Аңдатпа
An efficient, simple, rapid, low-cost, and environmentally friendly method based on ultrasound assisted dispersive micro solid phase extraction (UA-D-µ-SPE) using a nickel oxide/kaolin magnetized nanocomposite was developed for extraction and determination of trace rare heavy metals including lanthanum, cerium, and samarium from complex environmental samples. Characterization results confirmed that the nanocomposite possesses a very high specific surface area, good chemical and thermal stability, recyclability, and splendid performance. One of the most significant advantages of this method is the elimination of the centrifugation step, which enhances simplicity, reduces operation time, and improves efficiency compared with conventional and complicated microextraction methods. Moreover, the synergy between the layered structure and mechanical stability of kaolin with the catalytic property and high surface area of NiO under ultrasonic irradiation led to uniform dispersion, reduced adsorption equilibrium time, and enhanced extraction efficiency even in complex matrices. The optimal conditions were systematically evaluated and optimized by recruiting a central composite design (CCD). The type of eluent solvent was optimized in a single-variable manner. The optimized parameters obtained were: pH 4.0, 25 mg adsorbent, 188 s adsorption time, 5 M HCl eluent concentration, 1.4 mL eluent volume, and 120 s desorption time. The developed method achieved limits of detection (LOD) of 1.0, 1.0, and 0.8 ng mL -1 and limits of quantification (LOQ) of 3.4, 3.4, and 2.7 ng mL -1 for lanthanum, cerium, and samarium, respectively. The intra-day relative standard deviations (RSDs) were 4.8%, 4.4%, and 4.4%, while the inter-day RSDs were 6.1%, 5.8%, and 5.3%, respectively. The proposed method was adopted for analysis of environmental samples in presence of complex and interfering matrices, achieving recovery rates in the range of 93.7–100.4%. In conclusion, the synthesized magnetic nanocomposite was successfully employed as an adsorbent in ultrasound-assisted dispersive micro solid-phase extraction method for extraction and preconcentration of mentioned metals from environmental samples.