http://nopr.niscair.res.in/handle/123456789/59 http://nopr.niscair.res.in/retrieve/137 http://nopr.niscair.res.in/handle/123456789/59 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/18648 Title: Mixed-ligand stability constants of divalent metal ions with glycine and hydroxamic acids <br/> <br/>Authors: Agrawal, Y K; Menon, S K; Parekh, P C <br/> <br/>Abstract: The thermodynamic mixed ionization constants, <i>pK</i><img src='http://www.niscair.res.in/jinfo/ab.gif' border=0>of N-<i>m</i>-chlorophenyl-<i>p</i>-substituted benzohydroxamic acids and glycine have been determined in 0.083 to 0.24 mole fraction of dioxane (n₂) 25°C. The mixed <i>pK</i><img src='http://www.niscair.res.in/jinfo/ab.gif' border=0> are correlated with the Hammett equation. The determined stability constants have been found to follow the order Pd(II) > Cu(II) > Ni(II) > Zn(II)> Co(II) > Fe( II) > Mn(II) and these also follow the order of basicities of the ligands. The linear free-energy relationship for the particular set of metal ions and the set of ligands is calculated and compared.   <br/> <br/>Page(s): 1313-1318 http://nopr.niscair.res.in/handle/123456789/18647 Title: Speciation of cobalt, zinc and mercury in marine environment <br/> <br/>Authors: Toteja, R S D; Sudersanan, M; Iyer, R K <br/> <br/>Abstract: Speciation of cobalt, zinc and mercury has been investigated using solid and liquid ion exchangers. Batch equilibration method and column chromatography have been used to speciate the metal ions. Cobalt species is found to be present mainly as a monopositive ion with an appreciable concentration of cobalt sulphate complexes. The uptake from anion exchanger is found to be less. In case of zinc, the metal ion is found to exist partly in the cationic, anionic and hydrolysed forms which exist in labile equilibrium. Mercury has been found to exist mainly as anionic chloro complexes alongwith hydrolysed or organically bound complexes. In all the cases, there is a good agreement with the data obtained using simulated and actual sea water, indicating that the general speciation of the metal ion is governed by the anions like chloride, sulphate and carbonate/hydroxide present in sea water. <br/> <br/>Page(s): 1367-1372 http://nopr.niscair.res.in/handle/123456789/18646 Title: Selective spectrophotometric determination of cerium(IV) <br/> <br/>Authors: Vijayalekshmy, B; Biju, V M; Rao, T Prasada <br/> <br/>Abstract: A simple and highly selective spectrophotometric method has been described for the determination of cerium(IV). The method is based on the measurement of decrease in absorbance at 525 nm of Rhodamine 6G in sulphuric acid medium. The decrease in absorbance is instantaneous on addition of ceriurn(IV) and remains stable for 2 days. The suitability of the method for the determination of cerium(IV) at concentrations greater than 0.01 μg/ml in other high purity rare earth oxides and sea water has been demonstrated. <br/> <br/>Page(s): 1365-1366 http://nopr.niscair.res.in/handle/123456789/18645 Title: Kinetic - spectrophotometric determination of trace amounts of selenium(IV) based on its catalytic effect on the reduction of brilliant green by sulphide ion <br/> <br/>Authors: Parham, H; Jafarpoor, J <br/> <br/>Abstract: A simple, rapid and sensitive kinetic-spectrophotometric method for the determination of trace amounts of Se(IV) (0.02-2.50μg ml^-1) based on its catalytic effect on the reduction of brilliant green by sodium sulphide is reported. The reaction is followed spectrophotometrically by measuring the rate of decrease in absorbance of the brilliant green at 625 nm and 25 °C. A fixed time method of 1.5 min from initiation of the reaction has been used. The limit of detection is 12 ng ml^-1 and the relative standard deviation for ten replicate analysis of 1μ<i>g </i>ml^-1 of Se(IV) is 1.25%. The parameters influencing the sensitivity have been optimized. The proposed method has been used for the determination of Se(IV) in an antiseborrheic 1% selenium sulphide shampoo. <br/> <br/>Page(s): 1362-1364