1.
A novel electrochemical sensor based on Fe3O4-doped nanoporous carbon for simultaneous determination of diethylstilbestrol and 17β-estradiol in toner.
Chen, X, Shi, Z, Hu, Y, Xiao, X, Li, G
Talanta. 2018;:81-90
Abstract
In this paper, Fe3O4-doped nanoporous carbon (Fe3O4-NC) was synthesized through the carbonization of Fe-porous coordination polymer (Fe-PCP), which are also known as metal-organic framework (MOF), and fabricated into an electrochemical sensor for simultaneous analysis of diethylstilbestrol (DES) and 17β-estradiol (E2) in toner. Fe3O4-NC was characterized by scanning electron microscope (SEM), powder X-ray diffraction (pXRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, N2 adsorption-desorption and so on. It is of great practical significance to achieve the simultaneous determination of the two estrogens because estrogens are co-existing in many real samples. The simultaneous determination of two common estrogens, DES and E2, was achieved through electro-catalytically oxidization at a Fe3O4-NC modified glassy carbon electrode (Fe3O4-NC/GCE). The peak currents of DES and E2 increased linearly as their concentrations increasing from 0.01 to 12 μmol/L and from 0.01 to 20 μmol/L, with detection limits of 4.6 nmol/L and 4.9 nmol/L (S/N = 3), respectively. This work was focused on the simultaneous determination of the two estrogens in toner. Furthermore, the recoveries of DES and E2 were 91.2-110%, in actual toner samples. The experimental results manifest that the sensor with a stronger anti-interference ability can be used for the simultaneous detection of DES and E2 in the actual toner sample.
2.
Kinetics and mechanism of 17β-estradiol chlorination in a pilot-scale water distribution systems.
Li, C, Dong, F, Crittenden, JC, Luo, F, Chen, X, Zhao, T
Chemosphere. 2017;:73-79
Abstract
The kinetics and mechanisms of 17β-estradiol (E2) chlorination in water distribution systems (WDS) were studied. We examined the impacts of different factors, including pH, temperature, humic acid concentration and type, and flow velocity. The experimental results showed that the rate constants in beaker tests and WDS were described by a pseudo-first-order model. pH had the greatest impact on E2 chlorination in the beaker tests. However, temperature had the greatest impact on E2 chlorination in WDS. Mechanistic analysis of E2 chlorination showed that chlorine attacked E2 in three stages: 1) halogenation of the aromatic ring, 2) cleavage of the benzene moiety and chlorine or bromine substitution formation, and 3) formation of trihalomethanes (THMs) and halogenated acetic acids (HAAs) from phenolic intermediates through benzene ring opening with chlorine and/or bromine substitution of hydrogen on the carbon atoms. In the third stage, the concentrations of THMs and HAAs increased rapidly.