Analysis Of Persistent Organic Pollutants By Surface Enhanced Raman Spectrometry And Electrochemical Immunoassay

With the rapid progress of science and technology, more and more persistentorganic pollutants (POPs) are released by industrial manufacture, which poses a threat toboth natural environment and human health. Now, POPs have become one of worldwideenvironmental problem which have much attention. At present, researches of monitoringPOPs are mostly based on large instruments such as gas/liquid chromatography andchromatography-mass spectrometry. However, their costly and time-consumingprocedures make them unsuitable for rapid and real-time test. Thus, developing methodsfor quick analysis of POPs is of great significance.Surface enhanced Raman spectrometry and electrochemical immunoassay are rapidanalytic methods with high sensitivity, which are regarded as the new detecting means oflarger potential for applications. This thesis selected three typical organic pollutants asthe research objects including pyrene, tris(2,3-dibromopropyl) isocyanurate (TBC) andoctachlorostyrene (OCS), and developed three types of methods based on SERS orelectrochemical immunoassay for quick scanning of POPs, which provides some newideas for analysis and determination of those pollutants. The main contents are asfollows:(1) Surface enhanced Raman spectroscopic detection of pyrene using silvernanoparticle-chitosan multilayer substrates: A silver nanoparticle/chitosan/TiO2composite nanomaterial was prepared based on repeatedly self-assembly betweenchitosan molecules and silver nanoparticles through electrostatic force. When targetmolecules were captured by the choitosan and brought close to the hot spots generatedby silver nanoparticles embeded in the substrate, significant Raman enhancement effectswere observed. Pyrene can be detected in the range from0.05to10μM with thedetection limit of0.01μM. The recovery rates of real samples show an acceptableaccuracy, indicating this substrate provides a new platform for detection of pyrene.(2) Proposed a highly sensitive electrochemical immunosensor for the rapiddetection of TBC: TBC derivative was first conjugated with ovalbumin, and theconjugates were immobilized on electrode surface through a chitosan membrane tocompete with free TBC in solution for specific immunoreaction with the anti-TBCantibody, followed by the immobilization of horseradish peroxidase (HRP)-labeledsecondary antibody. Finally, with the addition of H2O2and hydroquinone, the changes in the cathodic current were recorded. Under optimal conditions, TBC can be detected inthe detection limit of8.6nM. The proposed HRP-labeled electrochemical immunosensorexhibited good precision, sensitivity, selectivity, and storage stability, which embodiesthe prospect of application in monitoring TBC in real samples.(3) Proposed an immunosensor using gold nanoparticle as an electrochemical labelfor sensitive detection of OCS: Gold naonoparticles with large diameter (AuNPs) wereintroduced to act as an electrochemical label while gold naonoparticles with smalldiameter (nanao-Au) were used to construct a composite membrane support on electrode,which provide a larger specifc surface for self-assembly of anti-OCS antibody tomagnify signals. Based on an indirectly competitive immunoreaction, the antigenslabeled by AuNPs competed with target OCS molecules in sample for specificimmunoreaction with the limited molecules of antibodies, followed by electrochemicallyanalytical procedures of adsorptive voltammetry, giving a determination limit of0.4nM.The proposed electrochemical immunoassay exhibited good precision, sensitivity,selectivity, storage stability and obtained satisfactory results in the analysis of realsamples.