Determination of copper,nickel, manganese and cadmium ions in aqueous samples by flame atomic absorption spectrometry after simultaneous coprecipitation with Co(OH)2

A separation-preconcentration procedure was developed for the determination of trace amounts of copper, nickel, manganese and cadmium ions in water samples by flame atomic absorption spectrometry after coprecipitation by Co(OH)₂ as a carrier without a chelating agent. The influence of the various analytical parameters such as pH, amount of carrier reagent, standing time, centrifugation rate and time, sample volume and matrix effects on the recovery of the analyte ions was studied. Under the specified experimental conditions the calibration curves for Ni(II) and Cu(II) were linear from 0.5 to 200 ng mL^?1 and for Mn(II) and Cd(II) from 0.5 to 250 and 0.3 to 80 ng mL^?1, respectively. The relative standard deviations for seven replicate determinations of a mixture of 40.0 ng mL^?1 of Cu(II), Ni(II), Mn(II) and 20 ng mL^?1 of Cd(II) in the original solution were 1.9%, 1.7%, 1.8% and 2.1%, respectively. The detection limits based on 3S_b/m for Cu(II), Ni(II), Mn(II) and Cd(II) in the original solution were 0.2, 0.2, 0.3 and 0.07 ng mL^?1, respectively. The limits of quantification based on 10S_b/m for Cu(II), Ni(II), Mn(II) and Cd(II) in the original solution were 6.7, 6.7, 10.0 and 2.3 ng mL^?1, respectively. The proposed method has been applied to the determination of trace amounts of the analyte ions in two certified reference materials (the National Institute for Environment Studies (NIES) No. 1 Pepperbush and NIES No. 7 Tea Leaves) and water samples and satisfactory results were obtained.     

The crystal structure of μ-Oxo-bis{diethoxy[salicylaldoximato(2-)]-tantalum(V)}

Stochiometric reaction of salicylaldoxime and tantalum or niobium ethoxide in toluene at room temperature resulted in formation of [M₂O(C₇H₅NO₂)₂(C₂H₅O)₄], M=Ta and Nb which were crystallized from CH₂Cl₂ at −5 °C and characterized by spectroscopic techniques. The molecular structures of [Ta₂O(C₇H₅NO₂)₂(C₂H₅O)₄] was determined by single-crystal X-ray diffraction and compared with molecular structure of [Nb₂O(C₇H₅NO₂)₂(C₂H₅O)₄]. The geometries at metal atoms are distorted octahedron which shared an apex through bridged oxygen. Each dianionic salicylaldoximate ligand chelates to the one metal ion through its phenolic oxygen and oximate nitrogen atoms, and to another metal ion through its oximate oxygen atom.     

A solvent-free synthesis of 1,2,3,5-tetrasubstituted pyrroles from enaminones and α-haloketones

A simple synthesis of 1,2,3,5-tetrasubstituted pyrrole derivatives from the reaction of enaminone withα-haloketones,under solvent-free conditions,is described.     

Friedländer synthesis of poly‐substituted quinolines in the presence of triethylammonium hydrogen sulfate [Et3NH][HSO4] as a highly efficient,and cost effective acidic ionic liquid catalyst

A rapid and an efficient method for the preparation of a variety of substituted quinolines has been developed through the reactions of o‐aminoarylketones with carbonyl compounds containing a reactive α‐methylene moiety in the presence of molten [Et₃NH][HSO₄] under solvent‐free conditions in high yields. J. Heterocyclic Chem., (2011).     

Modified nanoalumina sorbent for sensitive trace cobalt determination in environmental and food samples by flame atomic absorption spectrometry

1-(2-pryidylazo)-2-naphthol (PAN) immobilized on sodium dodecyl sulfate-coated nano alumina was developed for the preconcentration and determination of metal cations Co (II) from environmental and food samples. The research results displayed that adsorbent has the highest adsorption capacity for Co (II) in this system. Desorption by elution of the adsorbent with 2.0?ml of a mixture of nitric acid and ethanol was carried out. After phase separation, the enriched analyte in the final solution is determined by flame atomic absorption spectrometry (FAAS) by using a micro sample introduction system. Analytical influencing parameters including pH value, amount of sorbent, equilibrium time, sample volume, volume and concentration of eluent were examined. The effect of common matrix ions has also been investigated and it was found that they had no influence on cobalt preconcentration. Under the optimum experimental conditions, the maximum capacity of sorbent was obtained as 20?mg?g^?1. The preconcentration factor and limit of detection were found to be 250 and 0.15?µg?L^?1, respectively. This method showed good precision with the relative standard deviation (RSD) of 2.4% and 2.1% in concentrations of 20 and 50?µg?L^?1, respectively. The accuracy of the method was evaluated by comparison of results with those obtained by electrothermal atomic absorption spectrometry. This method was successfully applied for preconcentration and determination of Co (II) in environmental and food samples.