| Summary: | 碩士 === 臺灣大學 === 化學研究所 === 98 === This thesis is that we demonstrated the determination of monophosphate nucleotides through the surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using hexadecyltrimethylammonium bromide (CTAB) adsorbed gold nanoparticles (CTAB-Au NPs). The binding of four monophosphate nucleotides — adenosine 5’-monophosphate (5’-AMP), guanosine 5’-monophosphate (5’-GMP),uridine 5’-monophosphate (5’-UMP) and cytidine 5’-monophosphate (5’-CMP) — to the surfaces of these CTAB-Au NPs induced their aggregation, which allowed selective concentration of the four analytes from sample solutions. The analytes adsorbed CTAB-Au NPs were directly subjected to SALDI-MS measuremen, preventing a need of mixing the analytes with organic matrices. Our results revealed that CTAB was effective to improve ionization efficiency of the analytes and to suppress the MS background from Au clusters. By using CTAB-Au NPs that were prepared by mixing 0.4 μM CTAB with 1.8 nM Au NPs, our SALDI-MS approach provided the detection of limits at a signal-to-noise ratio of 3 of 25, 25, 5 and 10 nM for 5’-CMP, 5’-UMP, 5’-AMP and 5’-GMP, respectively. We have successfully validated the practicality of this approach through the analyses of 5’-AMP, 5’-GMP, 5’-UMP and 5’-CMP in the mushrooms extracts and of 5’-GMP in monosodium glutamate. Our approach provides advantages of simplicity, sensitivity, and reproducibility (shot-to-shot variation less than 20%) for the the determination of the concentrations of the analytes in the biological samples。
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