Magnetic Luffa@metal-organic frameworks (MOF-199) nanocomposite for the solid phase microextraction of some metal ions at trace levels from food and water samples

A new adsorbent (magnetic Luffa@MOF-199) was synthesized and used for magnetic solid phase microextraction for separation-preconcentration of Ni(II), Pb(II), Cr(III), and Cd(II) as 2-nitroso-2-naphthol chelates prior to their flame atomic absorption spectrometer (FAAS) detection. Analytical parameters that affect the quantitative recoveries of analytes such as pH, adsorbent amount, sample and eluent volumes, adsorption and desorption time, and eluent type were optimized. The impact of foreign ions was investigated. The limits of quantification (LOQ) values were 0.35 mu g L-1 for Ni(II), 0.38 mu g L-1 for Pb(II), 0.55 mu g L-1-for Cr(III) and 0.12 mu g L-1 for Cd(II). The relative standard deviations (RSD) were in the range of 3.4 - 6.0%. The developed method was validated using certified reference materials (CRMs) (TMDA-64.3 fortified water, GBW07424 (GSS-10) soil and 1573a Tomato Leaves). The method was applied-for determination of Ni(II), Pb(II), Cr(III), and Cd(II) contents of some food, tobacco, and wastewater samples.