Browsing by Subject "high performance liquid chromatography"
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Item Open Access Bioremediation of 2,4,6-Trinitrotoluene by novel strains of aerobic bacteria(2012) Gümüşcü, Burcu2,4,6-Trinitrotoluene (TNT) has been used extensively for military purposes since its invention in the late 19th century. TNT is a highly toxic and recalcitrant substance due to its multiple nitrated molecular configuration. TNT residues can enter biological systems and constitute a significant risk to human health. To this end, biological approaches promise great potential for removal of TNT in both aqueous and terrestrial environments by the usage of microorganisms. However, remediation capabilities of these organisms are limited due to their inadequate survival and degradation capacity in the environment. To address these issues, we investigated and demonstrated high degradation performance of novel bacterial strains isolated from TNT-contaminated sites, Citrobacter murliniae STE 10, Achromobacter spanius STE 11, Kluyvera cryocrescens STE 12, and Enterobacter amnigenus STE 13, for an enhanced remediation process. In the first part of this thesis, we developed a novel HPLC method on a Diol-functionalized chromatography column for accurate, rapid, economic, and environmentally friendly detection of nitroaromatic compounds. Data obtained from chromatography measurements clearly verified that the minimum limit of detection values for TNT and TNT metabolites (0.78-1.17 µg/L) were lower than the values obtained by previous reports and the widely used EPA method. In the second part, for the first time, we achieved rapid (less than 20 h) TNT decontamination using novel bacterial strains under aerobic conditions at 99.9% efficiency. We showed that TNT was transformed into less toxic and highly reactive metabolites. The data obtained from elemental analysis and HPLC measurements together with FT-IR results indicated that approximately 71.42% of nitrogen from TNT is accumulated in the biomass. In the third part, we designed laboratory-scale compost system for optimization of maximum TNT degradation efficiency. In this study, we observed a strong correlation between degradation capacity of microorganisms and carbon/nitrogen (C/N) ratio, air flow, and TNT amounts. We accomplished a complete TNT degradation (100%) by an in-vessel compost system in 15 days, the shortest period ever reported. These bioremediation approaches hold great promise for efficient and sustainable removal of TNT for safe environment.Item Open Access In situ synthesis of biomolecule encapsulated gold-cross-linked poly(ethylene glycol) nanocomposite as biosensing platform: A model study(Elsevier BV, 2010) Odaci, D.; Kahveci, M.U.; Sahkulubey, E.L.; Ozdemir, C.; Uyar, Tamer; Timur, S.; Yagci Y.In situ synthesis of poly(ethylene glycol) (PEG) hydrogels containing gold nanoparticles(AuNPs) and glucose oxidase (GOx) enzyme by photo-induced electron transfer process was reported here and applied in electrochemical glucose biosensing as the model system. Newly designed bionanocomposite matrix by simple one-step fabrication offered a good contact between the active site of the enzyme and AuNPs inside the network that caused the promotion in the electron transfer properties that was evidenced by cyclic voltammetryas well as higher amperometric biosensing responses in comparing with response signals obtained from the matrix without AuNPs. As well as some parameters important in the optimization studies such as optimum pH, enzyme loading and AuNP amount, the analytical characteristics of the biosensor (AuNP/GOx) were examined by the monitoring of chronoamperometric response due to the oxygen consumption through the enzymatic reaction at − 0.7 V under optimized conditions at sodium acetate buffer (50 mM, pH 4.0) and the linear graph was obtained in the range of 0.1–1.0 mM glucose. The detection limit (LOD) of the biosensor was calculated as 0.06 mM by using the signal to noise ratio of 3. Moreover, the presence of AuNPs was visualized by TEM. Finally, the biosensor was applied for glucose analysis for some beverages and obtained data were compared with HPLC as the reference method to test the possible matrix effect due to the nature of the samples.