The procedure used for functionalized magnetic solid-phase extraction (MSPE). With kind permission from Springer Science + Business Media, ref. 29, Analytical and Bioanalytical Chemistry, Application of functionalized magnetic nanoparticles in sample preparation, 406, 2, 2013, 377–399, Xie L., Jiang R., Zhu F., Liu H. and Ouyang G., © Springer-Verlag Berlin Heidelberg 2013.