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Search Results: 1 - 10 of 228954 matches for " Janhavi R Rao* "
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Reaearch: SIMULTANEOUS HPTLC ANALYSIS OF ATENOLOL AND INDAPAMIDE IN TABLETS
Savita S Yadav,Janhavi R Rao*
Pharmacie Globale : International Journal of Comprehensive Pharmacy , 2011,
Abstract: A simple, fast, precise, selective and accurate HPTLC method was developed and validated for the simultaneous determination of atenolol and indapamide from bulk and formulations. Chromatographic separation was achieved on aluminum foil plates precoated with silica gel 60F254, with toluene: ethyl acetate: methanol: ammonia 5:3:3:0.1 (v/v) as mobile phase. Detection was performed densitometrically at 229 nm. The RF of atenolol and indapamide were 0.27 and 0.71, respectively. Linearity was observed in the concentration range of 200-1200 ng/spot for atenolol and 100-600 ng/spot for indapamide. Percent recoveries obtained for both the drugs were 99.95 ± 0.18% and 99.67 ± 0.80%, respectively. The method was validated according to the ICH guidelines with respect to specificity, linearity, accuracy, precision and robustness. The method developed can be used for the routine analysis of atenolol and indapamide from their combined dosage form.
Research: SIMULTANEOUS DETERMINATION OF PARACETAMOL AND LORNOXICAM BY RP-HPLC IN BULK AND TABLET FORMULATION
Anuradha S Jagtap,Savita S Yadav,Janhavi R Rao*
Pharmacie Globale : International Journal of Comprehensive Pharmacy , 2011,
Abstract: A simple, specific, accurate and precise reverse phase high pressure liquid chromatographic method has been developed for the simultaneous determination of paracetamol and lornoxicam from tablets by reverse phase C18 column ODS HyperSil (250 mm, 4.6 mm, 5 μm). The sample was analyzed using methanol: water (85:15, v/v), as a mobile phase at a flow rate of 1 mL/min. and detection at 259 nm. The retention time for paracetamol and lornoxicam was found to be 3.30 min and 2.14 min, respectively. The method can be used for estimation of combination of these drugs in tablets. The method was validated as per ICH guidelines. The linearity of developed method was achieved in the range of 0.4-1.4 μg/mL for paracetamol and 0.6-1.6 μg/ mL for lornoxicam and recoveries from tablets were between 100.36% and 100.17%. Due to these attributes, the proposed method could be used for routine quality control analysis of these drugs in combined dosage forms.
Electron Paramagnetic Resonance Study of Phase Segregation in Nd$_{0.5}$Sr$_{0.5}$MnO$_3$
Janhavi P. Joshi,A. K. Sood,S. V. Bhat,A. R. Raju,C. N. R. Rao
Physics , 2002,
Abstract: We present results of an electron paramagnetic resonance (EPR) study of Nd$_{1-x}$Sr$_x$MnO$_3$ with x = 0.5 across the paramagnetic to ferromagnetic, insulator to metal transition at 260 K (T$_c$) and the antiferromagnetic, charge ordering transition (T$_N$ = T$_{co}$) at 150 K. The results are compared with those on Nd$_{0.45}$Sr$_{0.55}$MnO$_3$ which undergoes a transition to a homogeneous A-type antiferromagnetic phase at T$_N$ = 230 K and on La$_{0.77}$Ca$_{0.23}$MnO$_3$ which undergoes a transition to coexisting ferromagnetic metallic and ferromagnetic insulating phases. For x = 0.5, the EPR signals below T$_c$ consist of two Lorentzian components attributable to the coexistence of two phases. From the analysis of the temperature dependence of the resonant fields and intensities, we conclude that in the mixed phase ferromagnetic and A-type antiferromagnetic (AFM) phases coexist. The x = 0.55 compound shows a single Lorentzian throughout the temperature range. The signal persists for a few degrees below T_N. The behaviour of the A-type AFM phase is contrasted with that of the two ferromagnetic phases present in La$_{0.77}$Ca$_{0.23}$MnO$_3$. The comparison of behaviour of A-type AFM signal observed in both Nd$_{0.5}$Sr$_{0.5}$MnO$_3$and Nd$_{0.45}$Sr$_{0.55}$MnO$_3with the two FM phases of La$_{0.77}$Ca$_{0.23}$MnO$_3$, vis-a-vis the shift of resonances with respect to the paramagnetic phases and the behaviour of EPR intensity as a function of temperature conclusively prove that the Nd$_{0.5}$Sr$_{0.5}$MnO$_3$undergoes phase separation into A-type AFM and FM phases.
Research: DEVELOPMENT AND VALIDATION OF HPLC METHOD FOR SIMULTANEOUS QUANTITATION OF PARACETAMOL AND DEXKETOPROFEN TROMETAMOL IN BULK DRUG AND FORMULATION
Toufik S Mulla,Janhavi R Rao*,Savita S Yadav,Vishal V Bharekar
Pharmacie Globale : International Journal of Comprehensive Pharmacy , 2011,
Abstract: An accurate, simple, sensitive and precise reverse phase high performance liquid chromatographic (RP-HPLC)method for the determination of paracetamol and dexketoprofen trometamol was developed and validated in the bulk drug and in tablet dosage form. Thermo Hypersil ODS–C18 (250 mm × 4.6 mm, 5.0 μ) used as stationary phase and methanol: ammonium acetate buffer (65: 35 v/v) as mobile phase at a flow rate of 1.0 ml/min and the detection wavelength was 256 nm. The retention time for paracetamol and dexketoprofen trometamol was found to be 3.20 and 5.94 min, respectively. Proposed method was validated for precision, accuracy, linearity range androbustness.
An electron paramagnetic resonance study of Pr_{0.6}Ca_{0.4}MnO_{3} across the charge ordering transition
Rajeev Gupta,Janhavi P. Joshi,S. V. Bhat,A. K. Sood,C. N. R. Rao
Physics , 2000, DOI: 10.1088/0953-8984/12/30/319
Abstract: We report the first electron paramagnetic resonance studies of single crystals and powders of Pr_{0.6}Ca_{0.4}MnO_{3} in the 300-4.2 K range, covering the charge ordering transition at ~ 240 K and antiferromagnetic transition (T_N) at ~ 170 K. The asymmetry parameter for the Dysonian single crystal spectra shows anomalous increase at T_{co}. Below T_{co} the g-value increases continuously, suggesting a gradual strengthening of orbital ordering. The linewidth undergoes a sudden increase at T_{co} and continues to increase down to T_N. The intensity increases as the temperature is decreased till T_{co} due to the renormalization of magnetic susceptibility arising from the build up of ferromagnetic correlations. The value of the exchange constant, J, is estimated to be 154 K.
An Electron Paramagnetic Resonance Study of Electron-Hole Asymmetry in Charge Ordered Pr_1-x Ca_xMnO_3 (x=0.64, 0.36)
Janhavi P. Joshi,A. K. Sood,S. V. Bhat,K. Vijaya Sarathy,C. N. R. Rao
Physics , 2002,
Abstract: We present and compare the results of temperature-dependent electron paramagnetic resonance (EPR) studies on Pr_1-x Ca_xMnO_3 for x = 0.64 which is electron-doped with those on the hole doped x = 0.36 composition. The temperature dependence of the various parameters obtained from the powder and single crystal spectra show significant differences between the two manganites. At room temperature the `g' parameter for the electron doped system is less than the free electron `g' value `g_e', whereas for the hole-doped system it is more than `g_e'. Further, the `g' value and the linewidth obtained from the powder spectra as well as the single crystal spectra show different functional dependences on temperature in the two systems. Quite strikingly, the peak observed at T_{co} in the temperature dependence of the asymmetry parameter, alpha, of the single crystal spectra in the hole-doped system is absent in the electron-doped system. We understand this contrasting behaviour of the EPR parameters in the two systems in terms of very different nature of microscopic interactions in them.
Temperature-dependent electron paramagnetic resonance studies of charge ordered Nd_0.5Ca_0.5MnO_3
Janhavi P. Joshi,Rajeev Gupta,A. K. Sood,S. V. Bhat,A. R. Raju,C. N. R. Rao
Physics , 2000,
Abstract: We report Electron Paramagnetic Resonance measurements on single crystalline and powder samples of Nd_0.5Ca_0.5MnO_3 across the charge-ordering transition at T_co=240 K down to the antiferromagnetic ordering transition at T_N = 140 K. The changes in the linewidth, g-factor and intensity as functions of temperature are studied to understand the nature of spin-dynamics in the system. We explain the observed large decrease in the linewidth from T_N to T_co in terms of motional narrowing caused by the hopping of the Jahn-Teller polarons yielding an activation energy of E_a = 0.13 eV. Similar analysis of data on Pr_0.6Ca_0.4MnO_3 published earlier gives E_a=0.2 eV. Below T_co, the g-value increases continuously suggesting a gradual strengthening of the orbital ordering. We give a qualitative explanation of the temperature dependence and of the maximum in the asymmetry ratio A/B observed at T_co in single crystal spectra which also supports the themodel of motional narrowing.
Research: VALIDATED HPTLC METHOD FOR SIMULTANEOUS QUANTITATION OF CEFIXIME AND OFLOXACIN IN BULK DRUG AND IN PHARMACEUTICAL FORMULATION
Janhavi Rao*,Kamini Sethy,Savita Yadav
Pharmacie Globale : International Journal of Comprehensive Pharmacy , 2011,
Abstract: This work is concerned with the simultaneous determination of cefixime and ofloxacin in a bulk drug and pharmaceutical formulations by high performance thin layer chromatographic (HPTLC) method. Chromatographic separation was achieved on aluminum foil plates precoated with silica gel 60GF-254, with n-butanol: ammonia: water: DMSO (8:3:1:2, v/v/v/v) as mobile phase. Detection was performed densitometrically at 297 nm. The RF of cefixime and ofloxacin were 0.55 and 0.65, respectively. The reliability of the method was assessed by evaluation of linearity (30-180 ng/spot for both cefixime and ofloxacin respectively. Accuracy (99.82 % for cefixime and 99.84 % for ofloxacin), and specificity, in accordance with ICH guidelines. The method is simple, accurate, and rapid and can therefore be used for routine analysis of both drugs in quality control laboratories.
A stability-indicating high performance liquid chromatographic method for the determination of diacerein in capsules
Rao Janhavi,Chauhan Kanchan,Mahadik K,Kadam S
Indian Journal of Pharmaceutical Sciences , 2009,
Abstract: A stability-indicating HPLC method was developed and validated for the quantitative determination of diacerein in capsule dosage forms. An isocratic separation was achieved using a perfectsil target ODS-3, 250x4.6 mm i.d., 5 μm particle size columns with a flow rate of 1 ml/min and using a UV detector to monitor the eluate at 254 nm. The mobile phase consisted of phosphate buffer:acetonitrile (40:60, v/v) with pH 4.0 adjusted with phosphoric acid. The drug was subjected to oxidation, hydrolysis, photolysis and thermal degradation. Diacerein was found to degrade in acidic, basic, and oxidative stress and also under neutral condition. Complete separation of degraded products was achieved from the parent compound. All degradation products in an overall analytical run time of approximately 10 min with the parent compound diacerein eluting at approximately 4.9 min. The method was linear over the concentration range of 1-10 μg/ml (r2 = 0.9996) with a limit of detection and quantitation of 0.01 and 0.05 μg/ml respectively. The method has the requisite accuracy, selectivity, sensitivity, precision and robustness to assay diacerein in capsules. Degradation products resulting from the stress studies did not interfere with the detection of diacerein and the assay is thus stability-indicating.
Study of Selectivity and Permeation In Voltage-Gated Ion Channels
Janhavi Giri
Physics , 2012,
Abstract: Ion channels are membrane proteins responsible for an enormous range of biological functions. Ion selectivity and permeation are based on simple laws of physics and chemistry. Ion channels are therefore ideal candidates for physical investigation. A reduced model generates the selectivity of voltage-gated L-type calcium channel under a wide range of ionic conditions using only two parameters with unchanging values. The reasons behind the success of this reduced model are investigated. Monte Carlo simulations are performed investigating the role of flexibility of the side chains in the selectivity of calcium channels under a wide range of ionic conditions. Results suggest that the exact location and mobility of oxygen ions have little effect on the selectivity behavior of calcium channels. The first order determinant of selectivity in calcium channels is the density of charge in the selectivity filter. Flexibility seems a second order determinant. Single channel planar lipid bilayer experiments are performed to determine the selectivity, permeation, and sialic acid specificity of a bacterial outer-membrane channel NanC of Ecoli. NanC exhibits a large unit conductance varying with the applied voltage polarity, anion selectivity, and voltage gating. Unitary conductance of NanC decreases significantly in presence of the buffer HEPES. Alternate buffers are tested. Results suggest that the sialic acid specificity of NanC should be performed in low concentration salt solutions without pH buffers adjusted to neutral pH 7.0. Neu5Ac changes the gating and considerably increases the ionic conductance of NanC. The effect of Neu5Ac on the unitary current through NanC saturates at higher Neu5Ac concentrations. Interestingly, Neu5Ac reduces the ionic conductance of OmpF: frequent, long closures are seen. Thus, in E.coli sialic acid translocation is specifically facilitated by NanC, and not by OmpF.
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