[en] A photometric method for the evaluation of stepwise and overall formation constants of molybdylhydroxo-aminobenzenethiolate chelate has been described. The characterization of the complex has been done on the basis of analysis, thermogravimetric analysis, magnetic susceptibility measurements and IR spectra. The formation of MoO(OH)³⁺ species is explained via protonation of MoO₂(ABT)₂ chelate species as supported by IR spectral studies. The presence of inter- and intra-molecular hydrogen bond in the chelate is indicated by a lowering in νO-H and νN-H frequencies. The stepwise formation constants (log k₁ < log k₂ < log k₃) and overall stability constant (log K or log β₃) are found to be 1.79, 2.82, 3.80 and 8.35 at 25 +- 1 deg C, respectively. The free-energy chan.o.e for the reaction (log K = 8.35) is -11.2 kcal mol^-1. (author)

[en] A photometric method is described for the determination of stepwise and successive formation constants for the 1:4 tungsten-maleonitrile dithiolate system. A new concept on theoretical molar absorptivity is qiven and the theoretical molar absorptivity for the tungsten-maleonitrile dithiolate (W-MNT) complex has been found. The overall constants evaluated by different photometric procedures including the new extrapolation method are compared and discussed. The values of log k₁, log k₂, log k₃, log k₄ and log K or log β₄ are 3.60, 4.45, 3.80, 3.55 and 15.40 respectively. The log K value obtained from mole-ratio curve employing Harvey-Manning's method is 16.10 at 25 +- 1 deg C. The free energy change for the reaction is found to be -20.1 kcal mol^-1 (log K = 15.40). (author)

[en] Vanadium reacts with salicyl hydroxamic acid to form a blue-violet coloured complex with lambdasub(max) at 475 nm at pH 3.3. The metal-ligand ratio in the complex is 1:4. The step-wise formation constants of the complexes have been evaluated by Yatsimirskii's and Leden's graphical extrapolation methods from extractive photometric data. The values from log K₁, log K₃ and log K₂, and log K₄ are 3.65 +- 0.05, 2.50 +- 0.05, 2.30 +- 0.05 and 2.15 +- 0.05 respectively. (author)

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[en] A highly sensitive, selective and rapid solvent extraction procedure for spectrophotometric method of determination of sub trace amount of vanadium(V) in methyl isobutyl ketone has been reported in this paper. Vanadium(V) is extracted with N-cinnamohydroxamic acid (N-CHA) and a mixed ligand thiocyanate (SCN) as a violet coloured complex in solvent phase at 1.8 M HCl. The ternary complex absorbs maximum at 555 nm. The system obeyed Beer's law from 0.4 to 12 ppm with optimum range of determination 1-9 ppm of V(V). The molar absorptivity and Sandell's sensitivity are 0.745 x 10⁴ 1.mole^-1 cm^-1 and 6.8 ng cm^-2 of V(V) at 555 nm. A large number of cations and anions do not interfere. The method shows high selectivity with thiouriede as masking agent and it is simple, rapid, reproducible and reports high precision. The R.S.D. value is ± 0.0012 for average of seven determinations. The photometric determinations are also reported in detail and the standard deviations are minimal. The R.S.D. values are different for the steel (0.08%), rock (2-3%) and ore (2%) samples. (author)

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[en] A new selective photometric method of determination of vanadium (V) in presence of Fe(III) and Ti(IV) is reported. The complex (1:1) absorbs maximum at 490 nm in the optimum acidity range 0.16-0.36 M HCL. The rose-red complex has the molar absorptivity 4.5 x 10³ l mole^-1 cm^-1. The system obeyed Beer's law over the range 1-16 ppm. The method is very simple and free from usual interferences. The metal in alloy steel has been determined with ±0.03% as the average error. (author). 7 refs

[en] Homogenates of brain, liver, kidney, heart and skeletal muscle of rat were prepared in 0.32 M-sucrose containing 2 mM EDTA. The CANP activity was assayed using ¹⁴C-azocasein as substrate in 50 mM Tris acetate buffer, pH 7.4, 0.1% Triton X-100 and 5 mM-β-mercaptoethanol, with and without CaCl₂. Addition to CNS membranes of other non-ionic detergents including sodium deoxycholate, β-D-thiogluco-pyranoside, and cetyltrimethyl-ammonium bromide activated the enzyme to varying extent depending on the detergent concentration. The ionic detergent sodium dodecyl sulfate abolished CANP activity completely in all preparations and this effect could not be reversed by non-ionic detergents. The most interesting feature of the Triton X-100 effect was a ten-fold increase of CNS CANP activity whereas non-neural CANP was not at all induced by Triton. CNS CANP was found mainly in the particulate fraction and only 30% in cytosol. In contrast, non-neural CANP was present mainly in cytosol. These results suggest that the bulk of CANP is membrane bound in CNS and differs from other tissue where it remains cytosolic

[en] A new photometric method for the determination of molybdenum(VI) with 4-hydroxy-coumarinthiol is reported in this paper. The reagent forms a stable intensely coloured violet complex extracted in chloroform. The complex extracted from 1 M HCl absorbs maximum at 560 nm and has the molar absorptivity 1.2 x 10⁴ 1.mole^-1cm^-1. The system conforms to Beer's law from 0.5 to 12 ppm with optimum range 1-7 ppm at 560 nm. The Sandell's sensitivity of the reaction is 0.00812 μg cm^-2 Mo(VI). 7.5 times excess of Cu(II), V(V), W(VI) is tolerated and all other ions do not interfere. The stepwise and overall stability constants of the 1:2 complex have been determined by spectrophotometric methods. (author)