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A magnetic sensor for detection of Pb~(2+) has been developed based on Fe/Fe_3O_4 nanoparticles modified by3-(3,4-dihydroxyphenyl)propionic acid(DHCA). The carboxyl groups of DHCA have a strong affinity to coordination behavior of Pb~(2+) thus inducing the transformation of Fe/Fe_3O_4 nanoparticles from a dispersed to an aggregated state with a corresponding decrease, then increase in transverse relaxation time(T_2) of the surrounding water protons. Upon addition of the different concentrations of Pb~(2+) to an aq. solution of DHCA functionalized Fe/Fe_3O_4 nanoparticles(DHCA-Fe/Fe_3O_4 NPs)([Fe] = 90 mmol/L), the change of T_2 values display a good linear relationship with the concentration of Pb~(2+) from 40 μmol/L to 100 μmol/L and from 130 μmol/L to 200 μmol/L, respectively. Owing to the especially strong interaction between DHCA and Pb~(2+), DHCA-Fe/Fe_3O_4 NPs exhibited a high selectivity over other metal ions.
A magnetic sensor for detection of Pb 2+ has been developed based on Fe / Fe 3 O 4 nanoparticles modified by 3- (3,4-dihydroxyphenyl) propionic acid (DHCA). The carboxyl groups of DHCA have a strong affinity to coordination behavior of Thus inducing the transformation of Fe / Fe_3O_4 nanoparticles from a dispersed to an aggregated state with a corresponding decrease, then increase in transverse relaxation time (T_2) of the surrounding water protons. Upon addition of the different concentrations of Pb Solution of DHCA functionalized Fe / Fe 3 O 4 nanoparticles (DHCA-Fe / Fe 3 O 4 NPs) ([Fe] = 90 mmol / L), the change of T 2 values shows a good linear relationship with the concentration of Pb 2+ from 40 μmol / L to 100 μmol / L and from 130 μmol / L to 200 μmol / L, respectively. Owing to the especially strong interaction between DHCA and Pb 2+, DHCA-Fe / Fe_3O_4 NPs exhibited a high selectivity over other metal ions.