| Summary: | 博士 === 中原大學 === 化學研究所 === 102 === In this dissertation, novel monolithic columns were developed and were applied as stationary phases for capillary electrochromatography (CEC), nano liquid chromatography (nano-LC) and sorbents for solid phase microextraction (SPME).
In the first part, triallyl isocyanurate (TAIC), ethylene dimethacrylate (EDMA), stearyl methacrylate (SMA) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) were polymerized to produce poly(TAIC-EDMA-AMPS) monolithic column and applied in nano-LC for the separation of phenolic acids. The phenolic acids were successfully separated using gradient elution for 90 min. The column efficiency was determined by using the van Deemter curve and results indicated that the plate heights was lower than 20 μm at linear flow rate of 0.1-1.0 μL/min. In comparison with the common hydrophilic monolithic column, the poly(TAIC-EDMA-AMPS) revealed more efficient in separating the phenolic acids.
In the second part, metal-organic framework (MOF) (MIL-101(Cr)) was studied as chromatographic stationary phases. At first, the MIL-101(Cr) was packed into capillary and applied in CEC system. However, due to high back pressure of MIL-101(Cr) column, attempts in applying for nano-LC system was deemed impossible. Thus, in this case, novel MOF-polymer monolith was successfully developed with improved effectiveness against high back pressure problems caused by packing. For the preparation of MOF-polymer, MIL-101(Cr), butyl methacrylate (BMA) and EDMA were homogeneously mixed in [C6mim][BF4] ionic liquid solvent via microwave assisted heating. In comparison with MOF packed column, the permeability of MOF-polymer was increased approximately to 20-fold. The MOF-polymer monoliths were characterized by scanning electron microscope (SEM), powder x-ray diffraction (PXRD), surface area analyzer and fourier transform infrared spectroscopy (FTIR).
The novel MOF-polymer monolithic columns were successfully applied for CEC, and nano-LC for several aromatic compounds, and revealed a good column efficiency and column reproducibility, respectively. Moreover, MIL-101(Cr)-polymer monolithic column was also applied in peptides analyses, the result showed that 46 peptides were identified with sequence coverage of 64 % from tryptic digest of Bovine Serum Albumin (BSA).
For the last part, MOF-polymer monoliths were applied to SPME technique for penicillins extraction, and quantitatively analyzed by CEC method to determine extraction efficiency. Using 25 wt% MOF, the desorption solvent and volume, condition solution volume, washing solution type, sample flow rate, and sample pH were optimized in the extraction of penicillin using MIL-101(Cr)-polymer as sorbent. The maximun penicillins adsorption for MIL-101(Cr) were 9.1 - 11.1 μg/mg obtained from breathrough curve.
At 25 wt%, different MOFs (cage and tunnel type) were also used to expore their extraction efficiencies. The result revealed that the recovery for cage type MIL-101(Cr) was 63.0 % - 96.2 %, while with the same cage structure MIL-100(M), the recoveries for MIL-100(Cr), MIL-100(Fe) and MIL-100(Al) were 23.9 % - 78.4 %, 7.0 % - 22.5 % and 15.6 % - 81.5 %, respectively. Meanwhile, for the tunnel type MOF, the recovery for MIL-53(Al) was 54.7 % - 67.7 %. With the results, it suggests that MIL-101(Cr) and MIL-53(Al) have greater adsorption capacities in extracting the penicillin. Further studies have conducted on MIL-101(Cr) and MIL-53(Al) by increasing the MOF wt% to 37.5. Based on the results, the recovery for MIL-53(Al) further increased to 76.4 % - 94.0 % and was comparable to MIL-101(Cr).
For MIL-101(Cr)-polymer SPME, the fabricated method exhibited a good linearity (with R2 between 0.9982 and 0.9993) from 0.01 - 1.0 μg/mL, low limits of detection (1.2 - 4.5 ng/mL), and limit of quantification (4.0 - 14.8 ng/mL). The MOF-polymer SPME was applied in river sample and the recovery ranges from 67.9 % - 91.2 % and 62.5 % - 90.8 % at spiked 0.05 μg/mL and 0.10 μg/mL concentration, respectively. Finally, the MIL-101(Cr)-polymer can be re-used at least 45 times which shows high column life-time. With these results, it showed the potential application of MOF-polymer SPME.
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