NOPR Collection:

Catalytic kinetic spectrophotometric determination of palladium(II) and its application to the determination of traces of propylthiouracil

Wed, 01 Jun 2005 00:00:00 GMT

Title: Catalytic kinetic spectrophotometric determination of palladium(II) and its application to the determination of traces of propylthiouracil Authors: Jabbari, A; Barzegar, M; Mohammadi, M Abstract: The catalytic-kinetic method has been proposed for the determination of palladium(II) based on its catalytic effect on the reaction of crystal violet with hypophosphite. The reaction has been monitored spectrophotometrically at 590 nm over the range 0.071-2.850 ppm of Pd(II). The influence of reaction variables and the effect of interfering ions have been studied. The limit of detection and relative standard deviation are 0.071 ppm and 2.76%, respectively. The developed method has been applied to the determination of Pd(II) in river water and Pd-C catalyst. The proposed method has also been applied for the determination of propylthiouracil in pharmaceutical samples based on its inhibitory effect on the palladium(II)-catalyzed reaction between crystal violet and hypophosphite ions. The decrease in absorbance of crystal violet at 590 nm is proportional to 1.7-248.0 ppb of PTU. The limit of detection and RSD are 1.7 ppb and 2.53%, respectively. Page(s): 1215-1218

Determination of cadmium(II), copper(II) and zinc(II) in water samples by flame atomic absorption spectrometry after cloud point extraction

Wed, 01 Jun 2005 00:00:00 GMT

Title: Determination of cadmium(II), copper(II) and zinc(II) in water samples by flame atomic absorption spectrometry after cloud point extraction Authors: Shemirani, Farzaneh; Abkenar, Shiva Dehghan; Jamali, Mohammad Reza Abstract: A preconcentration method for determination of low concentrations of Cd(II), Cu(II), and Zn(II) in water, using cloud point extraction is proposed. The analytes in the initial aqueous solution have been complexed with 8-hydroxyquinoline, with 0.06% (w/v) Triton X-114 added as surfactant. The complexation allows the separation of the analytes from other elements, which are not complexed. After phase separation, based on the c loud point of the mixture and dilution of the surfactant-rich phase with acidified methanolic solution, the enriched analytes have been determined by flame atomic absorption spectrometry. After optimization of complexation and extraction conditions, good enrichment factors have been obtained. The detection limits are 0.15 ng ml^-1 for Cd(II), 0.72 ng ml^-1, for Cu(II) and 0.03 ng ml^-1 , for Zn(II) in the initial solution. The relative standard deviations are lower than 3.1 %. The method has been applied for analysis of the studied ions in tap water and river water samples. The method has been validated by the analysis of standard reference material. Page(s): 1211-1214

Chelation ion-exchange properties of 2, 2'-dihydroxybiphenyl-urea-formaldehyde (2:1:3) resin

Wed, 01 Jun 2005 00:00:00 GMT

Title: Chelation ion-exchange properties of 2, 2'-dihydroxybiphenyl-urea-formaldehyde (2:1:3) resin Authors: Jadhao, Manjusha M; Paliwal, L J; Bhave, N S Abstract: The resin 2,2'-dihydroxybiphenyl-urea-formaldehyde [BPhUF], has been synthesized by the condensation of 2,2'dihydroxybiphenyl [BPh] and urea [U] with formaldehyde [F] in 2: 1:3 molar ratio in presence of 2M HCl as a catalyst. UV-Vis, IR and NMR spectral studies have been carried out to elucidate the structure of resin. Ion exchange properties of this resin have been studied by batch equilibrium method for Fe³⁺, Cu²⁺, Ni²⁺, Co²⁺,Zn²⁺, Cd²⁺ and Pb²⁺ ions over the pH range, 1.5 to 6.5 and in media of various ionic strengths. In presence of chloride and nitrate ions, the uptake of Fe³⁺, Cu²⁺ and Ni²⁺ ions increases with increasing concentration of electrolyte while for Co²⁺,Zn²⁺, Cd²⁺ and Pb²⁺ ions, it decreases with increasing concentration of chloride, nitrate and sulphate ions. The resin shows a higher selectivity for Fe³⁺ ion over any other ion. Study of distribution ratio as a function of pH indicates that the amount of metal ion taken up by resin increases with the increasing pH of the medium. Page(s): 1206-1210

Ultrasonic studies of substituted isoxazoles and pyrazolines in dioxane and dioxane-water mixtures at different temperatures

Wed, 01 Jun 2005 00:00:00 GMT

Title: Ultrasonic studies of substituted isoxazoles and pyrazolines in dioxane and dioxane-water mixtures at different temperatures Authors: Ikhe, Shashikant A; Narwade, M L Abstract: Ultrasonic velocities and densities of 3-(2-hydroxy-3-bromo-5-methylphenyl)-5-phenyl isoxazole (L₁), l-phenyl-3-(2-hydroxy-3-bromo-5-methylphenyl)-5-(4-methoxyphenyl) pyrazoline (L₂), in dioxane and different percentages of dioxane-water mixtures at different temperatures (303, 308, 313, 318, 323 K ± 0.1 K) have been evaluated at 0.01 M concentration. Different acoustic properties like partial molal volume (ϕ_v), adiabatic compressibility (β_s), apparent molal compressibility (ϕ_k(s)) intermolecular free length (L_f), relative association (R_A) and specific acoustic impedance (Z) have been determined by using single crystal interferometer at 1MHz frequency. The obtained results have been interpreted in terms of solute solvent interactions. Page(s): 1203-1205