 88-98% and 89-97% for lead in water and food, respectively. This indicates an accurate, reliable, fast, and selective approach for FAAS determination of silver and lead in the samples.