排序方式: 共有46条查询结果,搜索用时 15 毫秒
41.
Direct aqueous injection with backflush thermal desorption for wastewater monitoring by online GC-MS
W. Ziemer M. Wortberg C. Eichberger J. Gerstel W. Kerl 《Analytical and bioanalytical chemistry》2010,397(3):1315-1324
A gas chromatography—mass spectrometry system with a novel injector type, which is designed for direct aqueous injection of
wastewater, is presented. The system is used for online monitoring of the influent of the wastewater treatment plant at BASF’s
main chemical production site in Ludwigshafen, Germany. The purpose of monitoring is to protect the biological treatment process
and the receiving water body, the Rhine. The modular system is primarily based on commercial equipment, but utilizes a special
injection system, which is connected to a Deans switch. The two-stage injector consists of a programmable temperature vaporizer
(PTV) injector with a small volume insert for vaporization and a dual sorbent packed second PTV for analyte adsorption/desorption.
The Deans switch allows a backflush/thermal desorption operation which enables the direct injection of filtered, crude wastewater.
About 170 volatile and semivolatile compounds are calibrated with approximate detection limits of 1 mg/L, which are sufficient
for the analysis of untreated wastewater. The quantitative results are transferred to a database which is connected to a process
control system. If the wastewater does not meet the required specification, an alarm is generated and the wastewater is diverted
into a storage basin. Special software programs and routines allow for reliable, unattended operation and remote instrument
control. Data quality is automatically controlled in each run and through the daily analysis of quality control samples. The
current design allows for analysis of volatile compounds, such as methanol, whereas an earlier injector setup restricted the
range of analytes to less volatile compounds (of size C4 or greater). 相似文献
42.
The temperature dependence of the dipole polarizability α(λ, T) of free atoms and molecules is determined by precise measurements of the refractive index n of gases in the extended temperature range between 300 K and 1100 K for wavelength λ = 632·99 nm, using a specially constructed Michelson twin interferometer. α of the noble gases is observed to be independent of T. α of the molecular gases H2, N2, O2, and CH4 increases with increasing temperature by an amount of approximately 1 per cent per 1000 K. These results are in excellent agreement with theoretical predictions. They will be compared to previously measured temperature dependent polarizabilities. 相似文献
43.
We report experimental results on the previously unknown broadening and shifting coefficients in the fundamental and three overtone vibration-rotation bands of the HI molecule in mixtures with nitrogen gas. Our data are compared with the previously published results for the fundamental bands of the HF and HCl molecules. It is shown that the line shifts are dominated by the vibrational dependence of the isotropic part of the intermolecular interaction potential. 相似文献
44.
45.
46.
Ying Xiang Woo Lee Kornelius Nielsch Gerhard Abstreiter Anna Fontcuberta i Morral 《固体物理学:研究快报》2008,2(2):59-61
We demonstrate the fabrication of horizontally aligned and well‐defined nanopore structures by anodic oxidation of aluminum thin films and micro stripes on a Si substrate. We are able to control both, the pore diameters and interpore distances from 10 nm to 130 nm and from 30 nm to 275 nm, respectively. The anisotropy of the system induces some deviations in the pore configuration from the typical honeycomb structure. By decreasing the dimensions of the Al structures, the final pore diameter and interpore distance remains constant, enabling the transition from multiple to a few nanowire porous structures. Finally, we successfully filled the nanopores by pulsed electroplating, as demonstrated both by Scanning Electron Microscopy and by current–voltage measurements. Having full control over the size, the density, the position and the orientation of the porous structure, our approach is promising for many exciting applications, including nanoelectronics and sensing. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献