Application Of Novel Dispersive Liquid-liquid Microextraction In The Determination Of Environmental Estrogens In Water

As a class of endocrine disruptors,environmental estrogens possess the ability to simulate or interfere with the body's endocrine function.They can be enriched in the body through the food chain,or by environmental exposure(water)and biological contact,thereby affecting the organisms of various systems,damaging the stability of the body environment,endangering the health of the organism.Therefore,it is very important to monitor environmental estrogens in various water samples.In this paper,two new pretreatment methods were developed for the determination of environmental estrogens in water samples.The thesis is divided into three chapters,the main contents are as follows:Chapter 1:A brief overview of sample pretreatment methods is presented.In this paper,the methods of dispersive liquid-liquid microextraction and extraction of environmental estrogens were introduced,as well as the background and research contents of this paper.Chapter 2: A counter current salting-out homogeneous liquid-liquid extraction and dispersive liquid-liquid microextraction method was established for the simultaneous determination of environmental estrogens in water samples by HPLC-UV.In this experiment,the effects of the sort and volume of extraction solvent,flow rate,pH and ionic strength on the extraction efficiency were investigated.The optimum extraction conditions were as follows: 2 mL acetonitrile;flow rate 0.4 m L / min;50 ?L carbon tetrachloride;10% ionic strength.Good linearites were obtained for diethylstilbestrol and octylphenol(R2 > 0.9991),and LODs were between 0.09 and 0.20 ng / mL.The recoveries were in the range of 81.4-105.9 % and the relative standard deviations were between 1.0 and 7.6 %.The proposed method has been successfully applied to the detection of river water,well water,bottled water and campus drinking water samples.The method has the advantages of simple operation,low cost and fast phase separation,showing good reproducibility and high recovery for analytes.Chapter 3: An effervescence-assisted dispersive liquid-liquid microextraction method was established for the determination of environmental estrogens in water samples by HPLC / UV.Sodium carbonate and sodium dihydrogen phosphate were used to produce carbon dioxide as the driving force to disperse the extraction agent quickly and evenly in the water sample to achieve the effective extraction of the analytes.In this study,the composition and total amount of effervescent agent,the protocol of adding effervescent agent,the type and volume of extractant,the effect of pH value on the extraction efficiency were optimized and the method was evaluated systematically.The optimum extraction conditions were as follows: 0.35 g of sodium carbonate and sodium dihydrogen phosphate as the effervescent agent was placed at the bottom of the tube,and 60 ?L of carbon tetrachloride was added.Under the optimum conditions,the linear ranges for the two analytes were 5-200 ng / m L.The recoveries were between 81.5 and 102.8 %,and the relative standard deviations were in the range of 0.90-4.4 %.The established method has been successfully used for the analysis of sea water,well water and drinking water.In this experiment,quick extraction could be performed without use of organic dispersant.Therefore,the proposed method is simple,time-saving,low-cost and environmental-friendly.