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A restricted access material (RAM), alkyl-diol-silica (ADS), was used to prepare a highly bio-compatible solid-phase microextraction (SPME) capillary for the automated and direct in-tube extraction of several benzodiazepines from human serum. The bifunctionality of the ADS extraction phase prevented fouling of the capillary by protein adsorption while simultaneously trapping the analytes in the hydrophobic porous interior. This the first report of a restricted access material utilized as an extraction phase for in-tube SPME. The approach simplified the required apparatus in comparison to existing RAM column switching procedures, and more importantly eliminated the excessive use of extraction solvents. The biocompatibility of the ADS material also overcame the existing problems with in-tube SPME that requires an ultrafiltration or other deproteinization step prior to handling biological samples, therefore further minimizing the sample preparation requirements. The calculated oxazepam, temazepam, nordazepam and diazepam detection limits were 26, 29, 22 and 24 ng/ml in serum, respectively. The method was linear over the range of 50-50 000 ng/ml with an average linear coefficient (R2) value of 0.9998. The injection repeatability and intra-assay precision of the method were evaluated with five injections of a 10-microg/ml serum sample (spiked with all compounds), resulting in an average RSD<7%. The ADS extraction column was robust, providing many direct injections of biological fluids for the extraction and subsequent determination of benzodiazepines. 相似文献
113.
Dieter H. Mayer 《Journal of statistical physics》1985,38(3-4):785-803
We derive universal scaling properties for k–1 actions on the circle whose generators have rotation numbers algebraic of degreek. As fork=2 these properties can be explained for arbitraryk in terms of a renormalization group transformation. It has at least one trivial fixed point corresponding to an action whose generators are pure rotations. The spectrum of the linearized transformation in this fixed point is analyzed completely. The fixed point is hyperbolic with a (k–1)-dimensional unstable manifold. In the casek=2 the known results are therefore recovered. 相似文献
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Prakash R Czaja AU Heinemann FW Sellmann D 《Journal of the American Chemical Society》2005,127(40):13758-13759
The new ruthenium compound [Ru(NO)(pysiS4)]Br (3) (pysiS4 = 2,6-bis(3-triphenylsilyl-2-sulfanylphenylthiomethyl)pyridine), containing sterically bulky SiPh3 groups ortho to the thiolate donors, has been synthesized. In solution, 3 releases NO efficiently on exposure to visible light (lambda >/= 455 nm) at room temperature to afford [Ru(Br)(pysiS4)] (4). Treatment of 4 with NO yielded exclusively 3 without any metal-bound side reaction. 相似文献
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Roland Boese Dieter Bläser Michael Nussbaumer Tadeusz Marek Krygowski 《Structural chemistry》1992,3(5):363-368
The crystal and molecular structure of nitrobenzene was determined at 103 K by X-ray diffraction, yieldingR=0.034 and a highly precise geometry of the molecule (esds of bond lengths 0.001 Å and bond angles 0.1°). The bond angles in the ring agree very well with additive scheme based on angular substituent parameters. X-X electron density maps support the view that the C-N bond does not exhibit-character, and, hence, the nitro group interacts with the ring mostly by inductive effects. 相似文献
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The carrier mediated transport of cations using model compounds of the verdinoid and rubinoid bile pigment structural type as ionophores is studied. Verdinoid bile pigments turn out to be very effective carriers for cations exhibiting a pronounced selectivity for certain transition metal ions like Cr+-+, Fe++, Cu++ and Zn++. The scope of this behaviour of verdinoid bile pigments is compared to [18]-crown-6 and meso-tetraphenylporphin and is discussed with regard to structural, biological, analytical and technical implications. 相似文献