Preparation of multi-walled carbon nanotubes functionalized magnetic particles by sol–gel technology and its application in extraction of estrogens

Magnetic silica particles coated with hydroxy-terminated multi-walled carbon nanotubes (MWCNTs–OH) were prepared by sol–gel technology, characterized and used for the convenient, rapid and efficient extraction of several estrogens (including diethylstilbestrol, estrone and estriol) in water followed by sweeping micellar electrokinetic chromatography analysis with UV detection. The results demonstrated that sol–gel technology was a feasible, simple and effective technique for the preparation of MWCNTs–OH functionalized magnetic silica particles. The factors affecting the extraction efficiency of estrogens (the pre-activation of magnetic particles, adsorption time, desorption time and the amount of elution solvent) were carefully investigated. The extraction efficiencies for diethylstilbestrol, estrone and estriol were 95.9%, 93.9%, and 52.4%, respectively, under the optimum conditions. The method detection limits for the three estrogens were less than 0.2 ng mL−1. The developed method was applied for the analysis of tap water, mineral water, Pearl River water and honey.