Development Of Online Solid Phase Microextraction Coupled With High Performance Liquid Chromatography For Determination Of Organic Pollutants In Waters

In recent years,the research about on-line monitoring technology of pollutants has aroused the attention of scientists.Compared with the rapid development of analytical instruments,the development of sample pretreatment technology lags behind,which determines the speed and accuracy of the analysis process,and it is also a bottleneck restricting the application of online analytical instruments.Therefore,it is an urgent task in this field to design a complex sample pretreatment system with functional adsorbent material,which could achieve fast and stable characteristics in online monitoring.In this paper,several adsorbents with fast adsorption and desorption properties were synthesized.Through the NIPAM hydrogen bond and?-CD on the inclusion of small molecules,the adsorption and desorption rate of organic pollutants on the surface of SiO₂ is improved,and the rapid adsorption analysis of the material on the object is realized.The main content includes:?1?Introduction.This section reviews the different SPE pretreatment materials,sample preparation,online SPE-HPLC coupling interfaces and their advantages and limitations.Combined with the existing problems,the research significance and the main contents of this paper was proposed.?2?Constructionofonline-SPME-HPLCsystemanditsapplication.An online-SPME-HPLC system was built using the nut-type micro-packed column developed by our research group.The conditions of online enrichment time,flow rate and acetonitrile content and elution time,flow rate and eluant were optimized when C18 was used as the adsorbent.The feasibility of this system for the determination of benzene in water systems was investigated,and the reliability of this method was investigated.The results showed that the detection limits of the four targets were between 0.5².0 ng mL^-1.The spike recoveries were in the range of 78.0¹11.8%,and the RSD was less than 13%.The method can meet the requirements for the determination of benzene in water.?3?Synthesis of SiO₂ adsorption media with inclusion/temperature-sensitive dual mode of action.The surface of the SiO₂ was modified by A-?-CD and NIPAM,and then a series of pretreatment adsorbent materials SiO₂@P-?-CD/NIPAM were prepared.The structure,grafting rate and morphology were characterized by FTIR,SEM,TG and XPS to prove the grafting success.It was demonstrated that the maximum grafting ratio is 12.7%when the ratio of monomer A-?-CD to NIPAM is 1:2,and the adsorption efficiency of the adsorbent to the phenolic compound is the best by the chromatography.?4?Determination of phenolic compounds in environmental water by online SPME-HPLC method.In this part,SiO₂@P-?-CD/NIPAM was used as the adsorption medium,and an online enrichment monitoring method for phenolic compounds was established.The mechanism of rapid adsorption and desorption of analytes by adsorbents was investigated,and the feasibility of the determination of phenolic compounds?PNP,?-NP,BPA,2,4-DCP and 2,4,6-TCP?in water was investigated by online SPME-HPLC method.The conditions for on-line extraction were optimized and the reliability of the method was investigated.The results showed that the detection limits of the five analytes were between0.1⁰.7 ng mL^-1,the RSD%was less than 5.1%and the recoveries were in the range of80.0¹20.0%.