Study of metal-loaded activated charcoals for the separation and determination of selenium species by energy dispersive X-ray fluorescence analysis

Conversion of adsorption properties of activated charcoal (C^∗) by metal modification towards selenite, selenate and seleno-dl-methionine (Se-Met) was studied. Several metals were included in modification studies and also a procedure was developed for the separation and independent determination of microgram quantities of these selenium species in aqueous solution. Selenium species were collected one by one from the same sample solution onto collector material by adsorbing them directly or after complex formation onto different metal-loaded activated charcoals (MgC^∗ and FeC^∗). The mass of selenium in these collectors was measured directly by energy dispersive X-ray fluorescence spectrometry (EDXRF). Detection limits for all three selenium species were better than 6 μg corresponding to concentration of 60 μg/l with 0.100 l of initial sample volume.     

Zirconium-loaded activated charcoal as an adsorbent for arsenic, selenium and mercury

The adsorption of arsenic, selenium and mercury from aqueous solutions onto zirconium-loaded activated charcoal was studied as a function of adsorption time, amount of adsorbent, pH, concentration of adsorbates, sample volume and the oxidation states of the adsorbates. The cross-interference of the analytes was also investigated. Loaded filters were measured by energy-dispersive X-ray fluorescence spectrometry (EDXRF) and the amount of the unadsorbed analytes were determined by vapour generation atomic absorption spectrometry (VGAAS).     

Poly­[[tetra­aqua(μ7‐hydrogen di­chloro­methyl­enebis­phospho­nato)(μ5‐hydro­gen di­chloro­methyl­enebis­phosphon­ato)­tribarium(II)] monohydrate]

The title compound, {[Ba₃(CHCl₂O₆P₂)₂(H₂O)₄]·H₂O}_n or {[Ba₃(Cl₂CP₂O₆H)(H₂O)₄]·H₂O}_n, is two‐dimensional. The asymmetric unit contains three independent Ba²⁺ atoms, two chelating and bridging Cl₂CP₂O₆H³⁻ ligands and four aqua ligands, connected in layers parallel to the (100) plane. There are pores between the layers in the direction of the b axis filled with lattice water mol­ecules.     

Q value and half-lives for the double-β-decay nuclide 110Pd

The 110Pd double-β decay Q value was measured with the Penning-trap mass spectrometer ISOLTRAP to be Q=2017.85(64) keV. This value shifted by 14 keV compared with the literature value and is 17 times more precise, resulting in new phase-space factors for the two-neutrino and neutrinoless decay modes. In addition a new set of the relevant matrix elements has been calculated. The expected half-life of the two-neutrino mode was reevaluated as 1.5(6)×10(20) yr. With its high natural abundance, the new results reveal 110Pd to be an excellent candidate for double-β decay studies.     

Determination of phosphorus in waste water by EDXRF

Summary In a method developed for the determination of phosphorus in aqueous solutions, phosphorus was changed to the phosphate form, coprecipitated with hydrated iron(III) oxide, bound with activated charcoal and measured by EDXRF. The detection limit was 0.89 mg P/g activated charcoal. The method was used to determine the total phosphorus content of a waste water sample from a paper mill. Investigation of two sample destruction methods, dry ashing/HCl digestion and persulphate oxidation, showed the former to be more suitable for our purpose.     

Synthesis and structures of (3-methyl-2-pyridyl)diphenylphosphane derivatives of metal clusters

An unsymmetric bidentate ligand (3-methyl-2-pyridyl)diphenylphosphane (P(Mepy)Ph₂) is able to react with various tetranuclear transition metal clusters such as HRuCo₃(CO)₁₂, HRuRh₃(CO)₁₂ and Rh₄(CO)₁₂. The synthesis and crystal structures of HRuCo₃(CO)₁₀(P(Mepy)Ph₂) (1), HRuRh₃(CO)₁₀(P(Mepy)Ph₂) (2), RuRh₂(CO)₉(P(Mepy)Ph) (3) and Rh₆(CO)₁₄(P(Mepy)Ph₂) (4) are described. In 1, 2 and 4 the phosphane ligand replaces the carbonyls and acts as a bridging bidentate P-N group. The formation of 3 includes degradation of both the metal cluster core and the ligand itself. One of the P-C bonds in the ligand is cleaved and the ligand caps a metal triangle with a bridging phosphido group together with the nitrogen donor. The reaction between dinuclear Rh₂(CO)₄Cl₂ and P(Mepy)Ph₂ gives a binuclear Rh₂(μ-CO)Cl₂(P(Mepy)Ph₂)₂ (5) with bridging ligands in a head-to-tail arrangement. The crystal structure is also given.     

New practical synthesis of prazosin

A new four step synthesis of prazosin, 2-[4-(2-furoyl)piperazin-l-yl]-4-amino-6,7-dimethoxyquinazoline, has been described. The method is also adaptable for the preparation of other substituted 4-aminoquinazolines. The yields are good in every step and the reactions are performed with ease. Prazosin hydrochloride of high purity is obtained directly in the last step.