Solvent extraction of La(III) using Cyanex 921 in petrofin and modelling of data by linear and nonlinear techniques

Journal of Radioanalytical and Nuclear Chemistry - Influence of various parameters affecting the extraction of La(III) from acidic nitrate medium has been analysed. The extraction of 99.1% La(III)...     

A sensitive colorimetric method for the micro determination of iodine in marine water

More than 70% of the earth surface is covered by water bodies. Marine pollution is associated with the discharge of oils, petroleum products, sewage agricultural wastes, pesticides, heavy metals, waste substances and dumping of radioactive waters in sea. This in turn results in hazards to human health, hindrance to aquatic organisms and impairment of quality for use of sea water. Sea water is reported to contain iodine but the concentration varies according to the location and depth. Here a simple and sensitive method is described for the determination of iodine using leucocrystal violet as a reagent in different samples of sea water. The method is based on the oxidation of iodine to iodate with bromine water and the liberation of free iodine from the iodate by addition of potassium iodide in acedic medium. This iodine selectively oxidises leucocrystal violet to form the crystal violet dye. Beer's law is obeyed over the concentration range of 0.04-0.36 ppm of iodine at lambda(max) 592 nm. The dye was further extracted in chloroform. The extracting system obeys Beer's law in the range of 0.008-0.08 ppm at lambda(max) 588 nm.     

Purification of α-amylases using magnetic alginate beads

Magnetic alginate beads were used to purify alpha-amylases from porcine pancreas, starchzyme, BAN 240L (a commercial purification from Bacillus subtilis), and wheat germ. The beads bound a significant level of alpha-amylase activity from porcine pancreas, BAN 240L, and wheat germ. In each case, the enzyme activity could be eluted by using 1.0 M maltose, a known competitive inhibitor of alpha-amylase. In the case of BAN 240L, 3.6-fold purification with 72% recovery of activity was observed. In the case of wheat germ enzyme, starting from the crude extract, 48-fold purification with 70% activity recovery was observed. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis also indicated considerable purification in the latter case.     

Electrochemical Sensing of Chlorpyrifos,a Carcinogen Responsible for Breast Cancer,in Milk and Plasma of Lactating Mothers

In view of the increase in breast cancer cases at the global level, electrochemical sensing of the carcinogenic pesticide, chlorpyrifos (CPF) in breast milk is proposed. The determination is based on the nucleophilic substitution reaction of pralidoxime (PAM) with CPF. The proposed method offers a linear concentration range of 0.002 to 0.08 μmol/L. The limit of detection and limit of quantification was found to be 0.05×10⁻⁹ and 0.167×10⁻⁹M, respectively. The offered “unmodified edge plane pyrolytic graphite sensor” proved to be a better substrate than the earlier reported modified sensors. The limit of detection for the proposed method was found to be nearly fifty times lower than reported at modified electrodes. The interference study proved the adequate selectivity of the offered sensor. The sensor has good stability and reproducibility along with high sensitivity. The offered sensor is very useful for cancer hospitals, pesticide industries, and the study of environmental toxicity-related issues.     

Fluorescence Investigation of the Binding of Model PDT Drugs to Nonionic and Zwitterionic Surfactants

The binding of two model photodynamic therapy drugs, chlorin p ₆ and purpurin 18, with surfactants has been studied using steady-state and time-resolved fluorescence techniques. The surfactants used are amphiphilic nonionic surfactant (Tween 80 and Tween 40) and zwitterionic surfactant (HAPS). These have applications in drug delivery. The studies have been performed at pH 7 and 5 for chlorin p ₆ and at pH 7 for purpurin 18. The binding constants have been estimated from the change in fluorescence parameters and have been compared with those for Cremophor EL and human serum albumin. Chlorin p ₆ is found to bind to the surfactants to a greater extent at pH 5 than at pH 7. The same ionic species of chlorin p ₆ is found to exist at the maximum concentrations of the surfactants.     

Voltammetric Determination of 2′‐Deoxyadenosine and Adenine in Urine of Patients with Hepatocellular Carcinoma Using Fullerene‐C60‐modified Glassy Carbon Electrode

A fullerene‐C₆₀‐modified glassy carbon electrode has been examined for the simultaneous determination of 2′‐deoxyadenosine (2′‐dAdo) and adenine in human blood and urine using Osteryoung square‐wave voltammetry (OSWV) at pH 7.2. Compared to bare glassy carbon electrode (GCE), the modified electrode displays a shift of the oxidation potential in the negative direction with significant increase in the peak current for both the analytes. At modified electrode well‐defined anodic peaks at potential of 1248 mV and 994 mV are observed for 2′‐dAdo and adenine respectively. Linear calibration curves were obtained within the concentration range 10 nM to 100 μM for both the compounds in 0.1 M phosphate buffer solution (PBS) with the limit of detection 0.8×10^?8 M and 0.95×10^?8 M for 2′‐dAdo and adenine respectively. The analytical utility of the present method is demonstrated by quantitative detection of 2′‐dAdo and adenine in human urine of normal subjects as well as in patients with hepatocellular carcinoma. Interfering effect of some coexisting metabolites has also been reported.     

Synthesis of poly(thio-1,4-phenylene) by oxidative coupling reaction of diphenyl disulfide with potassium persulfate in strongly acidic solutions

The synthesis of poly(thio- 1,4-phenylene) (PPS) at room temperature by the reaction of diphenyl disulfide with potassium persulfate (K₂S₂O₈) in non-basic solvents, in the presence of trifluoromethanesulfonic acid, is reported. The reaction in chlorinated solvents, such as dichloromethane and tetrachloroethane, resulted in partial oxidation of sulfide to sulfoxide and sulfone. On the other hand, the polymerization proceeded well in nitrobenzene and the PPS formed was free of branches, crosslinks and thianthrene units. The molecular weight of the polymers formed in different solvents were in the range 2000–8000. The reaction proceeded under identical conditions with bis(2,6-dimethylphenyl) disulfide as well, but the polymer yield was lower.     

Quantitation of Oleanolic Acid in Oldenlandia corymbosa L. Whole-Plant Powder by High-Performance Thin-Layer Chromatography

JPC – Journal of Planar Chromatography – Modern TLC - A sensitive, simple, and accurate high-performance thin-layer chro-matographic method has been established for determination of...     

Synthesis,structural studies and some biological aspects,including nematicidal and insecticidal properties,of organotin(IV) complexes formed with biologically active sulfonamide imine ligand

The synthetic, spectroscopic and biological studies of some organotin(IV) complexes derived from sulfonamide imine having a nitrogen–nitrogen donor system have been undertaken. The sulfonamide imine, on interaction with organotin(IV) chlorides, yields complexes having an Sn←N bond. The structures of these compounds have been elucidated by microestimations and spectral (UV, IR, ¹H, ¹³C and ¹¹⁹Sn NMR) studies, which unerringly point to the trigonal bipyramidal and octahedral geometries for the unimolar and bimolar reactions respectively around tin(IV), as the active lone pair of nitrogen is also included in the coordination sphere. Studies were conducted to assess the comparative growth‐inhibiting potential of the synthesized complexes against the sulfonamide imine for a variety of fungal and bacterial strains. The studies demonstrate that the concentrations reached levels sufficient to inhibit and kill the pathogens. The results of the biological studies have also been compared with the conventional standards, Bavistin and Streptomycin, taken for antifungal and antibacterial activities respectively. The complexes also show higher nematicidal and insecticidal properties. Copyright © 2004 John Wiley & Sons, Ltd.