Isolation And Determination Of Marine Organic Pollutants And Paralytic Shellfish Poisoning Toxins Based On Molecularly Imprinted Solid-phase Extraction

Molecularly imprinted polymers (MIPs) are synthetic materials with artificiallygenerated recognition sites able to specifically rebind a target molecule in preferenceto other closely related compounds. MIPs have been employed in fields where acertain degree of selectivity is required such as environmental monitoring, food safety,natural products separation and chromatographic analysis. However, nowadays theiruse in solid-phase extraction, so-called molecularly imprinted solid-phase extraction(MISPE), is by far the most advanced technical application of MIPs. This dissertationtakes typical marine organic pollutants and PSP toxins as the research objects. MIPswere prepared by molecular imprinting technology (MIT), used as solid-phaseextraction sorbents, and then combined to off-line analytical techniques for thedetection of typical marine pollutants and PSP toxins.As following was primary research to be acquired in the dissertation:1） Molecularly imprinted polymers were prepared by the bulk polymerizationusing triphenylmethane dyes (malachite green and crystal violet) as the templatemolecule. Systematic investigations of synthetic conditions were conducted. Thesurface morphology and recognition mechanism of the obtained polymers werestudied using scanning electron microscope, FT-IR and spectrophotometric analysis.MIPs showed high affinity to template molecule and were successfully applied asspecial solid-phase extraction sorbent for selective extraction of triphenylmethanedyes from natural seawater and seafood samples. An off-line MISPE method followedby HPLC with diode-array detection for the analysis of triphenylmethane dyes wasalso established. The extraction on MIPs column can successfully cleanupcomplicated matrix, allowing the extraction of the target with high selectivity.2） In this chapter, a highly selective sample cleanup procedure combined withMISPE was developed for the isolation of sulfadiazine in seawater samples fromJiaozhou Bay, China. The MIP was prepared using sulfadiazine as the templatemolecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linking monomer. The MIP was used as selective sorbentfor the solid-phase extraction of sulfadiazine. An off-line MISPE method followedby HPLC with diode-array detection for the analysis of sulfadiazine was established.Good linearity on MISPE column for sulfadiazine standard solutions was obtainedwithin0-200μg L1(R2>0.99). The recoveries of spiked seawater samples were in therange79.17%-86.54%. Finally, seven samples in Jiaozhou Bay were determined andthere was no sulfadiazine found except No.2and No.5sample. SDZ was found inwestern area of Jiaozhou Bay. This may be caused by the mariculture, and mostfarming locate in the western part of Jiaozhou Bay.3） Paralytic shellfish poisoning (PSP) is a potentially fatal human healthcondition that may occur after the consumption of PSP toxins contaminated shellfish.The toxins are produced predominantly by dinoflagellates. Gonyautoxins are commonof PSP toxins in China sea. In view of the high toxicity and cost of the target, dummyimprinting is a viable strategy for the synthesis of MIPs. In this chapter, molecularlyimprinted polymer microspheres (MIPMs) for gonyautoxins2,3were preparedthrough suspension polymerization method using caffeine as the dummy templatemolecule, methacrylic acid as the functional monomer, ethylene glycol dimethacrylateas the cross-linker and polyvinyl alcohol as the dispersive reagent. Systematicinvestigations of synthetic conditions were conducted and equilibrium bindingexperiments were performed. The surface morphologies of polymers were studied byusing SEM and BET. The results show that the obtained MIPMs showed high affinityto gonyautoxins2,3and this study will provide the research foundation for the nextseparation and isolation of gonyautoxins2,3from dinoflagellate Alexandrium.A new and selective sorbent for MISPE was developed for the isolation ofgonyautoxins2,3from dinoflagellate Alexandrium minutum and A. tamarense sample,and validated by HPLC coupled to fluorescence detection. The molecularly imprintedpolymer microspheres were prepared by precipitation polymerization using caffeineas the dummy template molecule and polyvinyl alcohol as the dispersive reagent. Theimprinted polymer microspheres exhibited high affinity, selectivity for gonyautoxins2,3and used as a selective sorbent for the solid-phase extraction of gonyautoxins2,3.An off-line MISPE method was established and good linearity on MISPE column forthe gonyautoxins2,3standard solutions was obtained within0-20μg L1(R2>0.99). Furthermore, the extract samples from A. minutum and A. tamarense were analyzed.The results showed the interferences matrix in the extract were obviously cleaned byMISPE. The extraction efficiency of gonyautoxins2,3exceeded80%. The obtainMIPMs could be used up to7times after a short regeneration step and maintainedtheir adsorption capacity at an almost constant value.