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101.
G. Saravanan M. V. Suryanarayana N. Balaji N. Someswararao N. M. Sekhar 《Chromatographia》2008,67(1-2):179-182
This paper describes the development of a stability-indicating high-performance liquid chromatographic (HPLC) method for quantitative
determination of topotecan hydrochloride, a semi-synthetic derivative of camptothecin and anti-tumor drug with topoisomerase
I-inhibitory activity. Chromatographic separation was achieved on a C18 column with a mixture of phosphate buffer and acetonitrile as mobile phase. The method was validated for linearity, accuracy,
precision, and robustness. Forced degradation studies were performed by treating bulk samples of topotecan hydrochloride with
acid (0.5 M hydrochloric acid), base (0.5 M sodium hydroxide), oxidizing agent (10% v/v hydrogen peroxide), heat (60 °C), and UV light (254 nm). 相似文献
102.
Bindu KH Reddy IU Anjaneyulu Y Suryanarayana MV 《Journal of chromatographic science》2012,50(4):368-372
A simple, linear gradient, rapid, precise and stability-indicating analytical method was developed for the estimation of related substances and degradants of paliperidone API and tablets. The chromatographic separations were achieved using an Acquity ultra-performance liquid chromatograph (BEH 100 mm, 2.1 mm, 1.7 μm C-18 column) employing 0.01 M potassium dihydrogen phosphate buffer (pH 2.0) as mobile phase A and acetonitrile-water (9:1) as mobile phase B. A linear gradient (mobile phase A, mobile phase B in the ratio of 84:16) with a 0.45 mL/min flow rate was chosen. All six impurities were eluted within five minutes of run time. The column temperature was maintained at 25 °C and a detector wavelength of 238 nm was employed. Paliperidone was exposed to thermal, photolytic, hydrolytic and oxidative stress conditions. The stressed samples were analyzed by the proposed method. Considerable degradation of the analyte was observed when it was subjected to oxidative conditions and impurity F was found to be the major degradant. Peak homogeneity data of paliperidone obtained by photodiode array (PDA) detection demonstrated the specificity of the method in the presence of degradants. The method was validated with respect to linearity, precision, accuracy, ruggedness, robustness, limit of detection and limit of quantification. 相似文献
103.
Reddy DC Bapuji AT Rao VS Himabindu V Ravinder S 《Journal of chromatographic science》2012,50(6):538-546
A rapid and high sensitive liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was developed and validated for the quantification of zolpidem in human EDTA plasma using ondansetron (IS) as an internal standard. The analyte and IS were extracted from human plasma using ethyl acetate and separated on a C18 column (Inertsil-ODS, 5 μm, 4.6 × 50 mm) interfaced with a triple quadrupole tandem mass spectrometer. The mobile phase, which consisted of a mixture of methanol and 20 mM ammonium formate (pH 5.00 ± 0.05; 75:25 v/v), was injected at a flow rate of 0.40 mL/min. The retention times of zolpidem and IS were approximately 1.76 and 1.22. The LC run time was 3 min. The electrospray ionization source was operated in positive ion mode. Multiple reaction monitoring used the [M + H](+) ions m/z 308.13 → 235.21 for zolpidem and m/z 294.02 → 170.09 for the ondansetron, respectively. Five freeze-thaw cycles was established at -20 and -70°C.The linearity of the response/concentration curve was established in human EDTA plasma over the concentration range 0.10-149.83 ng/mL. The lower detection limit [(signal-to-noise (S/N) > 3] was 0.04 ng/mL and the lower limit of quantification (S/N > 10) was 0.10 ng/mL. This LC-MS-MS method was validated with intra-batch and inter-batch precision of 0.52-8.66.The intra-batch and inter-batch accuracy was 96.66-106.11. Recovery of zolpidem in human plasma was 87.00% and IS recovery was 81.60%. The primary pharmacokinetic parameters were T(max) (h) = (1.25 ± 0.725), C(max) (ng/mL) (127.80 ± 34.081), AUC(0→t), = (665.37 ± 320.982) and AUC(0→∞), 686.03 ± 342.952, respectively. 相似文献
104.
A.?Keane T.?Dahms J.?Lehnert S.A.?Suryanarayana P.?H?vel E.?Sch?llEmail author 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(12):407
We use a generic model for type-I excitability (known as the SNIPER or SNIC model) to describe the local dynamics of nodes within a network in the presence of non-zero coupling delays. Utilising the method of the Master Stability Function, we investigate the stability of the zero-lag synchronised dynamics of the network nodes and its dependence on the two coupling parameters, namely the coupling strength and delay time. Unlike in the FitzHugh-Nagumo model (a model for type-II excitability), there are parameter ranges where the stability of synchronisation depends on the coupling strength and delay time. One important implication of these results is that there exist complex networks for which the adding of inhibitory links in a small-world fashion may not only lead to a loss of stable synchronisation, but may also restabilise synchronisation or introduce multiple transitions between synchronisation and desynchronisation. To underline the scope of our results, we show using the Stuart-Landau model that such multiple transitions do not only occur in excitable systems, but also in oscillatory ones. 相似文献
105.
Vikas Dubey Jagjeet Kaur N. S. Suryanarayana K. V. R. Murthy 《Research on Chemical Intermediates》2014,40(2):531-536
This paper reports TL glow curve analysis and evaluation of kinetic parameter for Amarnath stone collected from Amarnath Holy Cave. TL was recorded with different heating rates (3.3, 4, 6.7, 8, and 10 ° s?1). The samples gave good TL peaks at 310, 314, 308, 323, and 327 °C for the different heating rates. The corresponding activation energy (E) values were calculated. The peaks were indicative of second-order kinetics. Samples were characterized by XRD analysis. Inductively coupled plasma activated emission spectroscopic (ICP–AES) analysis was performed to determine percentages of elements in the natural mineral. Results from ICP–AES and XRF (X-ray fluorescence spectroscopy) studies were compared. 相似文献
106.
Jagjeet Kaur Deepti Singh Vikas Dubey N. S. Suryanarayana Yogita Parganiha Pooja Jha 《Research on Chemical Intermediates》2014,40(8):2737-2771
In this review different methods of preparing lanthanum aluminate (LaAlO3) phosphors are discussed. The molten salt method, the combustion method, the sucrose method, and the coprecipitation technique are the best methods for preparing LaAlO3 phosphors with small particle size and high surface area by low-temperature synthesis. LaAlO3 usually has a rhombohedral structure. It has good dielectric properties and, hence, is regarded as an attractive alternative to SiO2 in microelectronic devices. LaAlO3 phosphors have excellent chemical and thermal stability, mechanical durability, and exploitable optical and electronic properties, leading to a wide range of potential applications. LaAlO3 phosphors doped with rare-earth ions have luminescence properties and can, hence, be used in optical display systems. 相似文献
107.
A rapid, efficient, economical, and easy-to-scale method for the effective conversion of carbamates to corresponding N,N-dichlorocarbamates by using sodium hypochlorite in acidic medium has been described. N,N-Dichlorocarbamates were obtained in quantitative yield through a simple workup in reduced reaction time.
108.
Vikas Dubey Jagjeet Kaur N. S. Suryanarayana K. V. R. Murthy 《Research on Chemical Intermediates》2013,39(8):3689-3697
This paper reports the thermoluminescence (TL) and chemical characterization of natural calcite collected from Kodwa mines of the C.G. Basin. The sample was irradiated with a 10-Gy dose from an Sr-90 beta source. The heating rate used for TL measurements was 6.7 °/s. The sample had a good TL peak at approximately 127 °C and the corresponding kinetic parameter were calculated. The effect of annealing temperature is also described for natural calcite. The photoluminescence excitation spectrum at ~254 nm and the corresponding emission spectrum peak at 395 nm are reported. Inductively coupled plasma–activated emission spectroscopy (ICP–AES) was conducted to determine the percentages of elements in the calcite mineral. 相似文献
109.
B. Gopala Krishna Ravichandra Gundakaram S. V. Suryanarayana R. D. K. Misra 《Physica C: Superconductivity and its Applications》1992,200(3-4):425-433
Samples with the nominal composition Bi2Sr2Ca1−xNaxCu2Oy (if with X = 0.05, 0.2, 0.4 and 0.5) were prepared by the solid state reaction method. The role of Na and the effect of various heat treatments in the 2212 composition were studied. From the X-ray diffraction data it is found that the samples annealed for longer duration have shown a single phase 2212. From the DC four-probe resistivity data, it was found that the Tc (zero) varies from 79 to 89 K. It is believed that doping with an alkali element would reduce the oxygen content due to monovalency and gives an effect similar to that during heat treatment under low oxygen pressure or quenching. The presence of sodium in the samples was confirmed by electron probe microanalysis. 相似文献
110.
H. Naik V.T. Nimje D. Raj S.V. Suryanarayana A. Goswami Sarbjit Singh S.N. Acharya K.C. Mittal S. Ganesan P. Chandrachoodan V.K. Manchanda V. Venugopal S. Banarjee 《Nuclear Physics A》2011
The yields of various fission products in the 10 MeV bremsstrahlung-induced fission of 232Th, 238U and 240Pu were determined using a recoil catcher and off-line γ-ray spectrometric techniques. From the yield data, mass yield distributions were obtained using charge distribution corrections. The higher yields of fission products around mass numbers 133–135, 138–140, 143–145 and their complementary products in the neutron and bremsstrahlung-induced fission of 232Th, 238U and 240Pu were interpreted based on nuclear structure effects. From the mass yield distribution, the peak-to-valley (P/V) ratio was also obtained for the above fissioning systems. The present data, along with data from the literature on different bremsstrahlung- and mono-energetic neutron-induced fissions of 232Th and 238U are interpreted to examine the influence of excitation energy on the peak to valley ratio. For the same compound nucleus 240Pu?, the data in the 10–30 MeV bremsstrahlung-induced fission of 240Pu were compared with similar data of thermal to 14 MeV neutron-induced fission of 239Pu and the spontaneous fission of 240Pu to examine the role of excitation energy due to bremsstrahlung radiation and mono-energetic neutrons. 相似文献