排序方式: 共有31条查询结果,搜索用时 9 毫秒
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Ralf Eiden Ralf Falter Barbara Augustin-Castro Heinz Friedrich Schöler 《Analytical and bioanalytical chemistry》1997,357(4):439-441
Distillation as a way of sample digestion has been combined with on-line RP C18 preconcentration and HPLC-UV-PCO-CVAAS (high
performance liquid chromatography – ultra violet – post column oxidation – cold vapour atomic absorption spectrometry) for
the determination of methylmercury at background levels in sediments, soils and fish tissue. To prove the accuracy of this
method, it was applied to sediment and fish tissue reference materials. The results correspond with the reference values within
their error ranges. Excellent recoveries (92–95%) were obtained for the sediment samples by means of the standard addition
method. The standard deviations of the sediment samples were within an acceptable range (7.2–12.5%), those of the fish samples
were substantially lower (3.4–5.0%). The detection limit is 0.04 ng/g for 1 g sample weight.
Received: 23 November 1995/Revised: 16 April 1996/Accepted: 20 April 1996 相似文献
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G. C. Eiden M. E. Cisper M. L. Alexander P. H. Hemberger N. S. Nogar 《Journal of the American Society for Mass Spectrometry》1993,4(9):706-709
Laser desorption in an ion trap mass spectrometer shows significant promise for both qualitative and trace analysis. In this work, we explore various combinations of time-varying DC and radiofrequency (RF) fields in order to optimize laser-generated signals. By judicious choice of timing between the laser desorption pulse and the rise in the applied RF trapping potential, we observed over an order of magnitude enhancement in the trapped ion signal. This new method for laser desorption has enabled us to observe mass spectra of many compounds (e.g., pyrene, dichlorobenzene, and ferrocene) that are barely detectable using previous laser desorption methods. Effects of laser timing and the magnitude of the steady-state RF potential are discussed. 相似文献
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Martin TC Moecks J Belooussov A Cawthraw S Dolenko B Eiden M Von Frese J Kohler W Schmitt J Somorjai R Udelhoven T Verzakov S Petrich W 《The Analyst》2004,129(10):897-901
Signatures of Bovine Spongiform Encephalopathy (BSE) have been identified in serum by means of "Diagnostic Pattern Recognition (DPR)". For DPR-analysis, mid-infrared spectroscopy of dried films of 641 serum samples was performed using disposable silicon sample carriers and a semi-automated DPR research system operating at room temperature. The combination of four mathematical classification approaches (principal component analysis plus linear discriminant analysis, robust linear discriminant analysis, artificial neural network, support vector machine) allowed for a reliable assignment of spectra to the class "BSE-positive" or "BSE-negative". An independent, blinded validation study was carried out on a second DPR research system at the Veterinary Laboratory Agency, Weybridge, UK. Out of 84 serum samples originating from terminally-ill, BSE-positive cattle, 78 were classified correctly. Similarly, 73 out of 76 BSE-negative samples were correctly identified by DPR such that, numerically, an accuracy of 94.4 % can be calculated. At a confidence level of 0.95 (alpha = 0.05) these results correspond to a sensitivity > 85% and a specificity > 90%. Identical class assignment by all four classifiers occurred in 75% of the cases while ambiguous results were obtained in only 8 of the 160 cases. With an area under the ROC (receiver operating charateristics) curve of 0.991, DPR may potentially supply a valuable surrogate marker for BSE even in cases in which a deliberate bias towards improved sensitivity or specificity is desired. To the best of our knowledge, DPR is the first and--up to now--only method which has demonstrated its capability of detecting BSE-related signatures in serum. 相似文献
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M. Liezers M. C. Endres A. J. Carman G. C. Eiden 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(1):71-80
In this work, a brand new organic superficial active sorbent l-Cysteine hydrochloride modified bentonite (LCMB) has been developed and proposed for treatment of contaminated water containing uranium. Correlation between different factors such as pH, contact time, temperature, initial concentration of U(VI) and efficiency of LCMB for uranium absorption are discussed. At uranium content in water from 25 to 250 mg L?1, the sorption capacity for LCMB reached 208.3 mg g?1 that is essentially higher in comparison with other sorbents and notably improved from 77 mg g?1 after modification. 相似文献
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Michael Dion Greg Eiden Orville Farmer Zach Finch Martin Liezers 《Journal of mass spectrometry : JMS》2016,51(8):591-595
A technique that uses the intrinsic mass‐based separation capability of a quadrupole mass spectrometer has been used to resolve spectral radiometric interference of two isotopes of the same element. In this work the starting sample was a mixture of 137Cs and 134Cs and was (activity) dominated by 137Cs. This methodology separated and ‘implanted’ 134Cs that was later quantified for spectral features and activity with traditional radiometric techniques. This work demonstrated a 134Cs/137Cs activity ratio enhancement of >4 orders of magnitude and complete removal of 137Cs spectral features from the implanted target mass (i.e. 134). Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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M. Liezers G. C. Eiden A. J. Carman 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(1):55-68
Heavy metals and radionuclides were investigated in the northern coastal zone of Ikaria Island. The collected sediment samples are sandy and they contain distinct heavy metal- and actinide-hosting minerals. All samples exhibit low U and Th content relative to granitic rocks of Aegean islands. The enrichment factor indicates an anthropogenic enrichment in As and Pb due to boat pigments. The radioactivity is mainly attributed to 40K (up to 1480 Bq kg?1) and 232Th radionuclide series. The natural radioactivity of the northern coastal zone is lower compared to that of the southern coast where renowned thermal springs are located. 相似文献
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