Ultrasonic assisted dispersive-solid phase extraction for preconcentration of trace metals in wastewater samples

In this work, MgO-SnO-Zeolite composites material has been synthesized, characterized, and, used as a sorbent material in the determination of Cd, Cr, Mn, Ni, and Zn in water samples using the ultrasonic-assisted dispersive-solid phase extraction. The synthesized MgO-SnO-Zeolite composite was prepared by the co-precipitation method and the results show the crystallinity phase of the material that exhibits most of the zeolite structure. Scanning electron microscopy with energy-dispersive X-ray spectroscopy was conducted on the composite material. The structure of the scanning electron microscopy images shows the cubic material with the energy-dispersive X-ray spectroscopy peaks that confirms the presence of the elements that form part of MgO-SnO-Zeolite. Furthermore, they were no impurities observed on the prepared composite material. The central composite design was used to optimize the adsorption and desorption of the developed ultrasonic-assisted dispersive-solid phase extraction method. The optimum conditions were: pH 7.5, extraction time 17.5 min, adsorbent mass 75 mg, desorption time 5 min, eluate concentration 2 M nitric acid, and desorption volume 7 mL. Under optimum conditions, the limit of detection was found to be 0.13, 0.45, 0.21, 0.34, and 0.08 µgL-1 for Cd, Cr, Mn, Ni, and Zn, with a preconcentration factor of 4.3. The intra-day (n = 15) and inter-day (n = 5) precision expressed as relative standard deviations ranged from 0.4 to 1.3 and 1.34-2.4, respectively. The developed ultrasonic-assisted dispersive-solid phase extraction method was found to be applicable for the determination of Cd, Cr, Mn, Ni, and Zn in wastewater samples.