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81.
A simple, rapid and reliable capillary electrophoresis method with a photodiode array detector was developed for determination of azide as the 3,5-dinitrobenzoyl derivative in drink samples fortified with sodium azide. Sample preparation was simple and rapid because no more than a simple dilution of samples is needed after quick derivatization. Separation was carried out using a buffer system comprising 25 mM phosphate buffer and 4 mM cetyltrimethylammonium hydroxide at pH 3.0. Methyl benzoate was selected as the internal standard (IS). This study investigated the influence of the concentration of phosphate buffer and electroosmotic flow (EOF) modifier, and the buffer pH on migration time and signal response. The optimized method made it possible to determine azide within 5 min. The limit of detection was determined to be 1.9 microg/ml with SIN > 3. The quantitation range was 6.5-323 microg/ml. By the method recoveries of azide in drink samples fortified with sodium azide were investigated. Mean recovery values ranged from 93.6 to 105.8% and results were satisfactory. In addition, no interference was observed in electropherograms of drink samples fortified with sodium azide. Thus, by this method, azide in drink samples can be determined rapidly with high recoveries and good selectivity despite extremely simple sample preparation. 相似文献
82.
The efficiencies in derivatization of reducing carbohydrates were compared by capillary electrophoresis using maltose as a model with nine monoaminobenzene derivatives by reductive amination in the presence of sodium cyanoborohydride. We found that aminobenzene derivatives substituted at the 3-position showed good reactivity with reducing carbohydrates as expected from the reaction mechanism, although the fluorescence intensities and molar absorptivities of these derivatives were not as high as those of 2- and 4-aminobenzene derivatives. The reagents, 3-aminobenzamide and 3-aminobenzoic acid, which showed the highest reactivity, were applied to the labeling of carbohydrate chains obtained from some sialic acid-containing glycoprotein samples, and also high-mannose and hybrid-type oligosaccharides. Capillary electrophoresis of these labeled carbohydrate chains in an inner surface-modified capillary with (50% phenyl)methylpolysiloxane allowed excellent separation of sialic acid-containing carbohydrate chains derived from fetuin and thyroglobulin as well as high mannose-type and hybrid-type carbohydrates derived from bovine pancreas ribonuclease B, soybean agglutinin and hen ovalbumin. The lower limit of calibration was as low as the 10(-16) mol (injected amount) with helium-cadmium laser induced detection. 相似文献
83.
Aoyama C Santa T Tsunoda M Fukushima T Kitada C Imai K 《Biomedical chromatography : BMC》2004,18(9):630-636
A fully automated amino acid analyzer using NBD-F (4- fluoro-7-nitro-2,1,3-benzoxadiazole) as a fluorescent derivatization reagent was developed. The whole analytical process was fully automated from derivatization, injection to HPLC separation and quantitation. The derivatization reaction conditions were re-evaluated and optimized. Amino acids were derivatized by NBD-F for 40 min at room temperature in the borate buffer (pH 9.5). The derivatives were separated within 100 min and fluorometrically detected at 540 nm with excitation at 470 nm. The detection limits for amino acids were in the range of 2.8-20 fmol. The calibration curves were linear over the range of 20 fmol to 20 pmol on column with the correlation coefficients of 0.999. The coefficients of variation were less than 5% at 3 pmol injection for all amino acids. Amino acids in rat plasma were determined by the proposed HPLC method. 相似文献
84.
Summary A weighing tube has been designed for volatile liquids in carbon-hydrogen and nitrogen microdetermination. The tube of transparent quartz, in which a piece of platinum wire is inserted, is used without potassium chlorate, and the procedure of sample-taking can be markedly simplified.
Zusammenfassung Ein Wägeröhrchen für die Mikrobestimmung von Kohlenstoff, Wasserstoff und Stickstoff in flüchtigen Flüssigkeiten wurde beschrieben. Es besteht aus durchsichtigem Quarz und enthält ein Stückchen Platindraht. Es wird ohne Kaliumchlorat verwendet. Die Probenahme ist erheblich vereinfacht.
Résumé Les auteurs ont conçu un tube permettant de prélever de peser et les liquides volatils pour le microdosage du carbone de l'hydrogène et de l'azote. Le tube est en quartz transparent dans lequel est serti un fil de platine; il peut être utilisé sans chlorate de potassium et permet de simplifier d'une façon sensible l'opération de prélèvement de l'échantillon.相似文献
85.
Tadayosi Kitada 《Journal of polymer science. Part A, Polymer chemistry》2001,39(13):2315-2325
New poly(N‐isopropylacrylamide) gels were prepared under high pressure (ca. 200 MPa) during gelation. The preparation‐pressure dependence of the deswelling speed of the gels was measured with a conventional T‐jump method. The deswelling time of a gel rod 2.2 mm in diameter prepared at 193 MPa was about 200 s, 1000 times faster than that of a homogeneous poly(N‐isopropylacrylamide) gel. Moreover, the collective diffusion coefficient, the thermal fluctuation, and the ensemble‐average intensity of the swollen gel networks were obtained with dynamic light scattering measurements. Both the enthalpy and entropy of the gels were estimated from equilibrium swelling curves with the Flory–Huggins interaction parameter evaluated with mean field theory based on the Flory‐type of the Gibbs free‐energy formula. It was found that the networks of the gels had an inhomogeneous structure newly introduced by the preparation pressure. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2315–2325, 2001 相似文献
86.
One class of universal mechanisms that generate power-law probability distributions is that of random multiplicative processes. In this paper, we consider a multiplicative Langevin equation driven by non-Gaussian colored multipliers. We analytically derive a formula that relates the power-law exponent to the statistics of the multipliers and numerically confirm its validity using multiplicative noise generated by chaotic dynamical systems and by a two-valued Markov process. We also investigate the relationship between our treatment and the large deviation analysis of time series, and demonstrate the appearance of log-periodic fluctuations superimposed on the power-law distribution due to the non-Gaussian nature of the multipliers. 相似文献
87.
Toshiyuki Kitada 《Monatshefte für Mathematik》1990,110(3-4):283-295
LetG be a locally compact Vilenkin group. We give a maximal function characterization of the weightedH
p
spaces overG, and give a Hörmander type multiplier theorem for these spaces. 相似文献
88.
89.
90.
35Cl NQR and XRD have been investigated on the solid solution Cs2[Ag(I) x Au(I)1???x Cl2][Au(III)Cl4] which yielded NQR lines by annealing. The crystal forms a tetragonal cell in the whole range of x. However, a change of the modification occurs at x?≈?0.85. The increase of c and decrease of a were observed in the range of 0.0?≤?x?≤?0.7. 相似文献