| Several kinds of novel graphene composites by hydrothermal synthesis have been prepared and set as adsorbents. A novel online solid phase extraction disk (Online-Disk) has been designed and developed for the analysis of trace organic pollutants. The established Online-Disk methods reveal the advantages including simple operation, high sensitivity, good reproducibility, environment-friendly, and well-coupled with high performance liquid chromatography. The Online-Disk has successfully been applied in the quantitative analysis of heterocyclic aromatic amines in beef jerky and the migration of bisphenol A from disposable syringes.This dissertation includes five chapters.Chapter I, introduction. Some research backgrounds of solid phase extraction including adsorption mechanism, sorts of stationary phase, apparatus, extraction mode and their applications have been reviewed. The synthesis and applications of graphene and its composite materials have been summarized, and the advantages of diode array detector followed by high performance liquid chromatography (HPLC-DAD) have been discussed. The train of thought of the study was put forward.Chapter II, the preparations of graphene composites and construction of the Online-Disk system has been introduced, in which self-made graphene oxide was taken as a raw material, and functionalized-or modified with metal nanometer materials or compounds with special groups by hydrothermal reduction. Using the method, the reduced graphene oxide-gold (RGO-Au), reduced graphene oxide-iridium (RGO-Ir) and reduced graphene oxide modified with phosphoric acid (RGO-PA) have been obtained. The graphene composites have been characterized to reveal the reasons their excellent special physical and chemical properties. A new Online-Disk with modified-RGO materials has been developed. Without the addition eluent, the mobile phase used in HPLC can be acted as the eluent for the Online-Disk applications, which simplify the sample preparation and improves the detection sensitivity. Chapter III, the application of the Online-Disk composing reduced graphene oxide-gold for the analysis of heterocyclic aromatic amines (HAAs) has been proposed. Different kinds of adsorbents including RGO, RGO-Au, RGO-Ir, graphite carbon nitride (g-C3N4) and commercial PRS (silica based adsorbents bonded with propyl sulfonic acid functional groups) have been compared for the extraction of HAAs. Due to the supporting of nano metal particles, three-dimension RGO-Au and RGO-Ir have been found to be the best adsorbents for the enrichment of HAAs. An Online-Disk filled with RGO-Au has been used as a superior pre-concentrate unit combined with a HPLC-DAD and applied in the determination of the trace amount of HAAs in beef jerky samples. The RGO-Au Online-Disk reveals advantages as simple, rapid, high sensitive, accuracy and inexpensive. The linear range for HAAs is found to be in the range from0.1to500ng·g-1, with the method detection limits from0.09to0.16ng·g-1and recoveries with70to117%. The contains of HAAs in three beef jerky samples have been found in the range of0.58-17.61ng·g-1Chapter IV, the analytical approach for the determination of bisphenol A using an Online-Disk modified with RGO-PA has been developed. RGO and g-C3N4have been used to compare the extraction ability of bisphenol A, and RGO-PA reveals the best adsorptive properties among them. An Online-Disk filled with RGO-PA has been applied in the monitoring of bisphenol A migration in disposable syringes, which launchs a new quick, easy and solvent-free enrichment method for the determination of bisphenol A in water samples. The linear range for bisphenol A has been found in the range from1to1000ng·mL-1, with the detection limit of0.03ng·mL-1and recoveries from73to117%. Bisphenol A could be detected in disposable syringe samples, with the migration amount from ca4x10-5to2.84x10-3mg·dm-2, which is lower than the permissible values of GB9685-2008.Chapter V, the research work results in the dissertation are summarized and the future prospect of Online-Disk is presented. |
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