Lead is a very stable and non-biodegrade that accumulates in the environment [1]. It is considered as one of the toxic heavy metals, which can cause damage to the human health, even at the low concentrations. Numerous techniques have been used for the determination of lead such as electrochemical method [2], electrothermal atomic absorption spectrometry (ETAAS) [3], inductively coupled plasma-atomic emission spectroscopy (ICP-AES) [4] and flame atomic absorption spectroscopy (FAAS) [5]. However, their selectivity and sensitivity are not sufficient for direct determination of lead in real samples at very low concentrations. In this study, a magnetic metal-organic frameworks (MOFs) is synthesized based on magnetic Fe3O4 and 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 magnetic MOFs and easily separated by a magnet; so, no filtration or centrifugation was necessary. The analyte ions were eluted using HCl 0.5 M and analyzed via graphite furnace atomic absorption spectroscopy. Under optimal experimental conditions, the method has a linear range of 0.1–50 ppb and detection limit (LOD) of 0.08 ppb. The results showed that the prepared sorbent has high selectivity for Pb2+ even in the presence of other interfering metal ions.
