On-line Concentration Coupling To High-performance Liquid Chromatography For Determination Of Estrogens In Water

As a kind of endocrine disruptor substances, estrogens have been proven to be initiators in the carcinogenic process, and they may result in a decrease in human sperm count and quality, also male reproductive dysfunction. They may even disrupt the whole ecosystem. There are lots of detection methods of estrogens, but a method that has very low detection limit is needed to detect trace estrogens in water. So it is necessary to select appropriate pre-treatment to concentrate the water samples and achieve a low limit of detection.Using cigarette filters and estrone-molecular imprinted polymer as solid-phase extraction (SPE) sorbent, the method described in this article was developed basing on on-line coupling of SPE to high-performance liquid chromatography (HPLC) for the determination of trace estrogens in water samples. This method achieved a very low limit of detection by pre-concentration to satisfy the requirement of detection of trace estrogens in water. The method packed SPE sorbents in a stainless steel cartridge, and use it instead of the loop on the six port injector valve, coupled to on-line flow inject analyzer to continuously perform extraction of estrone, estradiol, estriol and diethylstilbestrol from aqueous samples without any other pre-treatment. Using methanol and water for chromatographic separation, and the pH of samples, sample loading flow rate and desorption time were all optimized, and the performances of the sorbents were satisfactory. The method is fast, precise, costless and easy to operate.Cigarette filters used in this experiment have a same enrichment effect as classical SPE material C18, and the results shown that it can be developed as a potential sorbent of SPE. The detection limits for pre-concentrating 50mL of standard solution using cigarette filter as sorbent ranged from 0.98 to 78.1 ng L^-1. The enhancement factors were in the range of 197-326. The recoveries of estrogens spiked in real water samples ranged from 85 to 112 %. The precisions for nine replicate measurements of a standard mixture were in the range of 1.0-3.4%. Considering that ordinary sorbent usually have worse selectivity, we used sol-gel surface molecular imprinting technique to synthesized a molecular imprinting polymer (MIP) using estrone as template, and applied it for detection of estrone in water. MIP had a specific adsorption to estrone comparing to non-imprinted polymer, and its enrichment multiples of estrone can reach 1045 times, the limit of detection was 5.7 ng L^-1.