Applications of Thermal Lens Spectrometry (TLS) on Capillary Electrophoresis
| Autor: | Nan-Zheng Chen, 陳男政 |
|---|---|
| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 Thermal lens spectrometry is a highly sensitive detection method, which makes use of analytes to absorb laser light and produce the change of refractive index. The study based on this principle, developing a capillary electrophoresis/thermal lens absorbance method to detect non-fluorescence materials, including nanoparticles (nanogold and nanodiamond) and organic materials (malachite green and formaldehyde). The biological compatibility of nanodiamond is very good, the surface accumulates greatly and can adsorb many medicinal molecules or living creature molecules, as proteins etc... The research of nanodiamond will replace the current method that using fluorescent dye molecules to label proteins in the biomedical science. Nonetheless at present there is no ideal method to separate nanodiamond and its labeling materials. This study first used nanogold in different size to test the capillary electrophoresis/thermal lens absorbance instrumental system. Nanogold particles with average diameters of 15 and 70 nm were usefully separated by the character of its slightly negative surface. Later on with this system, non-fluorescence nanodiamond (average diameters of 35 nm) and nanodiamond adsorbing amino acids (L – lysine、glycine and L – (+) – cysteine) were also successfully separated. Among them, amino acids were individually mixed with nanodiamond by the concentration ratio 10, 100, 500, 900 to proceed CE analysis. Experimental results showed nanodiamond could adsorb amino acids that were 500 times with the gravimetric ratio. Malachite green, a non-fluorescent organic dye, that is potentially dangerous to human health, has been used illegally in the treatment of certain fish diseases, mainly, against parasites in fishwater and marine fishes. Generally the widespread examination method for malachite green is liquid chromatography/ultraviolet absorbance. Nevertheless the detection sensitivity of ultraviolet absorbance is poor and is not enough to cope with routine and low concentration examination task for malachite green. This study use thermal lens absorbance method to undergo research because the detection sensitivity can be improved with the advancement of laser power. By the use of capillary electrophoresis/on-line sample concentration, the limits of detection could be improved to 12 ppb at optimal condition. Furthermore, low concentration methanol or formaldehyde is hard to be detected by gas chromatography. The chromogenic method is the only simple examination method for methanol at present, which is that the solution containing methanol (such as color-rejected fake wines ) adding to colorless Schiff, s reagent. After heating the reactant, the color changes (The solution will be purple if methanol exists ). Yet such method is crude and highly miss-judged. It can only sift fake wines containing high concentration methanol, and isn't enough to examine whether low concentration methanol or formaldehyde exists in daily foodstuffs. This study also used capillary electrophoresis/thermal lens absorbance method and made use of green laser as light source to analyze the purple product. Experiment results showed the purple product was not unique by the traditional chromogenic method. It also found that the reaction between Schiff, s reagent and formaldehyde was complicated, and its product components varied with reaction time. This phenomenon could be proof by a lot of peaks observed from electropherograms. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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