Solid-phase extraction using molecularly imprinted polymer for selective extraction of natural and synthetic estrogens from aqueous samples

A method is proposed for the clean-up and preconcentration of natural and synthetic estrogens from aqueous samples employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE). The selectivity of the MIP was checked toward several selected natural and synthetic estrogens such as estrone (E1), 17 beta-estradiol (beta-E2), 17 alpha-estradiol (alpha-E2), estriol (E3), 17 alpha-ethinylestradiol (EE2), dienestrol (DIES) and diethylstilbestrol (DES). Ultrahigh pressure liquid chromatography (UHPLC) coupled to a TSQ triple quadrupole mass spectrometry (QqQ) was used for analysis of target analytes. The chromatographic separation of the selected compounds was performed in less than 2 min under isocratic conditions. The method was applied to the analysis of estrogens in spiked river and tap water samples. High recoveries (>82%) for estrone, 17 beta-estradiol, 17 alpha-estradiol, estriol and 17 alpha-ethinylestradiol were obtained. Lower but still satisfactory recoveries (>48%) were achieved for dienestrol and diethylstilbestrol. The method was validated and found to be linear in the range 50-500 ng L-1 with correlation coefficients (R-2) greater than 0.995 and repeatability relative standard deviation (RSD) below 8% in all cases. For analysis of 100-mL sample, the method detection limits (LOD) ranged from 4.5 to 9.8 ng L-1 and the limit of quantitation (LOQ) from 14.9 to 32.6 ng L-1. To demonstrate the potential of the MIP obtained, a comparison with commercially available C-18 SPE was performed. Molecularly imprinted SPE showed higher recoveries than commercially available C-18 SPE for most of the compounds. These results showed the suitability of the MIP-SPE method for the selective extraction of a class of structurally related compounds such as natural and synthetic estrogens. (C) 2011 Elsevier B.V. All rights reserved.