Determination of terbium and dysprosium by atomic absorption spectrometry

For the determination of terbium and dysprosium by atomic absorption spectrometry, the effects of several inorganic acids, metal ions and alcohols were studied. The two metals were determined in the presence of yttria and in rareearth oxides with satisfactory results.     

A new method for determining molecular masses of polyheteroarylenes

It is shown that the nondestructive ablation of polyheteroarylenes induced by submillimeter radiation of a free electron laser may be used to determine the molecular masses of polymers. The experimental procedure is described, and its results are compared with GPC data.     

A luminescence immunoassay test method for determining benzo[a]pyrene in natural water

A test method is developed for determining benzo[a]pyrene in natural water, based on the use of a polyethylene filter (frit) with adsorbed specific antibodies, placed within a transparent column. In passing a test solution, the analyte is adsorbed on the frit similarly to the process implemented in immunoaffinity preconcentration. The added conjugate of a labeled analyte takes the remained vacant binding sites of antibodies. Luminescent semiconductor nanoparticles (quantum dots) CdSe/ZnS, used as labels, enable visual determination under irradiation with UV light. The limit of detection for benzo[a]pyrene in water is ~0.5 ng/mL.     

A method for determining reactivity ratios in copolymerizations in the presence of a ceiling temperature effect

A novel kinetic treatment is proposed for the copolymerization of two monomers, M₁ and M₂, when M₂ has a low ceiling temperature. In the mechanism used, the growing copolymer with a terminal −M₂M₂· can undergo depropagation to −M₂· and M₂. If [M₁] ⪢ [M₂], as is possible experimentally when M₂ is radioactively labelled, a value of the reactivity ratio r₁ which is independent of the ceiling temperature effect can be obtained. This value is then used to obtain a value of the reactivity ratio r₂ which is also independent of the ceiling temperature effect. The derivation is valid provided that r₂ is small, which is often the case when M₂ has a low ceiling temperature. The method involves solution for r₂ by means of intersecting parabolas, each one representing a given monomer feed ratio and copolymer composition ratio.     

A new spectrophotometric method for determining the extraction constant of quaternary complexes

A new spectrophotometric method for determining the extraction constants of quaternary complexes is described. The method has been applied to a study of the distribution between water and toluene in the V(V)-salycylhydroxamic acid-nitrate-trioctyl methyl ammonium system, determining its conditional extraction constant in toluene for several pH values.     

Crystal structures and luminescence properties of two new terbium complexes with aromatic carboxylic acid

Two new terbium complexes with aromatic carboxylic acids, [(Tb)₂(L₁)₆(H₂O)₄] (1) and [(Tb)₂(L₂)₆(H₂O)₂(DMF)₂] (2) (HL₁: nicotinic acid; HL₂: 4-hydroxybenzoic acid), with different coordination geometries have been synthesized and their crystal structures determined. The luminescence properties of the two complexes, including the phosphorescence lifetime, have been investigated. The effect of a secondary ligand on luminescence of the ternary terbium complex with carboxylic acid and the relationship between luminescence properties and crystal structure, including coordination mode of the carboxyl groups from HL₁ and HL₂ and coordination mode of a secondary ligand, are discussed.     

Visible luminescence of dysprosium ions in oxyhalide lead borate glasses

Visible luminescence of Dy(3+) ions in oxyhalide lead borate glasses was examined. Luminescence spectra show two intense bands at 480 nm and 573 nm due to (4)F(9/2)→(6)H(15/2) (blue) and (4)F(9/2)→(6)H(13/2) (yellow) transitions of Dy(3+). Luminescence decays from (4)F(9/2) state and yellow-to-blue luminescence intensity ratios (Y/B) were analysed with PbX(2) (X=F, Cl) content. An introduction of PbX(2) to the borate glass results in the increasing of (4)F(9/2) lifetime and the decreasing of yellow-to-blue luminescence intensity ratio, which is due to reduction of covalency between Dy(3+) and O(2-)/X(-) ions.     

A new method for the direct precipitation of aluminium in the presence of iron

It is shown that aluminium can be precipitated as benzoate from solutions containing up to 1 gram of iron in the presence of thioglycollic acid, which reduces the iron and forms a soluble complex with ferrous iron. Very large amounts of such salts as ammonium chloride, sulphate and perchlorate, and sodium chloride do not interfere, nor do other divalent metals. Molybdates and tungstates are without effect, but chromium, vanadium and titanium interfere. This limits the direct application of the method in metallurgical analysis, but in many cases this speedy and complete separation will have many uses.     

Screening method for determining the presence of N-nitrosodiethanolamine in cosmetics by open-tubular capillary electrochromatography

The presence of the carcinogenic N-nitrosodiethanolamine (NDELA; CAS No. 1116-54-7) in cosmetic samples was determined using an etched, C18 modified capillary in the open-tubular capillary electrochromatography technique. A very simple extraction procedure leads to a sample matrix free from interferences. The calibration curve was created using UV detection at 214 nm. The detector response was linear in the range of 5-120 ppm total amount injected. Minimum detection limits (1 ppm NDELA injected on capillary) are suitable for screening a large number of cosmetic samples. Diethanolamine and triethanolamine precursors of nitrosamines are not detected at the wavelength used. Cosmetic samples were analyzed unspiked and after addition of 60 ppm of NDELA. In spiked samples recoveries varied from 94% (hand and body lotion) to 55% (lipstick sample). NDELA was found in unspiked samples of old (5-15 years old) cosmetics at concentrations of 14.0 ppm and 35.0 ppm.     

Azaxanthones and azathioxanthones are effective sensitisers for europium and terbium luminescence

Several azaxanthone and azathioxanthone sensitising chromophores have been incorporated into macrocyclic ligands and form well-defined Eu and Tb complexes in polar media. Excitation of the heterocyclic chromophore in the range 330 to 382 nm leads to modest amounts of aromatic fluorescence and relatively efficient metal-based luminescence, with absolute metal-based quantum yields of up to 24% in aqueous media.     

Effect of argon on the multibubble sonoluminescence of cerium,terbium, and dysprosium trichlorides

The ultrasonic (20 kHz) multibubble sonoluminescence spectra of aqueous air- or argon-saturated solutions of CeCl₃, TbCl₃, and DyCl₃ were obtained. Saturation with argon leads to the intensity redistribution in the spectrum of the continuum with an increase in its short-wavelength part and increases the intensity of the characteristic emission of Ce³⁺ and Tb³⁺ due to the enhancement of the sonophotoluminescence intensity, i.e., the re-emission of the absorbed part of the continuum by these ions. The Ce³⁺, Tb³⁺, and Dy³⁺ ions quench the OH* emission at 310 nm with a qualitative correlation between the degree of quenching and the standard redox potentials of the pairs Ln^IV/Ln^III. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1797–1802, September, 2008.     

A new method for determining droplet size distribution of an unstable dispersion

The droplet size distribution (DSD) of unstable water/oil dispersions has been studied with a new technique. The technique is based on a fast dilution of the dispersion injected into an analysis vessel where the DSD is analyzed with a video camera and a image analyzing tool. Dispersions generated with no pressure drop in the flow rig were compared to those generated with a pressure drop over a needle valve. The latter dispersion showed a much narrower DSD and a lower average droplet diameter. The results are from preliminary experiments in order to evaluate the method.     

Simultaneous electrodeposition behavior of dysprosium and terbium in 1-ethyl-3-methyl-imidazolium tetrafluoroborate ionic liquid

The simultaneous electrodeposition of dysprosium and terbium on platinum electrode in 1-ethyl-3-methyl-imidazolium tetrafluoroborate (EMIMBF₄) ionic liquid was investigated. The cyclic voltammetry, chronoamperometry and constant electrolysis experiments have been employed to examine the electrochemistry of dysprosium and terbium ions in 0.01 mol/L DyCl₃-0.023 mol/L TbCl₃-0.27 mol/L LiCl-EMIMBF₄ ionic liquid. The electrochemistry experiments indicated that the reduction of dysprosium and terbium ions in 0.01 mol/L DyCl₃-0.023 mol/L TbCl₃-0.27 mol/L LiCl-EMIMBF₄ ionic liquid was an irreversible process and simultaneous process. In 0.01 mol/L DyCl₃-0.023 mol/L TbCl₃-0.27 mol/L LiCl-EMIMBF₄ ionic liquid the diffusion coefficient of the diffusion process of species which controlled the total electrochemical reduction process have been determined to be (3.79–7.07) × 10⁻⁶ cm²/s from cyclic voltammetry and chronoamperometry results. XRD spectrum of constant electrolysis samples showed that dysprosium and terbium deposits were obtained.     

Simultaneous spectrofluorimetric determination of europium, dysprosium, gadolinium and terbium using chemometric methods

A spectrofluorimetric method for the simultaneous determination of dysprosium, europium, gadolinium and terbium in ternary and quaternary mixtures by the use of pyridine-2,6-dicarboxylic acid as a chelating agent was developed. The influence of chemical variables affecting the analytical reaction was evaluated. A partial least-squares procedure and PC Quant software were used to assess data obtained from a variable number of calibration solutions and wavelengths. The ensuing method was validated by applying it to the analysis of synthetic ternary (Eu-Dy-Tb) and quaternary mixtures (Eu-Dy-Gd-Tb) over the concentration ranges 60-550 mug Eu l(-1), 30-400 mug Dy l(-1) and 30-400 mug Tb l(-1) in the former, and 20-220 mug Eu l(-1), 20-235 mug Dy l(-1), 25-230 mug Gd l(-1) and 75-230 mug Tb l(-1) in the latter. The results obtained by using the two quantitation procedures are compared. The relative errors in the determinations were less than 8% in most cases.     

Molecular layering method used to sensitize luminescence from terbium(III) Oxide nanoparticles in porous glass

Possibility of obtaining nanoparticles of terbium(III) oxide in a porous glass by impregnating the support with an aqueous solution of TbCl₃ and subsequently calcining dried samples in air at 300°C was studied. The molecular layering method was used to modify the surface of encapsulated particles with titanium oxide layers of controlled thickness.     

Enhanced cell-killing action of cisplatin in the presence of terbium chloride

The literature indicates that the interaction of Tb³⁺ with DNA modified by the antitumour drug cis-diaminedichloroplatinum(II) (CDDP) results in substantial enhancement of the fluorescence of this cation, while no enhancement is observed in the case of DNA modified by irradiation with ionizing radiation. This study investigates the effect of Tb³⁺ on the survival of cultured mammalian cells treated with CDDP. HeLa cells were treated with a combination of^195mPt-CDDP and TbCl₃, and the relationship between lethal effect and the numbers of Tb and/or Pt atoms binding to DNA, RNA and proteins was examined. The Tb content in each fraction was determined using instrumental neutron activation analysis. It was found that the cytotoxic effect of CDDP was greatly enhanced by the presence of Tb ions (D₀ of CDDP fell from 8.3 μM without Tb to 3.2 μM with 0.75 mM Tb), while no such effect was found in radiation-induced cell-killing. The number of Tb atoms bound to DNA molecules in a cell was calculated to be about 4.5·10⁷, namely 1 per 1.400 nucleotides, under that situation.     

A new graphical method for determining stability constants of weak and polynuclear complexes

A graphical method is proposed for differentiating mono- and poly-nuclear complexes as well as for determining the stability constants of weak complexes. The method is based on the effect of dilution on the degree of dissociation of the complex. The precision for log K is ±0.02 for a degree of dissociation between 30 and 70%. The greatest values for log K that can be determined are 4.3, 12.4, 7.5 and 10.7 for 1:1, 2:2, 2:1 and 3:1 ligand: metal complexes, respectively. If log K₁ ? 5.7, the method permits log K₂ to be determined if simultaneous complexes are formed.