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61.
A rapid pneumatoamperometric method for quantifying cyanide in the presence or absence of sulfide is described. The gaseous mixture of hydrogen cyanide and hydrogen sulfide is separated by inserting a short chromatographic column packed with silica gel between the reaction vessel used to generate the volatile acids and the porous gold electrode that the detects them. The detection limit is ca. 5 ng cyanide in 2 ml of solution regardless of sulfide content. The detection limit for sulfide is ca. 1.0 ng in 2 ml of solution when cyanide is present and ca. 0.7 ng in absence of cyanide. Both sulfite and nitrite interfere. 相似文献
62.
L-Carnitine is a substance natural for human body which transfers fatty acids to the place of burning-mitochondria and aids the transformation of fats into energy and this way supports overweight reduction and immediate physical performance, increases resistance from physical load and protect heart from overload. In this study are described newly developed electrophoretic methods (ITP, CZE with direct and/or indirect UV detection) for carnitine determination in various samples. The results were compared with results obtained by validated HPLC method. All of these methods gave comparable results. The detection limits of the electrophoretic methods were between 2.4 and 4.7 microg/ml, reproducibility (relative standard deviation, RSD%) was between 1.2 and 4.4% and recoveries were between 91 and 113% in different samples. The shorter analysis and low running cost are the main advantages of CE methods. 相似文献
63.
Hongxiang Teng Liang Yang Frantisek Mikes Yasuhiro Koike Yoshiyuki Okamoto 《先进技术聚合物》2007,18(6):453-457
Copolymers of methyl methacrylate (MMA) with 2,3,5,6‐tetrafluorophenyl methacrylate (TFPMA), pentafluorophenyl methacrylate (PFPMA), and 4‐trifluoromethyl‐2,3,5,6‐tetrafluorophenyl methacrylate (TFMPMA) were investigated. All the three systems showed a random copolymerization character. The composition, glass transition temperature (Tg), and refractive index of the copolymers obtained were studied. Tgs of TFPMA/MMA and PFPMA/MMA copolymers were found to deviate positively from the Gordon–Taylor equation. However, Tgs of TFMPMA/MMA copolymers were well fit with the Gordon–Taylor equation. These results indicated the existence of interaction between MMA and either TFPMA or PFPMA units in copolymers. This interaction resulted in the enhancement of the Tg of MMA polymers through the copolymerization with TFPMA and PFPMA. The refractive index and the light transmittance of copolymers were close to those of PMMA. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
64.
The stabilization of the reduction state of proteins and peptides is very important for the monitoring of protein-protein, protein-DNA and protein-xenobiotic interactions. The reductive state of protein or peptide is characterized by the reactive sulfhydryl group. Glutathione in the reduced (GSH) and oxidized (GSSG) forms was studied by cyclic voltammetry. Tris(2-carboxyethyl)phosphine (TCEP) as the disulfide bond reductant and/or hydrogen peroxide as the sulfhydryl group oxidant were used. Cyclic voltammetry measurements, following the redox state of glutathione, were performed on a hanging mercury drop electrode (HMDE) in borate buffer (pH 9.2). It was shown that in aqueous solutions TCEP was able to reduce disulfide groups smoothly and quantitatively. The TCEP response at -0.25 V vs. Ag/AgCl/3 M KCl did not disturb the signals of the thiol/disulfide redox couple. The origin of cathodic and anodic signals of GSH (at -0.44 and -0.37 V) and GSSG (at -0.69 and -0.40 V) glutathione forms is discussed. It was shown that the application of TCEP to the conservation of sulfhydryl groups in peptides and proteins can be useful instrument for the study of peptides and proteins redox behavior. 相似文献
65.
Frantisek Hrabak 《Journal of polymer science. Part A, Polymer chemistry》1968,6(12):3259-3267
The isomerization of cis-1,4-polybutadiene by RhCl3 in aqueous emulsion was studied. The reaction was found to be slowed down by air and by base but not by quinone and was independent of the polymer solvents. Quinone did not suppress polymer gel formation. The results obtained suggest a nonradical mechanism of these reactions. 相似文献
66.
Frantisek Jelen Arzum Erdem Emil Palecek 《Bioelectrochemistry (Amsterdam, Netherlands)》2002,55(1-2):165-167
Interactions of echinomycin (Echi) with DNA was studied by cyclic voltammetry (CV) with hanging mercury drop electrode (HMDE). Echinomycin was electrochemically active, yielding several signals. Interaction of Echi with dsDNA attached to a hanging mercury drop electrode resulted in high Echi signals, suggesting a strong binding of Echi to dsDNA by bis-intercalation at the electrode surface. Under the same conditions, interaction of Echi with ssDNA produced almost no Echi signal. This behavior is in agreement with a strong binding of Echi to dsDNA and a very weak binding of Echi to ssDNA observed earlier in solution. Echi, thus, appears to be a good candidate for redox indicator in electrochemical DNA hybridization sensors. 相似文献
67.
Butorphanol tartrate is a synthetic opioid agonist-antagonist used as analgesic, possessing three chiral centres in the basic part of the molecule. Its chiral purity is routinely controlled only by optical rotation. A new capillary zone electrophoresis method, capable to separate the enantiomers of butorphanol and intermediate of its synthesis, cycloamine, was developed. Different electrolyte composition (type and concentration of carrier ion, pH, and organic solvent addition), and type and concentration of several chiral selectors (natural and modified cyclodextrins) were tested. Using the optimized conditions (acidic electrolyte with the addition of highly sulphated gamma-cyclodextrin) as low as 0.05% of undesirable enantiomers can be detected. Selected method characteristics, i.e., linearity (0-50 mg/l), precision (2.5% at 20 mg/l), and accuracy (101 +/- 2% at 20 mg/l) were evaluated. The optimized method was applied for the analysis of real batches of butorphanol and cycloamine. It was found that butorphanol tartrate manufactured by IVAX Pharmaceuticals contains less than 0.05% of undesirable enantiomer. 相似文献
68.
Ivo Nischang Oliver Brueggemann Frantisek Svec 《Analytical and bioanalytical chemistry》2010,397(3):953-960
Porous polymer monoliths have emerged as unique materials for many applications, including liquid-chromatographic analyses
at an unrivaled speed, solid-phase extraction, and enzyme immobilization in capillary and microfluidic chip format. This article
reviews the state of the art in the preparation of monoliths in narrow-bore capillaries and microfluidic chips and their miniaturization
under conditions of spatial confinement. New developments in their preparation mainly using free radical polymerization techniques
with a focus on morphological aspects in view of homogeneous porous materials are described. The suitability of monoliths
for analysis of both large and small molecules is also discussed. 相似文献
69.
70.
Otevrel J Mandelova Z Pesko M Guo J Kralova K Sersen F Vejsova M Kalinowski DS Kovacevic Z Coffey A Csollei J Richardson DR Jampilek J 《Molecules (Basel, Switzerland)》2010,15(11):8122-8142
In this study, a series of twelve ring-substituted salicylanilides and carbamoylphenylcarbamates were prepared and characterized. The compounds were analyzed using RP-HPLC to determine lipophilicity. They were tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Moreover, their site of action in the photosynthetic apparatus was determined. Primary in vitro screening of the synthesized compounds was also performed against mycobacterial, bacterial and fungal strains. Several compounds showed biological activity comparable with or higher than the standards 3-(3,4-dichlorophenyl)-1,1-dimethylurea, isoniazid, penicillin G, ciprofloxacin or fluconazole. The most active compounds showed minimal anti-proliferative activity against human cells in culture, indicating they would have low cytotoxicity. For all compounds, the relationships between lipophilicity and the chemical structure are discussed. 相似文献