The Research On Determination Of Environmental Estrogens

Environmental Estrogens, a kind of endocrine disrupters, have been shown to induce abnormal differentiation and development of reproductive organs by mimicking or interfering with the action of endogenous gonadal steroid hormones. Unfortunately complex sample matrices in biological and environmental samples often affect the accuracy of DBP determination. The traditional determination methods for this kind of pollutants need tedious and time- consuming pretreatment procedures for its trace concentration in environment. Solid phase extraction (SPE) has become a routine sample pretreatment method. It has many attractive features, such as ease operation, high load abilities, higher recoveries, lower consumption of organic solvent, and automation capabilities and so forth. However, traditional SPE is usually based on non- selective interactions between the analyte molecule and the sorbent, which often leads to coextraction of many matrix components. Recently , solid phase microextraction(SPME) has been used as an attracting method because of it's high efficiency. But the frangible fibre not only increased the cost of experiment but also restricted the application of SPME.To achieve better extraction efficiency, molecularly polymers (MIPs) were take into considerision. MIPs are synthetic cross- linked polymers formed by the presence of a target molecule (template). The template is then removed, which produces a cavity with molecular recognition sites that can bind selectivity to the original template. The feature of MIPs is just like the extraction sorbents involving reversible and selective antigen- antibody interactions. They give extracts which are almost free of interfering substances. MIPs have advantages such as physical robustness, high strength, resistance to elevated temperatures and pressures, and inertness towards organic solvents, acids or bases. The application of MIPs has become the most promising development of selective detection method for trace analysis.In this research, DBP was chosen as model molecular of environmental estrogens to examine the possibility of using MIPs to work with quartz crystal microbalance(QCM) as a novel biosensor. After optimizing the preparing conditions, The DBP MIP-QCM was used to determine low concentration of DBP in environmental water directly, without pretreatment with the sample. Also, a new method of liquid phase microextration using only little amount of solvent (such as xμl) was developed in this paper to concentrate DBP in water.1. In this paper, Nine kinds of DBP imprinted polymers were synthesized by sol-gel polymerization. Effects of the preparing conditions and imprinted effect of the polymers were investigated. Results showed:(1) Polymers synthesized by different functional monomer show very different character. MIP4 and MIP5 solidified within few minutes, it's too fast to be coated on the sensor as sensitive membrane. MIP3 and MIP6 were hard to remove the template by several kind of eluents compared with MIP1,MIP2,MIP4,MIP5 . Compared with non- imprinted polymer,only MIP prepared by PTMOS functional monomer show great difference in adsorb template, indicating the prominent effect of imprinting.(2) In the procedure of polymerization, ethanol was not only used as solvent but also as the product of reaction. So it affected the reaction balance and then the yield. From the adsorption curve, polymer prepared with more enthanol show poorer adsorption ability. So we choose ethanol-TEOS ( 3:1, mol/mol).(3) Dichloromethane and methanol showed similar good eluting effect. Because of the high volatility and strong toxicity of dichloromethane and trichloromethane, we choose methanol as eluent of MIP1.(4) MIP1 showed good selectivity and sensitivity to DBP. MIP1 was used as membrane of MIP-QCM to adsorb DOP and BBP which have similar structures to DBP. With the improving of concentration, MIP-QCM showed little change in adsorption amount, which indicated the good selectivity of MIP1.2. DBP imprinted MIPs were coated to the gold electrode of quartz crystal microbalance (QCM) as the sensitive membrane of novel biosensor. Environmental water samples were detected directly. MIP-QCM show good stability and repeatibility. Standard deviation of frequency shifts for 10 times detection of 1ppm DBP were3.86%. The calibration graph of DBP standard solution was linear under 20ppm with correlation coefficient 0.9917, slope 112.02Hz/ppm. The selectivity to DBP, DOP and BBP was evaluated, MIP-QCM showed best selectivity to DBP, which coincided with our anticipation to the experiment.3. A liquid phase micro-extraction procedure using toluene was demonstrated for the sensitive determination of DBP in water samples. The optimum conditions were: 2μl toluene as extraction solvent, stirring speed :300r/min, extraction time : 20min, distance from immersed solvent drop to surface of solution: 1cm. When combined with gas chromatography, the calibration graph of DBP was linear in the concetration ranges of 0.5 to 50μg/L with less than 11.75% RSD and the revoveries were 89.3%-104.5%. The enrichment factor for DBP was 191 as 10 ml water sample were analysed. For spiked lake water samples the recoveries were 94.5%-107.8%.Results from this research provided two kinds of new methods for the detection of DBP. Liquid phase micro-extraction procedure conbined the advantages of LLE and SPME, sampling, extracting and concentrating was finished in one step. It's a fast, cheap pretreatment technique friendly to enviroment, with high sensitivity, simple procedure, and little organic solvent which show special merit to the trace detection of DBP in environmental samples.MIP-QCM for direct DBP detection in was assembled for the first time. Because of the small cubage , high stability and simple operation, it's hopeful to be ameliorated to a kind of portable detector for DBP in eviromental samples.