Metal-Organic Framework For Solid-Phase Microextraction Of VOCs In Exhaled Breath Of Diseases And Water Samples

Volatile organic compounds（VOCs）are the main organic pollutants in rivers,air and underground drinking water.The main source is the continuous emissions from chemical plants,pharmaceutical factories,transportation and other industries,posing a great threat to the ecological environment and human health.The changes of VOCs concentration in human exhaled breath are closely related to the occurrence of major diseases,so the detection of VOCs in human exhaled breath can be used as a clinical basis for early diagnosis of diseases.Due to the low content of VOCs in actual samples and the complex sample matrix,an efficient and fast sample pretreatment method is needed to enrich the target to detect its concentration directly.Solid-phase microextraction（SPME）technology has the characteristics of low organic solvent consumption,simple operation and easy linkup with detection instruments,and is widely used in the enrichment of target in environmental,biological,food and other samples.SPME is based on the material distribution equilibrium of the analytes between the sample matrix and the coating material.Therefore,the coating material plays an important role.Metal organic frameworks（MOFs）are a kind of hybrid materials with porous network structure formed by self-assembly of metal ion centers and organic ligands through coordination bonds.MOFs featuring large specific surface area,adjustable pore size,excellent stability and post-modification have good application prospects as coatings in SPME.Based on the above discussion,this paper aims to explore the application of MOFs and their composite materials as SPME coating,combined with GC/GC-MS technology for the enrichment of biomarkers in the exhaled breath of cancer patients and benzene series in the water environment.The main innovations and research contents are as follows:1.ZIF-8-90 coated SPME fibers were prepared by sol-gel method and used for the enrichment of eight VOCs（ethanol,acetone,hexanal,hexanol,nonane,isoprene,heptane and decane）in the exhaled breath of healthy volunteers and gastric cancer patients.The prepared materials were characterized by XRD,TGA,SEM,FT-IR and N₂adsorption.After optimizing the extraction parameters,we compared the extraction capacity of ZIF-8-90 with ZIF-8,ZIF-90 coated fiber and commercial extraction fibers under the optimal extraction conditions.The coordination effect of the hydrophilic and hydrophobic ligands of ZIF-8-90material has good extraction efficiency for both polar and non-polar targets,making the coating have a very good application prospect in the early diagnosis of gastric cancer.2.MIL-53（Fe）-NH₂coating were prepared on the surface of stainless steel wire by in situ synthesis method.The composite material was characterized by XRD,TGA,SEM,TEM and FT-IR.The effects of extraction time,extraction temperature,desorption time and desorption temperature on the extraction efficiency were investigated.Under the optimal extraction conditions,it was applied to the enrichment and detection of seven VOCs（benzene,methylbenzene,hexanal,heptanal,octanal,nonanal and decanal）in the exhaled breath of lung cancer patients.This method has high enrichment factor,low detection limit and good reproducibility,can be used for early diagnosis of lung cancer,and is expected to improve the survival rate of patient.3.In order to improve the water stability of MOF and expand its application in water environment samples,composite materials ZIF-67@MON（Microporous Organic Network）with hydrophobic surface was formed through sonogashira coupling reaction and SPME fiber is prepared by the adhesive method.The ZIF-67@MON material was characterized by XRD,TGA,SEM,TEM and FT-IR.Then,the effects of extraction time,extraction temperature,desorption time,desorption temperature,stirring rate and salt concentration on the extraction efficiency of BTEX in water environment sample were investigated.The adsorption performance of ZIF-67@MON and the ZIF-67 coating for benzene series were compared under the optimal experimental conditions.The strong hydrophobic interaction andπ-πinteraction between MON and BTEX improved the extraction capacity of ZIF-67@MON,and it was successfully used for pre-enrichment of BTEX in river samples.