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Erscheinungsjahr
- 2017 (2) (entfernen)
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- Englisch (2)
Referierte Publikation
- ja (2) (entfernen)
Schlagworte
- Advanced oxidation (1)
- GC-MS (1)
- Heterogeneous photocatalysis (1)
- Metformin (1)
- Methylene blue (1)
- Nanozirconia (1)
- Surface water (1)
- Water treatment (1)
Drug therapy for diabetes mellitus has increased significantly in recent years. 1,1-Dimethylbiguanide hydrochloride (metformin) is the most common drug used for the treatment of diabetes. Metformin is not metabolized in the human body and enters thewater cycle via sewage.
A new gas chromatography-mass spectrometry (GC-MS) method has been developed which enables the quantification of metformin in surface water samples even at low concentrations in the ng L-1 range.
A solid phase extraction (SPE) method for the preconcentration of metformin and the internal standard 1-butylbiguanide (buformin) was established, and the method parameters such as the composition and volume of the eluent were optimized. Derivatization of metformin and
buformin was obtained by using n-methyl-bis (trifluoroacetamide)(MBTFA). The reaction conditions of the derivatization, such as the reaction temperature and volume of the derivatization agent, were evaluated. The limit of detection (LOD) and limit of quantification (LOQ) were determined to be 3.9 ng L-1 and 12 ng L-1 in surface water samples. Linearity was shown over a concentration range of 10–50 ng L-1. The good performance of the method was demonstrated by comparison with a liquid chromatography tandemmass spectrometry (LC-MS/MS) method. The results indicate that the GC-MS method is a reliable and sensitive alternative for the quantification of metformin in surface water.
1.
Nano-TiO2 powder is known to show high photocatalytic reactivity in the degradation of several organic pollutants.
In thiswork, the powderwas fixed on the surface of SiO2 granuleswith the size of several micrometers using a high shear granulation process. Nanozirconia sol was applied as an inorganic binder. When the samples were tempered at 300 °C, they showed high stability in an aqueous solution for several hours. An energy dispersive x-ray spectroscopy (EDX) analysis confirmed that the cores and shells of the granules consisted solely of SiO2 and TiO2 respectively, and that ZrO2 was found throughout the whole granules. Methylene blue (MB) was employed as amodel systemto evaluate the photocatalytic activity of the TiO2 nanopowder and coated granules.
Itwas shown that the TiO2-coated granules lead to the degradation ofMB under UV irradiation,whereas no effect was observed in the dark. After the Degradation experiments the granules could be recovered and they remained active for further applications.