Enhanced in-out-tube solid-phase microextraction by molecularly imprinted polymers-coated capillary followed by HPLC for Endocrine Disrupting Chemicals analysis.

A novel Estrone (E1) molecularly imprinted polymers (MIPs-E1)-coated solid-phase microextraction (SPME) fiber was prepared by in-situ polymerization on inner and outer surface of the capillary, namely MIPs-E1-coated in-out-tube SPME (MIPs-E1-IOT-SPME), which combines the advantages of enhanced extraction efficiencies of IOT-SPME and specific adsorption abilities of MIPs, and shows nearly double enrichment capacity compared to in-tube SPME (IT-SPME). The extraction conditions were optimized and a method for determination six endocrine disrupting compounds (EDCs) by MIPs-E1-IOT-SPME coupled with HPLC is developed. The MIPs-E1 coating was characterized by fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), N2 adsorption-desorption and Thermal gravimetric analysis (TGA). Under the optimum condition, the MIPs-IOT-SPME-HPLC method shows low limits of detection (LODs) (0.21-0.80 μg L-1) and limits of quantification detection (LOQs) (0.69-2.6 μg L-1), wide linear ranges from 10.0 to 1000 μg L-1 for each compound with exception of E2 and E3 from 20.0 to 1000 μg L-1, and acceptable reproducibility of one fiber for five parallel determinations is 2.4-6.6% (RSD) and fiber-to-fiber is 4.5-8.1% (RSD). The satisfactory recoveries are in the range of 88.5-105.1% with good RSDs less than 7.9% at the five spiked levels of 20.0, 50.0, 80.0, 200.0 and 500.0 μg L-1. Moreover, when compared with commercial fibers, the MIPs-E1-IOT-SPME fiber displays excellent adsorption capacity and specific selectivity.