Application Of Metal-Organic Framework Materials For Polycyclic Aromatic Hydrocarbons Analysis In Environmental Water Samples

Polycyclic aromatic hydrocarbons(PAHs) exist widely in our surrounding environment nowadays, with long-term persistence due to stable molecular structures. They may lead to DNA damage and consequent carcinogenic, mutagenic, and teratogenic effects on living beings. Therefore, PAHs have gained wide attentions and been recognized as one of the most important persistent organic pollutants(POPs). It is rather necessary to develop effective methods to monitor PAHs in the environment. However, high hydrophobic PAHs are at trace amount in environmental samples and multiple other substances are in the complex samples. Therefore, PAHs direct analysis is very difficult and pre-concentration of real samples becomes rather important. Nowadays, various pre-concentration techniques have been developed. In particular, SPE has generated wide applications considering its high recovery, low consumption of organic solvents as well as convenience for operation. Our research aims to develop novel solid-phase extraction sorbents to extract and detect PAHs in the environmental samples with high performance liquid chromatography(HPLC) coupled with fluorescence detection. The main contents are summarized as follows:1. Uniformed zeolitic imidazolate framework material ZIF-7 crystals at micrometer level have been successfully synthesized under magnetic stirring at room temperature. And the materials were utilized as sorbents in SPE analysis of PAHs in environmental water samples, followed by HPLC-FLD detection. The materials for ZIF-7 crystals are easy to gain and friendly for the environment. Moreover, there is no complicated step in the systhesis. After the o ptimizations of several factors, sensitive detection limits of 0.13-2.66 ng L-1 with relative standard deviations(RSDs) being less than 9 % have been successfully achieved. Moreover, ZIF-7 extraction also exhibited high recoveries of 78.8 % to 90.3 % with relative standard deviations(RSDs) being less than 9.4 % for PAHs in spiked environmental water samples.2. Two zeolitic imidazolate framework materials(ZIF-7 and-11) with different topologies were prepared with the same reagents in different organic solvents. Characterizations by Fourier transform infrared(FTIR) spectroscopy, X-ray diffraction(XRD) and scanning electron microscopy(SEM), indicated their successful synthesis and being suitable as solid-phase extraction sorbents. After the comparison in the same experimental conditions, ZIF-11 exhibited better extraction efficiency and was selected as SPE sorbent for PAHs analysis in environmental water samples. Under optimum extraction conditions such as sample volume, extraction time, desorption conditions, volume of organic modifier and salt concentration, the method exhibited high recoveries of 82.4 % to 112.7 % with relative standard deviations(RSDs) being less than 9% for PAHs in environmental water samples.3. Nanospheres-on-microsphere silica with core-shell structure was prepared with one-pot synthesis method at room temperature, modified with –NH2 groups, and then used as support to grow Ui O-66 nanoparticles using a facile solvothermal reaction. The synthesized silica-UIO-66 composites were further used as SPE sorbents for PAHs analysis in environmental water samples coupled with HPLC-FLD. Under optimum extraction conditions such as amount of sorbent, species and volume of organic modifier, extraction time, and salt concentration, we achieved low limits of detection of 0.04-0.40 ng L-1, high recoveries of 88.0 % to 105.1 % with relative standard deviations(RSDs) being less than 7 % for PAHs in environmental water samples.