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Pandey A.,Bhabha Atomic Research Center | Kelkar A.,Bhabha Atomic Research Center | Singhal R.K.,Analytical Chemistry Division | Baghra C.,Bhabha Atomic Research Center | And 3 more authors.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2012

Pyrohydrolysis is a fast, reliable and convenient method for the decomposition of solid refractory samples. Thoria based mixed oxide nuclear fuels requires more than 1,200 C reaction temperature to lose its structural integrity so as to release the halides. In the present paper, we report WO 3 accelerated pyrohydrolytic extraction technique for the separation of F- and Cl- from thoria based fuels along with the feasibility of using MoO3 and V2O5. The mechanism of extraction has been investigated in detail using X-ray diffraction and recovery studies. ThO2 along with its halides undergo high temperature solid state reaction with WO3 forming Th(WO 4)2 and releasing the halides for their subsequent hydrolysis. The quantification was carried out by ion chromatography with suppressed ion conductivity detection. The average recoveries of the spiked samples for F- and Cl- were 93-99%. The method was successfully applied for simultaneous determination of F- and Cl - in thorium based nuclear fuel samples at 950 C. © 2012 Akadémiai Kiadó, Budapest, Hungary.

Rao P.,Solid State Physics Laboratory | Kumar S.,National Center for Compositional Characterisation of Materials | Raje N.,Analytical Chemistry Division | Tokas R.B.,Atomic and Molecular Physics Division | Sahoo N.K.,Atomic and Molecular Physics Division
Materials Research Bulletin | Year: 2016

CuS, In2S3, CuInS2 and CuGaS2 semiconductors have been synthesised in powder form by precipitation reaction using Na2S·3H2O as a precipitating agent. Precipitated at about 313 K in aqueous medium, the powders of CuS crystallise in covellite (hexagonal) phase and those of In2S3, CuInS2 and CuGaS2 in tetragonal phase on heat treatment in argon atmosphere. The formation of CuS or In2S3 takes place due to the reaction between the metal and bisulphide ions in aqueous phase while that of CuInS2 or CuGaS2 involves solid state reaction between CuS and In2S3 or GaxSy during heat treatment and is accompanied with the evolution of SO2 gas. The powders are nearly monophasic, exhibit nanometric morphology and bear their respective stoichiometric compositions. The direct band gaps of CuS, In2S3, CuInS2 and CuGaS2 measure 2.06, 2.3, 1.34 and 2.38 eV respectively. The method is simple and is extended to the synthesis of CuIn0.8Ga0.2S2 as well. © 2016 Elsevier Ltd. All rights reserved.

Kumar S.,National Center for Compositional Characterization of Materials | Reddy G.L.N.,National Center for Compositional Characterization of Materials | Rao P.,National Center for Compositional Characterization of Materials | Verma R.,Analytical Chemistry Division | And 3 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2012

An indirect method to determine Li by 74Ge(n,γ) 75mGe activation reaction induced in a high purity Ge (detector) crystal by neutrons from the 7Li(p,n) 7Be reaction in a typical particle-induced γ-ray emission (PIGE) spectroscopy experimental set-up is described. Performed with proton beams of energies in excess of 1.88 MeV, the threshold energy (E th) of the 7Li(p,n) 7Be reaction, the determination involves the activity measurement of 75mGe isotope that has a half-life of 47.7 s and decays with the emission of 139 keV γ-rays. Rapidity, selectivity and sensitivity down to ppm levels are the attractive features of the method. It is a suitable alternative to 7Li(p,p′γ) 7Li reaction based PIGE technique in the analyses of matrices that contain light elements such as Be, B, F, Na and Al in significant proportions. Interferences can arise from elements, for example V and Ti, that have E th ≤ 1.88 MeV for (p,n) reaction. In the case of elements such as Cu, Mo which have with E th > 1.88 MeV, the incident proton beam energy can be judiciously selected to avoid or minimize an interference. The method, under optimized irradiation conditions, does not entail a risk of neutron stimulated degradation of the performance of the detector. Besides analytical purposes, the measurement of the 75mGe activity can serve as a powerful tool to monitor even low (∼25 n/cm 2 s) thermal neutron fluxes. © 2011 Elsevier B.V. All rights reserved.

Kumar S.,National Center for Compositional Characterization of Materials | Sunitha Y.,National Center for Compositional Characterization of Materials | Reddy G.L.N.,National Center for Compositional Characterization of Materials | Sukumar A.A.,National Center for Compositional Characterization of Materials | And 3 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2016

The paper presents a proton induced γ-ray emission method based on 18O(p,αγ)15N nuclear reaction to determine bulk oxygen in materials. The determination involves the measurement of 5.27 MeV γ-rays emitted following the de-excitation of 15N nuclei. A description of the energetics of the reaction is given to provide an insight into the origin of 5.27 MeV γ-rays. In addition, thick target γ-ray yields and the limits of detection are measured to ascertain the analytical potential of the reaction. The thick-target γ-ray yields are measured with a high purity germanium detector and a bismuth germanate detector at 0° as well as 90° angles in 3.0-4.2 MeV proton energy region. The best limit of detection of about 1.3 at.% is achieved at 4.2 MeV proton energy for measurements at 0° as well 90° angles with the bismuth germanate detector while the uncertainty in quantitative analysis is <8%. The reaction has a probing depth of several tens of microns. Interferences can arise from fluorine due to the occurrence of 19F(p,αγ)16O reaction that emits 6-7 MeV γ-rays. The analytical potential of the methodology is demonstrated by determining oxygen in several oxide as well as non-oxide materials. © 2016 Elsevier B.V. All rights reserved.

Anubala S.,Natural Product Chemistry Division | Sekar R.,Analytical Chemistry Division | Narayana P.S.,Analytical Chemistry Division | Nagaiah K.,Indian Institute of Chemical Technology
Journal of Planar Chromatography - Modern TLC | Year: 2015

Piperine (PIN), a bioenhancer, is co-formulated with rifampicin (RFN) and isoniazid (INZ) to enhance the bioavailability of RFN. RFN and INZ are the drugs of first choice for the treatment of tuberculosis and recommended by the World Health Organization (WHO). A new high-performance thin-layer chromatographic (HPTLC) method was optimized for the separation and determination of RFN, INZ, and PIN in the bioenhanced pharmaceutical formulation. Separation was performed on a precoated silica gel 60 F254 plate, and an acceptable separation was achieved using a mobile phase comprising toluene-ethyl acetate-methanol (7:3:3, v/v); detection was performed at 300 nm. The proposed method was validated for specificity, accuracy, repeatability, limit of detection, limit of quantification, stability, and robustness. The correlation coefficient (Rsup) values for RFN, INZ, and PIN were 0.9997, 0.9995, and 0.9987, respectively. The spots were identified by matching with the RF values and absorbance spectrum with authentic compounds. The mean recovery (%) values for RFN, INZ, and PIN were 99.3, 99.8, and 99.2%, respectively. The results obtained with the proposed method have been compared with those previously reported for high-performance liquid chromatographic (HPLC) methods. The major degradation products of RFN: 3-formyl rifamycin, isonicotinyl hydrazone (INH), and rifampicin quinone did not interfere with the determination of active pharmaceutical ingredients (APIs). The proposed method is also suitable for the detection of some major RFN-related impurities in pharmaceutical dosage form. © 2015 Akadémiai Kiadó, Budapest.

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