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排序方式: 共有248条查询结果,搜索用时 15 毫秒
31.
《Analytical letters》2012,45(1):80-89
Abstract Three simple, sensitive, and highly accurate spectrophotometric methods have been developed for the determination of oxomemazine hydrochloride (OXO‐HCl) in bulk and in pharmaceutical formulations. These methods are based on the formation of yellow ion‐pair complexes between the examined drug and bromocresol green (BCG), congo red (CR), and methyl orange (MO) as reagents in universal buffer solution of pH 3.0, 5.5, and 3.5, respectively. The formed complexes were extracted with chloroform and measured at 413, 495, and 484 nm, respectively for the three systems. The best conditions of the reaction were studied and optimized. Beer's law was obeyed in the concentration ranges 2.0–18.0, 2.0–14.0, and 2.0–16.0 µg ml?1 with molar absorptivity of 4.1×104, 1.1×104, and 3.5×104 mol?1cm?1, for the BCG, CR, and MO methods, respectively. Sandell's sensitivity, correlation coefficient, detection, and quantification limits are also calculated. The proposed methods have been applied successfully for the analysis of the drug in pure and in its dosage forms. No interference was observed from common pharmaceutical excipients and additives. Statistical comparison of the results with those obtained by HPLC method shows excellent agreement and indicates no significant difference in accuracy and precision. 相似文献
32.
33.
Neha Munot Ujjwala Kandekar Chaitali Rikame Abhinandan Patil Poulomi Sengupta Shabana Urooj Anusha Bilal 《Molecules (Basel, Switzerland)》2022,27(20)
Thiolation of polymers is one of the most appropriate approaches to impart higher mechanical strength and mucoadhesion. Thiol modification of gum karaya and gum acacia was carried out by esterification with 80% thioglycolic acid. FTIR, DSC and XRD confirmed the completion of thiolation reaction. Anticancer potential of developed thiomer was studied on cervical cancer cell lines (HeLa) and more than 60% of human cervical cell lines (HeLa) were inhibited at concentration of 5 µg/100 µL. Immobilized thiol groups were found to be 0.8511 mmol/g as determined by Ellman’s method. Cytotoxicity studies on L929 fibroblast cell lines indicated thiomers were biocompatible. Bilayered tablets were prepared using Ivabradine hydrochloride as the model drug and synthesized thiolated gums as mucoadhesive polymer. Tablets prepared using thiolated polymers in combination showed more swelling, mucoadhesion and residence time as compared to unmodified gums. Thiol modification controlled the release of the drug for 24 h and enhanced permeation of the drug up to 3 fold through porcine buccal mucosa as compared to tablets with unmodified gums. Thiolated polymer showed increased mucoadhesion and permeation, anticancer potential, controlled release and thus can be utilized as a novel excipient in formulation development. 相似文献
34.
Tadalafil( TAD)and dapoxetine HCl( DAP)are recently co-formulated and both show native fluo-rescence. Therefore,a novel,accurate,specific and sensitive reversed-phase high performance liquid chroma-tographic method with fluorescence detection was developed and validated for their separation and quantitation in dosage form and human plasma using avanafil as an internal standard( IS). Separation was achieved using isocratic elution within 7. 0 min on C18 column and acetonitrile-0. 15% triethylamine( 40∶60,v/v;pH 4)as a mobile phase. The flow rate was 1. 0 mL/min and the detection was time-programmed at 330,410 and 370 nm for TAD,DAP and IS,respectively,after excitation at 236 nm. The linear ranges from 0. 01 to 30. 00 μg/mL for each drug with the limits of detection of 4. 20 and 7. 20 ng/mL for TAD and DAP,respectively. The method was validated in accordance to the International Conference on Harmonization( ICH)guidelines and was successful-ly applied to spiked human plasma with mean recoveries of 98. 17% and 98. 83% for TAD and DAP respectively. 相似文献
35.
N. A. Talzhanov V. A. Raldugin M. M. Shakirov G. A. Atazhanova S. M. Adekenov 《Chemistry of Natural Compounds》2005,41(4):420-422
Dehydroisoleucomisin (anhydroaustricin) was converted in good yield to guai-1(10),3,5,7(11), 8-pentaen-2-on-12,8-olide by
the action of anhydrous HCl in dry DMF. The chemical structure of the product was established using spectral data. The probable
formation scheme of this lactone was proposed to include a series of prototopic transformations and ionic dehydrogenation
of intermediates.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 339–340, July–August, 2005. 相似文献
36.
For bimolecular surface reactions, temperature programmed desorption (TPD) cannot be used efficiently to detect the product if either of the reactants desorbs before the product. A modification of TPD (differential-conversion TPD, or DCTPD) that circumvents this problem is described in this paper. The reactant desorbing at high temperature is first adsorbed as in normal TPD. The surface is then exposed to a continuous flux of the other reactant, and the rate of product desorption is monitored at the same time. The flux is kept so low that the coverage of the reactant first adsorbed scarcely changes. The rate constant is then determined using this measured coverage and that calculated for the impinging species from its previously-determined adsorption/desorption kinetics. A formalism is also developed for cases in which a continuum of related pathways with a distribution of activation energies is present. Experimental application of DCTPD is demonstrated in the particular case of HCl production from SiH4 and TiCl4 on TiSi2. 相似文献
37.
Koji Ishida Tomoshige Morita Takeshi Hamada 《Fresenius' Journal of Analytical Chemistry》1981,305(4):257-261
Summary The thin-layer chromatographic behaviour of the noble metals on ECTEOLA-cellulose has been examined in HCl and aqueous chloride solutions of Li, Na, Mg, Ca, Sr and Al. The Rf-values decrease in the order Ir(III) Rh(III) > Ru(III) > Pd(II) > Pt(IV) > Ir(IV) > Au(III) in all of the media of higher chloride concentrations (3M to 5M), in which there are sufficiently large differences in Rf-values of adjacent metals to resolve them clearly. Especially, the HCl solutions with or without H2O2 are very suitable for multi-component separations of the noble metals.
DC-Trennung von Edelmetallen auf ECTEOLA-Cellulose in salzsauren und wäßrigen Chloridlösungen
Zusammenfassung Das Verhalten von Edelmetallen wurde in salzsauren Lösungen sowie in Lösungen der Chloride von Li, Na, Mg, Ca, Sr und Al geprüft. Die Rf-Werte nehmen in allen Medien mit höherer Chlorid-konzentration (3M bis 5M) in folgender Reihenfolge ab: Ir(III) Rh(III) > Ru(III) > Pd(II) > Pt(IV) > Ir(IV) > Au(III). Die Unterschiede in den Rf-Werten sind groß genug, um eine deutliche Trennung zu gewährleisten. Salzsaure Lösungen mit oder ohne H2O2-Zusatz sind besonders gut für die Trennung von Vielkomponenten-Gemischen geeignet.相似文献
38.
Summary This paper the possibility of determining small quantities of HCl by derivatization with 7-oxabicyclo-(4.1.0)-heptane and
subsequent gas chromatographic identification of the reaction product 2-chlorocyclohexanol is examined. The detection limit
for the derivative (2-chlorocyclohexanol) is equivalent to 2 pg HCl. On account of various problems, discussed in the paper,
this detection limit is not achieved in practice. It is nevertheless apparent that concentrations of HCl in the ppm-region
(quantities of HCl<1 μg) can be determined without difficulty. The scope for this method of analysis is disscussed.
Nachweis von geringen Mengen HCl durch Reaktion von 7-Oxabicyclo-(4.1.0)-heptan mit HCl
Zusammenfassung In der vorliegenden Arbeit wird die M?glichkeit untersucht, kleine Mengen HCl durch derivatisierung mit 7-Oxabicyclo-(4.1.0)-heptan und anschlie?endem gas-chromatographischen Nachweis des Reaktionsproduktes 2-Chlorcyclohexanol zu bestimmen. Die Nachweisgrenze für das Produkt der Derivatisierung (2-Chlorcyclohexanol) entspricht 2 pg HCl. Durch verschiedene Probleme, die im Rahmen dieser Arbeit diskutiert werden, wird diese Nachweisgrenze in der Praxis nicht erreicht. Es zeigt sich jedoch, da? HCl-Konzentrationen im Bereich von ppm (bzw. HCl-Mengen<1 μg) ohne weiteres zu bestimmen sind. Die M?glichkeiten dieser Analysenmethode werden diskutiert.相似文献
39.
J. J. Fritz 《Journal of solution chemistry》1984,13(5):369-382
Experimental heats of solution of CuCl in aqueous HCl-HClO4 mixtures have been analyzed using a virial model to represent the effects of solution composition on activity coefficients of all species. The thermodynamics needed for this purpose are described briefly. Optimization of the representation of the data produced values of standard heats of solution to form CuCl
2
–
and CuCl
3
2–
which agreed with these previously deduced from solubility data, as well as temperature derivatives of the virial parameters. Uses of the resultant information are discussed. 相似文献
40.