Lead analysis by μSPE/FF-AAS: A comparative study based on dimethylglyoxime functionalized silica-coated magnetic iron/graphene oxides

Here, four new sorbents based on dimethylglyoxime (DMG) functionalized silica-coated magnetic iron/graphene oxides (Fe₃O₄/MGO) were synthesized. A comparative study was performed among them to evaluate the different substrates and the role of the spacer in improving the lead extraction efficiency and selecting the most efficient sorbent. Based on experimental results, MGO@SiO₂@3-chloropropyltrimethoxysilane@DMG was selected for magnetic dispersive μSPE of lead followed by flame (FAAS) and graphite furnace atomic absorption spectroscopy (GFAAS). The sorbents were characterized by FT-IR, FE-SEM, EDX, TEM, and Zeta potential. Sorbent amount (40.5 mg), sample pH (7.7), sonication time of adsorption and desorption procedures (9 min), and volume and acid concentration (2.2 mL of 2.7 mol L^-1 nitric acid) were optimized using experimental design. Linearity of 20.0-600.0 ng mL^-1 and 0.5-3.0 ng mL^-1 resulted by FAAS and GFAAS, respectively. LODs were 7.0 and 0.2 ng mL^-1 by FAAS and GFAAS, respectively. Intra- and inter-day RSDs% (n = 3) at two concentration levels of 3.0 and 100.0 ng mL^-1 were below 7.6%.The adsorption capacity was 45.05 mg g^-1. The adsorption isotherm showed a better fitting with the Langmuir model. Relative recoveries (%) of 87.8-115.1% were obtained for measuring trace amounts of lead in water, hair, and nail samples.