| Diethylstilbestrol (DES) was a hormone medicine and often applied in production of animals. Since it could stimulate the growth of animals and adjust physiological function role. Therefore it was often illegally abused as additives. In order to study the residue of DES in animal foods, this paper mainly studied the electrochemical behavior of Diethylstilbestrol in the composite film electrode.The glassy carbon electrode was modified by methylene blue and multi-walled carbon nanotubes (PMB-MWNT), and tested the chemical components and electrical activity by infrared spectrometry and electric analysis method .The result showed that theπ-πcombined on the lateral wall of MWNT, which improved the modified electrode surface. Determination of the standard substance was by cyclic voltammetry. Near to 0.197V, there was a redox peak in the pH7.0 of PBS buffer (scanning speed: 200mV/s; accumulate time: 80s) .The oxidation peak current was linear with the concentration of DES over the range from 3.73×10-11 mol/L to 3.73×10-8 mol/L. The detection limit was 6.8×10-3ug/kg.In addition, a new method was established about determination of the possible exogenous female hormones in milk. In the determination conditions of optimizing square-wave voltammetry (square amplitude,25mV; frequency ,10Hz; potentiometer incremental,11mV; sedimentary, 80s) , found that the oxidation peak current was linear with the concentration of DES by the internal standard method, the linear regression equation was Ip(uA) =9.045+4.0 C(μg/L). The detection limit was 0.0634ug/kg. It also examined the influence of the coexistence of ions(Mg2+,Zn2+,Ca2+ ,K+, Cu2+, Fe2+,Fe3+)and the results showed that there were no interference phenomenon.To sum up, the determination of exogenous estrogen could based on Multi-walled carbon nanotubes immobilization of methylene blue (MWNT/PMB/ GCE) modified glassy carbon electrode, and this method was convenient, sensitive, time saving, etc.
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