NOPR Collection:

Mixed-ligand stability constants of divalent metal ions with glycine and hydroxamic acids

2016-07-20T04:36:14Z

Title: Mixed-ligand stability constants of divalent metal ions with glycine and hydroxamic acids Authors: Agrawal, Y K; Menon, S K; Parekh, P C Abstract: The thermodynamic mixed ionization constants, pKof N-m-chlorophenyl-p-substituted benzohydroxamic acids and glycine have been determined in 0.083 to 0.24 mole fraction of dioxane (n₂) 25°C. The mixed pK 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. Page(s): 1313-1318

Speciation of cobalt, zinc and mercury in marine environment

2016-07-20T04:35:34Z

Title: Speciation of cobalt, zinc and mercury in marine environment Authors: Toteja, R S D; Sudersanan, M; Iyer, R K 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. Page(s): 1367-1372

Selective spectrophotometric determination of cerium(IV)

2016-07-20T04:34:41Z

Title: Selective spectrophotometric determination of cerium(IV) Authors: Vijayalekshmy, B; Biju, V M; Rao, T Prasada 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. Page(s): 1365-1366

Kinetic - spectrophotometric determination of trace amounts of selenium(IV) based on its catalytic effect on the reduction of brilliant green by sulphide ion

2016-07-20T04:34:01Z

Title: Kinetic - spectrophotometric determination of trace amounts of selenium(IV) based on its catalytic effect on the reduction of brilliant green by sulphide ion Authors: Parham, H; Jafarpoor, J 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 1μg 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. Page(s): 1362-1364