Simultaneous Determination of Se and Te in Ores by HG-AFS After Online Preconcentration with Nano-TiO2 Immobilized on Silica Gel.

A simple, sensitive and interference-free method was established for simultaneous determination of trace selenium and tellurium in ore samples by HG-AFS, by using nano-TiO2 immobilized on a silica gel packed microcolumn for online preconcentration. Selenium and tellurium were selectively adsorbed to the microcolumn in acidic condition and then completely eluted with 2% (m/v) NaOH solution. The experimental conditions for hydride generation, adsorption, elution and potential interference were investigated in detail. Under the optimum conditions, the detection limits of selenium and tellurium by the proposed method with 180 s sampling time were 4.0 and 3.6 ng · L(-1), with sensitivity enhancement of 20- and 13-fold compared to conventional hydride generation method, respectively. The relative standard deviation (RSD, n=5) of this method for 1 µg · L(-1) Se(IV) and Te(IV) were 0.7% and 2.3%, respectively. This method was applied to determination of selenium and tellurium in several ore samples.

[N,N'-(1,2-Diphenyl-ethane-1,2-di-yl)bis-(pyridine-2-carboxamidato)]nickel(II) diethyl ether hemisolvate.

In the title compound, [Ni(C(26)H(20)N(4)O(2))]·0.5C(4)H(10)O, the central metal ion is coordinated by four atoms of the tetra-dentate picolinamide ligand, forming a slightly distorted square-planar configuration, with an average Ni-N(pyridine) distance of 1.94 Šand an average Ni-N(amide) distance of 1.83 Å. The asymmetric unit contains one half-molecule of diethyl ether; this solvent molecule is disordered across a twofold rotation axis..