RP-HPLC method development using analytical QbD approach for estimation of cyanidin-3-O-glucoside in natural biopolymer based microcapsules and tablet dosage form

Deepika Thakur,Ashay Jain,Gargi Ghoshal,U. S. Shivhare,O. P. Katare 한국약제학회 2017 Journal of Pharmaceutical Investigation Vol.47 No.5

Anthocyanin has been proven to impart several health benefits and biological functions. Though, various analytical methods have been reported for single/multicomponent analysis of anthocyanins, found to be tedious, time consuming and difficult to reproduce. Analytical studies on specific anthocyanins for estimation using an approach of Analytical Quality by Design are scarce. USP method is only reliable for cyanidin-3-O-glucoside (CY-3- O-Glu) estimation, but exploring many disadvantage of having high buffer concentration in mobile phase system and gradient elution, hence column blockage. So there is need to develop a novel HPLC method to overcome this problem with the use organic solvents with lesser volume of buffer in isocratic mode of elution. The aim is to develop a robust and precise method for estimation of CY-3-O-Glu in biopolymer based microcapsules and tablets. The optimized method consisted of mobile phase containing solvent A and B, flow rate 0.8 mL/min with 20 min of analysis time. The method was further validated in accordance with current ICH guidelines Q2 (R1) and found to be highly selective for component in the presence of degradation products confirmed by Mass spectra. Therefore, the proposed method was found to be suitable for routine analysis of CY-3-O-Glu in food and pharmaceutical based formulations.

Dielectric and impedance spectroscopic behaviour of alkali oxide - containing glass ceramics in the system [SrO.TiO2]-[SiO2.B2O3]

O.P. Thakur,Lakshman Pandey,Devendra Kumar,Om Parkash 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.2

Dielectric properties are strongly dependent on crystallization conditions, which determined the amount of SrTiO3 and secondary crystalline phases and the microstructure of the glass ceramics. Earlier reports confirm that the crystallization of the SrTiO3 phase in borosilicate (without an alkali oxide additive) as well as in aluminosilicate glassy matrix is found to be complex and difficult. Glass ceramics with varying amounts of alkali oxide (K2O) have been prepared in the strontium titanate borosilicate glass system. The glasses were crystallized in the temperature range 1073-1325 K. It is observed that the pure strontium titanate (SrTiO3) phase can be crystallized at higher temperature by choosing an optimum amount of alkali oxide (K2O). Dielectric characteristics of glass ceramic samples were measured with respect to frequency (0.1 kHz to 1 MHz) and temperature (300 to 500 K). The value of the dielectric constant is higher when Sr2B2O5 crystallizes as a primary phase while it decreases significantly when SrTiO3 crystallizes as a major crystalline phase. The temperature coefficient of the dielectric constant (TCε) becomes negative as the SrTiO3 phase crystallized out in the glass ceramics and the value of the dielectric constant increases with a higher crystallization temperature and time which finally decides the amount of the SrTiO3 phase. Attempts have also been made to correlate the observed dielectric behavior with the electrical contribution of various crystalline phases, residual glassy matrix, crystal-glass interface region and electrode contribution using the impedance spectroscopic technique.

Synthesis and characterization of hybrid Ag-ZnO nanocomposite for the application of sensor selectivity

Sharma, Sanjeev K.,Ghodake, Gajanan S.,Kim, Deuk Young,Kim, Dae-Young,Thakur, O.P. ELSEVIER 2018 CURRENT APPLIED PHYSICS Vol.18 No.4

<P>Facile, rapid, and environmentally benign hybrid Ag-ZnO nanocomposites were synthesized by two steps from green synthesis approach at room temperature. The absence of an impurity peak in X-ray diffraction (XRD) pattern confirmed the formation of polycrystalline nanocomposite material. An additional peak (111) of Ag was detected along with ZnO crystalline wurtzite structure. The surface area electron diffraction (SAED) pattern further confirmed the crystallinity of nanocomposites. The compositional analysis of hybrid Ag-ZnO was determined by EDS-mapping and confirmed the presence of Zn, O and Ag in the composite. The room-temperature photoluminescence (PL) spectra of hybrid Ag-ZnO depict a weak ultraviolet (UV) emission at 385 nm, and the strong visible emission at similar to 600 nm, while increasing the Ag concentration in to ZnO matrix, the UV peak was completely disappeared and major visible peak was moved to similar to 500 nm indicated to the best optimal detection peak for sensors. The fluorescence spectra were measured with respect to Ag concentrations of Ag-ZnO nanocomposite at room temperature to investigate the functionality and the selectivity of nanomaterials. This work opens a notable way to fabricate Ag-ZnO nanohybrids, and makes a significant contribution to the fluorescence based sensor applications. (c) 2018 Elsevier B. V. All rights reserved.</P>

Structural and electrical properties of microwave -processed BaTiO3 ceramics

ChandraPrakash,O.P.Thakur,D.K.Agrawal 한양대학교 세라믹연구소 2002 Journal of Ceramic Processing Research Vol.3 No.2

Barium titanate (BaTiO3) was synthesized and sintered by microwave processing at 2.45 GHz. Appropriate amounts of BaCO3 and TiO2 were used as starting materials for the synthesis. BaTiO3 phase was obtained by heating the precursors in a multimode microwave cavity at 1450oC for just 25 minutes. The synthesis and sintering were carried out in air. A relative density of 97% was obtained. By contrast, it was found that to achieve the same densification, it required 4 hours of soaking at 1450oC in a conventional sintering process. The dielectric properties show the abrupt discontinuities in dielectric constant vs. temperature plots; typical properties of first order transitions. Above the Curie temperature the dielectric constant follows Curie-Weiss law with Curie constant C=1.3-1.4´105 oC.

Equivalent circuit model of a PbZr0.6Ti0.4O3 ceramic using impedance spectroscopy

Pramod Chaitanya,O. P. Thakur,Vinod Kumar,Alok Shukla,Lakshman Pandey 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.3

The ceramic system PbZr0.6Ti0.4O3 was prepared by a solid state method and impedance measurements were carried out as a function of frequency (100 Hz-10MHz) in the temperature range 370 K-869 K. Equivalent circuit models that represent the data below and above the transition temperature were arrived at by comparing the experimental plots with the computersimulated behavior obtained for model circuits. Below the transition temperature the equivalent circuit model comprises a series LCR combination connected in series with a parallel RC network where as for higher temperatures it contains three parallel RC circuits connected in series. Variation of the values of the components as a function of temperature was also studied.

Synthesis and ferroelectric behavior of Gd doped BNT ceramics

Vijayeta Pal,R.K. Dwivedi,O.P. Thakur 한국물리학회 2014 Current Applied Physics Vol.14 No.1

In the present work, polycrystalline (Bi1xGdx)0.5Na0.5TiO3 (BGNT) ceramics with low amount of rare earth ion Gd3þ (x ¼ 0, 0.02, 0.03, 0.04) have been synthesized by a semiewet technique. XRD patterns show single phase formation for all the samples with a rhombohedral structure at room temperature. FESEM images show decrease in grain size with Gd concentration. The temperature dependence of dielectric constant has revealed that the depolarization temperature ‘Td’ decreases with increasing x and the temperature ‘Tm’ of maximum dielectric constant increases initially for x ¼ 0.02 thereafter decreases. All the samples have shown saturated hysteresis (PeE) loop at room temperature. The BGNT ceramic system for composition, x ¼ 0.02 exhibits improved piezoelectric properties and strong ferroelectricity. With increasing temperature, polarization has been found to be reduced and deformed PeE loops are observed around ‘Td’.

Synthesis and characterization of hybrid Ag-ZnO nanocomposite for the application of sensor selectivity

Sanjeev K. Sharma,Gajanan S. Ghodake,김득영,김대영,O.P. Thakur 한국물리학회 2018 Current Applied Physics Vol.18 No.4

Facile, rapid, and environmentally benign hybrid Ag-ZnO nanocomposites were synthesized by two steps from green synthesis approach at room temperature. The absence of an impurity peak in X-ray diffraction (XRD) pattern confirmed the formation of polycrystalline nanocomposite material. An additional peak (111) of Ag was detected along with ZnO crystalline wurtzite structure. The surface area electron diffraction (SAED) pattern further confirmed the crystallinity of nanocomposites. The compositional analysis of hybrid Ag-ZnO was determined by EDS-mapping and confirmed the presence of Zn, O and Ag in the composite. The room-temperature photoluminescence (PL) spectra of hybrid Ag-ZnO depict a weak ultraviolet (UV) emission at 385 nm, and the strong visible emission at ~600 nm, while increasing the Ag concentration in to ZnO matrix, the UV peak was completely disappeared and major visible peak was moved to ~500 nm indicated to the best optimal detection peak for sensors. The fluorescence spectra were measured with respect to Ag concentrations of Ag-ZnO nanocomposite at room temperature to investigate the functionality and the selectivity of nanomaterials. This work opens a notable way to fabricate Ag-ZnO nanohybrids, and makes a significant contribution to the fluorescence based sensor applications.