Preconcentration of Pb(II) by Magnetic Metal-Organic Frameworks and Analysis Using Graphite Furnace Atomic Absorption Spectroscopy.

In this study, a magnetic metal-organic framework (MOF) was synthesized based on magnetic Fe 3 O 4 , Cu(II), and benzene-1,3,5-tricarboxylic acid (Cu-BTC) as a sorbent for solid phase extraction (SPE) of trace amounts of Pb(II) in water and lettuce samples. Pb(II) ion was adsorbed on the magnetic MOF and easily separated by a magnet; therefore, no filtration or centrifugation was necessary. The analyte ions were eluted by HCl 0.5 mol·L -1 and analyzed via graphite furnace atomic absorption spectroscopy. The prepared sorbent was characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and Fourier transform-infrared (FT-IR) spectroscopy. Under optimal experimental conditions, the method had a linear range of 0.1-50  μ g·L -1 . The limits of detection and quantitation for lead were found to be 0.026 and 0.08  μ g·L -1 , respectively. The results showed that the prepared sorbent has high selectivity for Pb 2+ even in the presence of other interfering metal ions.