| Most organic contaminants can accumulate in food,migrate and eventually enter the human body,causing harm to human health.As food is the main source of energy for human beings,the detection of the type and concentration of contaminants contained in it is of great significance for life safety.Due to the complexity of food matrices and organic contaminants with large difference in concentration,sample pretreatment is required to remove interfering substances before instrumental detection.Dispersive liquid-liquid microextraction（DLLME）,as a typical liquid-phase microextraction method,has been widely used because of its advantages such as rapid and green.However,traditional DLLME requires additional auxiliary means such as adding dispersant,ultrasound or centrifugation,which is complex and still cannot meet the current requirements for environmental protection.Therefore,this paper aims to develop a new DLLME that is more environmentally friendly and simple to achieve the high sensitivity for the detection of trace contaminants in food.The main work is as follows:（1）In this chapter,temperature-sensitive hyperbranched polysiloxane p（HBPSi-co-NIPAM）were synthesized using hyperbranched polysiloxanes（HBPSi）and N-isopropylacrylamide（NIPAM）.A systematic study of the phase trasition behavior by temperature-controlled UV and Laser particle size analyzer showed that phase transition temperature of p（HBPSi-co-NIPAM）was dependet on the polymer ratio,polymer concentration,ionic strength pH and target concentration,which provides theoretical support for subsequent experiments of single-factor method to optimize the polymer ratio,inorganic salt type,pH and other conditions.A novel DLLME method（TS-HBPSi-DLLME）for the detection of estrogens in milk was developed.The methodological validation showed that the extraction time was less than 5 min and recoveries ranged from 63-119%,LOD were 0.04-0.23 ng mL-1,and the RSD were all less than10.8%.Compared to conventional DLLME,TS-HBPSi-DLLME is a fast and green method without dispersant and centrifugation.（2）In this chapter,the extractant was improved,p（Ph-HBPSi-co-NIPAM）with manyπ-πand hydrophobic interaction sites was designed and synthesized according to the structural characteristics of PAHs.The contact angle measurement showed that p（Ph-HBPSi-co-NIPAM）was more hydrophobic than p（HBPSi-co-NIPAM）,and the extraction rate of p（Ph-HBPSi-co-NIPAM）for PAHs was higher after extraction performance stduy.Ph-TS-HBPSi-DLLME method was developed and successfully applied to the determination of PAHs in instant noodles through optimization of extraction conditions.The methodological validation showed that the recoveries of the method were all in the range of 87%-119%,LOD were 0.089-0.16 ng mL-1,and the RSD were all less than 9.6%. |
