http://nopr.niscair.res.in/handle/123456789/2 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/18344 Title: Sodium anthraquinone-2-sulphonate sensitized photoreduction of methylene violet <br/> <br/>Authors: Bansal, W R; Singh, Kulvir <br/> <br/>Abstract: Sodium anthraquinone-2-sulphonate sensitizes the photoreduction of methylene violet in aqueous medium in the presence of hydrogen donors, isopropyl alcohol and benzhydrol, to give leuco methylene violet. Reduction takes place by reducing sodium anthraquinone-2-sulphonate produced through hydrogen abstraction by excited triplet state of sodium anthraquinone-2- sulphonate from the hydrogen donors. Effect of viscosity and role of electron transfer have been examined by adding ethylene glycol and triethylamine respectively. ϕ_LMV reaches a plateau at 4.0 and 1.7×10^-2 mol dm^-3 of IPA and BPH₂ concentrations where ϕ_LMV = 1.7 and 1.0 respectively. Difference in maximum quantum yields in the case of IPA and BPH₂ has been explained. ϕ_LMV is not afected by viscosity change. <br/> <br/>Page(s): 1652-1656 http://nopr.niscair.res.in/handle/123456789/18343 Title: Differential pulse polarographic determination of lead (II) in complex materials after adsorption of its trifluoroethylxanthate-cetyl-trimethylammonium ion-associated complex on microcrystalline naphthalene or on trifluoroethylxanthate cetyltrimethylammonium- naphthalene adsorbent <br/> <br/>Authors: Puri, B K; Atamjyot; Lal, Keemti; Bansal, Himanshu <br/> <br/>Abstract: Lead(II) is adsorbed as lead trifluoroethylxanthate (TFEX) cetyltrimethylammonium (CTMA) ion pair complex on microcrystalline naphthalene quantitatively in the <i>p</i>H range 4.50- 10.50. In the absence of cetyltrimethylammonium as the counter ion, the adsorption is only 80%. Lead(II) is desorbed with HCl and determined with a differential pulse polarograph. Dissolved oxygen is removed by adding 3 ml of 4% NaBH₄ solution. Alternatively, lead (II) can be quantitatively adsorbed on TFEXCTMA- naphthalene adsorbent packed in a column at a flow rate of 1-2 ml min^-1.Well defined peak has been obtained in this medium at -0.40 V versus S.C. E. Cyclic voltammetric, differential polarographic and D.C. polarographic studies indicate that lead(II) has been reduced reversibly in a two-electron reduction under these conditions. The detection limit is 0.20 μg ml^-1 at the minimum instrumental settings (signal-to-noise ratio =2). Linearity is maintained in the concentration range 0.5 -16.40μg ml^-1 with correlation factor of 0.9997 and a relative standard deviation of ±l.07%. Various parameters such as the effect of <i>p</i>H, volume of aqueous phase, flow rate and the interference of a large number of metal ions and anions on the determination of lead(II) have been studied in detail to optimize the conditions for its trace determination in various standard alloys, standard biological materials and environmental samples. <br/> <br/>Page(s): 1646-1651 http://nopr.niscair.res.in/handle/123456789/18342 Title: Simultaneous second derivative spectrophotometric determination of nickel(II) and copper(II) using diacetylmonoxime isonicotinoyl hydrazone <br/> <br/>Authors: Chandrasekhar, K B; Reddy, K Hussain <br/> <br/>Abstract: A derivative spectrophotometric method, based on the use of second-derivative absorption spectra, has been developed for the simultaneous determination of nickel (II) and copper(II) in aqueous medium using diacetylmonoxime isonicotionyl hydrazone (DMIH). The reagent gives intense colour reaction with nickel(II) and copper(II) in basic medium. The zero-order spectrophotometric method for the determination of these metal ions has been developed in aqueous medium. The molar absorptivity and Sandell's sensitivity for nickel(II) and copper(II) are 1.75×10⁴; 1.12×10⁴ lit. Mol^-1 cm^-1 and 0.00335, 0.00565 μg of metal/cm² respectively. Beer's law is obeyed in the range 0.235-2.35 and 0.25-2.54 μg/ml<i> </i>for Ni(II) and Cu(II) respectively. The proposed simultaneous method involves the use of peak-to-base line measurement techniques. <br/> <br/>Page(s): 1643-1645 http://nopr.niscair.res.in/handle/123456789/18341 Title: Synthesis and characterization of some phthalanilic and maleanilic acid derivatives of arsenic(III) <br/> <br/>Authors: Chauhan, H P S; Singh, R K; Porwal, B; Kori, Kavita <br/> <br/>Abstract: Replacement reaction of arsenic trichloride and 2-chloro- 1,3- dithia-2 -arsacyclopentane with sodium salts of phthalanilic and maleanilic acids (prepared <i>in situ </i>by the reaction of corresponding anilic acids with sodium isopropoxide in the mixture benzene and isopropanol) in the 1:3 and 1:1 molar ratios respectively, in benzene and isopropanol mixture, yield the arsenic derivatives of the type [L]₃ As and [L] AsSCH₂CH₂S (where L = phthalanilate and maleanilate anions). These derivatives have been characterized by elemental analysis as well as IR and ¹H NMR spectral studies. <br/> <br/>Page(s): 1639-1642