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  • Author or Editor: P. Reddy x
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Neodymium zirconyl oxalate (NdZrOX) is prepared and characterized by chemical analysis and ir spectral studies. Its thermal decomposition has been investigated by using DTA, TG, DTG, X-ray diffraction and ir spectroscopy. On the basis of thermogravimetry and isothermal studies a probable mechanism for the decomposition is proposed. The decomposition proceeds mainly through three stages: i) dehydration between RT-413 K, ii) decomposition of oxalate between 413–943 K and iii) decomposition of the carbonate between 1028–1235 K to give a mixed oxide. The ir spectra and X-ray diffraction studies are made for identification of the intermediates. X-ray diffraction studies of the end product indicates that it belongs to cubic crystal system witha=11.520 Å.

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Reactions of recoil80, 80mBr with CH2ClBr and CCl3Br have been investigated. Relative reactivities of recoil bromine atoms in binary mixtures of CH2ClBr and CCl3Br with c–C6H12, CH3OH and C6H5N/CH3/2 have been determined using the model developed by Kontis and Urch.

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A rapid and sensitive method has been developed for the determination of microgram amounts of chromium based on the radiochemical displacement of65Zn from labeled Zn-[1-(2-pyridylazo-2-naphthol]2 complex by chromium. The effect of pH on the displacement of65Zn was studied. 5–65 g of chromium could be determined with great accuracy. The effect of various ions on the displacement of65Zn by chromium was investigated and the method developed was utilized for the determination of chromium content present in geological water samples. The results were compared with values obtained by Atomic Absorption Spectrophotometry.

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A quantitative densitometric high-performance thin-layer chromatographic (HPTLC) method has been established for analysis for two anti epileptic drugs, levetiracetam and oxcarbazepine in tablets. Separations on silica gel 60 F 254 HPTLC plates with toluene-acetone-methanol, 6:2:2 ( v/v ), as mobile phase enabled satisfactory resolution of the two drugs. This system afforded well resolved compact bands for levetiracetam and oxcarbazepine at R F 0.45 ± 0.02 and 0.55 ± 0.02, respectively. Densitometric scanning was performed in absorbance/reflectance mode at 200 and 261 nm. The method was successfully validated for precision, robustness, ruggedness, and recovery. The drugs were also subjected to photodegradation studies; oxcarbazepine was degraded in 9 h and levetiracetam was not degraded even after a long period. The method was found to be accurate and compatible with the conditions used.

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A number of essential trace elements play a major role in various metabolic pathways and in many diseases like autoimmune, neurological and psychiatric. This study is undertaken with an aim to evaluate the levels of different trace elements in the scalp hair samples of patients suffering from alcohol induced psychosis by particle induced X-ray emission technique (PIXE). It is observed that Fe (p < 0.0005), Cu (p < 0.001) are significantly higher in the hair samples of alcohol induced psychosis patients compared to those in normals while concentrations of Mn (p < 0.005) and Zn (p < 0.0001) are lower. The concentrations of Co and Ni in the hair samples are found to be in consonance with the concentrations in the normals.

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A chemical neutron activation analysis method to determine trace amounts of palladium present in the uranium ores has been developed. Palladium was concentrated on an anionic exchanger to purify from large amounts of uranium, iron and copper that were present in the ore. The resin in which Pd was adsorbed was neutron irradiated and the activation product109Pd was assayed through its daughter109mAg by low energy photon spectrometry to estimate palladium. Both the 88 keV gamma-line and the 22 keV X-ray line (arising out of the internal transition of109mAg) were used to arrive at the concentration values by a standard comparison technique. A thin window Si(Li) detector and an HPGe detector were used for the radioactive assay. Detection limits and the advantage of using the X-ray line of Ag over that of the gamma-line were discussed. An absolute detection limit of 0.12·10−9 g could be arrived at by the use of the 22.10 keV X-ray line in an interference-free condition.

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Synergism in the extraction of Ce(III) from thiocyanate solutions has been investigated using mixtures of 2-thenoyltrifluoroacetone (HTTA) and bis-2-ethylhexyl sulfoxide (B2EHSO) or di-n-octyl sulfoxide (DOSO) in benzene. A very high synergistic enhancement of the order of 105 has been observed. If a mixture of both dialkyl sulfoxides (B2EHSO+DOSO) is used, an additional synergistic effect is found due to the formation of a mixed, solvated complex when both reagents are added to the metal chelate. These extraction data have been analyzed theoretically with the aid of a computer by taking into account complexation of the metal in the aqueous phase by inorganic ligands and plausible complexation in the organic phase. The equilibrium constants of the various product species have been deduced by non-linear regression analysis.

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Multielement analysis was carried out in two samples of natural rubies obtained from Kenya and Tanzania and a synthetic ruby obtained locally. The trace element profile was used to characterise the ruby samples. Instrumental Neutron Activation Analysis (INAA) by the single comparator (K 0 method) was used to determine the concentrations of 22 elements with gold as the comparator. High resolution -ray spectrometry was employed for radiometric assay of the activation products. The accuracy and precision were evaluated by analysing standard reference materials such as USGS-W-1 and AGV-1 and were found to be satisfactory.

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A radiochemical displacement method has been developed for the determination of nickel and cobalt based on the release of Zn-65 from labelled Zn(PAN)2 [1-(2-pyridylazo) 2-naphthol] complex in chloroform. The displacement behavior of Zn-65 by nickel and cobalt was studied in the pH range 5–7.5. The effect of various ions on the displacement was also examined. 2–20 g of nickel and cobalt was determined by the aid of calibration plots.

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