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991.
992.
Hans Malfatti 《Fresenius' Journal of Analytical Chemistry》1893,32(1):754-761
Ohne Zusammenfassung 相似文献
993.
994.
K. Pittertschatscher Norbert Inreiter Andrea Schatzl Hans Malissa 《Fresenius' Journal of Analytical Chemistry》1999,365(4):338-350
A new multiclass/multiresidue method for monitoring plant protectant residues in raw- and drinking waters with on-site sampling
using a mobile, self-contained sampling unit based on SPE was developed and validated. 38 active compounds with widely varying
chemical and physicochemical properties (acid-base properties, polarities, vapor pressures, solubilities) are measured from
just one sample and work-up. 100 mL water, acidified with acetic acid, are drawn through a cartridge filled with Amberchrom
resins by means of a calibrated 100 mL syringe driven by servo motors, control circuit and rechargeable battery. Volumetric
flow is high, quantitative extraction of acidic, neutral and weak basic substances is accomplished in a few minutes and loaded
cartridges are transported into the laboratory. Further work-up, i.e. elution, drying, concentration and solvent change, is
designed strictly non-selectively and produces 250 μL of an “extract”, which is the starting point of two GC measurement lines,
GC-NPD and GC-ECD. Chlorinated herbicide acids are derivatised into perfluorinated benzyl esters employing reaction conditions
so smooth that the organochlorine hydrocarbons are not destroyed at all and both substance classes can be chromatographed
in one GC run. ECD-chromatograms from derivatised solutions are rather complex, therefore the flow is split after injection
onto two columns with different polarities and two EC-detectors in order to resolve all analytes and matrix interferents.
Short-chain carbonic acids added to the water prior to preconcentration are adsorbed on the hydrophobic surface in a reversible
process and impart the Amberchrom resins with a partially hydrophilic character. Method performance was ascertained using
tap water fortified at the 0.2 μg L–1 level: Mean recoveries were between 70 and 115% and method detection limits (MDLs) below 0.08 μg L–1. Waters from different sources did not affect the recoveries, loaded cartridges are stable for two weeks’ storage when cooled.
Received: 28 December 1998 / Revised: 20 April 1999 / Accepted: 13 May 1999 相似文献
995.
996.
997.
998.
Hans TRIEBEL 《数学学报(英文版)》2008,24(4):539-554
A space Apq^s (R^n) with A : B or A = F and s ∈R, 0 〈 p, q 〈 ∞ either has a trace in Lp(Г), where Г is a compact d-set in R^n with 0 〈 d 〈 n, or D(R^n/Г) is dense in it. Related dichotomy numbers are introduced and calculated. 相似文献
999.
Ohne ZusammenfassungMitteilung Nr. 50. 相似文献
1000.
Mindaugas Radziunas Vasile Z. Tronciu Uwe Bandelow Mark Lichtner Martin Spreemann Hans Wenzel 《Optical and Quantum Electronics》2008,40(14-15):1103-1109
Theoretical and experimental investigations have been carried out to study the spectral and spatial behavior of monolithically integrated distributed-feedback tapered master-oscillators power-amplifiers emitting around 973 nm. Introduction of self and cross heating effects and the analysis of longitudinal optical modes allows us to explain experimental results. The results show a good qualitative agreement between measured and calculated characteristics. 相似文献