Electro-deposited poly-luminol molecularly imprinted polymer coating on carboxyl graphene for stir bar sorptive extraction of estrogens in milk

Electrochemical polymerization of luminol molecularly imprinted polymer on carboxyl graphene (MIP/CG) was developed as stir bar sorptive extraction (SBSE) coating for selective pre-concentration and specific recognition of bisphenol A (BPA), hexoestrol and diethylstilbestrol in milk samples. Luminol was employed as monomer and BPA as the template to prepare MIP under 0-0.6 V electro-polymerization. Carboxyl graphene was modified on pencil lead as the substrate to increase extraction capacity. The preparation and extraction conditions affecting the extraction efficiency were optimized. Under the optimized conditions, a good linearity of three estrogens was obtained in the range of 4-1000 ng mL(-1). The average recoveries at the three spiked levels of the three estrogens ranged from 83.4% to 96.3% with the relative standard deviations (RSD) <= 7.1%. The limits of detection were in the range of 0.36-1.09 ng mL(-1). The developed method with low cost, high selectivity and good reproducibility can be potentially applied for determining trace estrogens in complex food samples. (C) 2016 Elsevier B.V. All rights reserved.