Adsorption of Triazine Derivatives in Hexane and Large-Scale Enrichment of Chlorinated Triazine Derivatized Sulfur-Containing Acid in Acetonitrile with Humic Fraction-Immobilized Silica Gel
| Autor: | Shun-Wei Hu, 胡順惟 |
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| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 A fraction of humic acid is collected under acidic conditions, then immobilized on silica gel and used as the adsorbent for various symmetrical triazine (s-triazine) derivatives in hexane. The enhanced hydrogen bonding between the analyte and humic fraction molecules, not the complexation interaction, is responsible for the adsorption observed in hexane, based on Fourier transform infrared (FTIR) spectroscopy results. The percentage of adsorption in hexane for all s-triazine derivatives reaches nearly 100% in 1 h, independent of the type, position, and size of the substituent on the aromatic nitrogen heterocyclic ring. Other factors leading to the variation of the percentage of adsorption include the type of liquid phase and the additive of acidic or basic origin present in the matrix. Previous studies have demonstrated that adsorption mechanism of triazine derivatives with humic fraction-immobilized silica gel in hexane. Adsorption mechanism is applied to the study.The analog of triazine is used as the derivatizing reagent for enriching large-scale acid (e.g. amino acid) containing a sulfur atom on the humic-fraction-modified silica gel in acetonitrile and desorbing from the adsorbent in hexane, respectively. The percent yield of the chemical derivatization under alkaline conditions, ranging from about 8 to almost 100%, and varies significantly among these examined analytes, believed to be due to the structure of the analyte, not the derivatizing reagent. The percentage of enrichment, not reproducible under an aqueous environment and independent of the type of triazine analogs, reaches almost 100% in all cases. The force leading to the adsorption is the complexation between carboxyl groups on analyte and a humic-fraction-modified adsorbent based on the adsorption equilibrium results. Consequently, these results are not reproducible under ethyl ether or methanol environments due to the competition for binding sites from solvent molecules. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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