[en] A new system using a polarographic adsorptive wave for determining trace scandium was proposed. In 0.2 mol/L NH₄OAc, the Sc(III)-ACBK [1,8-dihydroxy-2-(2-hydroxy-5-sulfo-1-phenylazo)-3,6-disulfo-naphthalene, called acid chrome blue K] complex emerged a sensitive adsorptive complex wave (Ep' = -0.67V). The molar ratio of Sc(III) to ACBK in the complex was established as 1:2 and the apparent stability constant β₂ = 2.7 x 10¹⁵. But for Y(III), the molar ratio was 1:1 and β=1.5 x 10⁵. Because of the particularity of Sc complex, the sensitivity and the selectivity of determination Sc is much better than that of other rare earth ions. The detection limits is 1.1 x 10^-7 mol/L for oscillopolarography and 2.0 x 10^-8 mol/L for adsorptive stripping voltammetry

[en] Gas chromatography and pattern recognition methods were used to develop a potential method for typing jet fuels so a spill sample in the environment can be traced to its source. The test data consisted of 256 gas chromatograms of neat jet fuels. 31 fuels that have undergone weathering in a subsurface environment were correctly identified by type using discriminants developed from the gas chromatograms of the neat jet fuels. Coalescing poorly resolved peaks, which occurred during preprocessing, diminished the resolution and hence information content of the GC profiles. Nevertheless a genetic algorithm was able to extract enough information from these profiles to correctly classify the chromatograms of weathered fuels. This suggests that cheaper and simpler GC instruments ca be used to type jet fuels

[en] A new reagent isopropyl-3-pentadecylphenyl phosphoric acid (IPPA = HR) was synthesized from cardanol [I-37, 300-39-5] and was used to investigate the extraction behavior of lanthanum(III), europium(III) and lutetium(III) from HCl and HClO₄ solutions into toluene. The species extracted were found to be Ln(HR₂)₃ (where Ln = La(III) or Eu(III) or Lu(III)). The extraction behavior of above lanthanides has also been compared with yttrium and other rare earths. It was observed that the extraction increases with increase of atomic number of rare earths. In addition the extraction efficiency of IPPA has been compared with well known acidic organophosphorus extractants like di-2-ethylhexyl phosphoric acid (DEHPA) and 2-ethylhexyl-mono-2-ethylhexyl phosphoric acid (EHEHPA). 6 refs., 5 figs., 3 tabs

[en] Niobium is separated from Ta and V by elution with 0.5 M HF in a column of chelating resin containing N-benzoyl-N-phenyl-hydroxylamine (NBPHA) as a function group. Niobium and tantalum can also be separated using their differential distribution coefficient and elution behavior, monitored by radiometric and also be spectrophotometric methods. 15 refs., 1 fig., 2 tabs

[en] A solvent extraction-spectrophotometric determination of trace amounts of ruthenium has been developed, based on the formation of an ion association complex of ruthenium (III) with 2,4,6-tris(2'-pyridyl)-1,3,5-triazine as primary ligand and picrate as counter-ion; this complex is then extracted into 1,2-dichloroethane. The complex is formed at pH 2.0-7.0, upon heating at 90 C for 60 min, and the ruthenium concentration can be determined by measuring the absorbance directly in the organic phase. Beer's law is obeyed over the concentration range 1.0-10.0 μg ml^-1 corresponding to 0.050-0.500 μg ml^-1 of ruthenium in the aqueous solution. The apparent molar absorptivity and the Sandell's sensitivity were found to be 3.4 · 10⁵ 1 mol^-1 cm^-1 and 0.30 ng cm^-2, respectively. The interference of various ions was examined and the serious interferences from iron and other metals of the VIII group were minimized by employing the derivative spectrophotometric technique in conjunction with appropriate masking agents

[en] The composition, stability constants and molar absorption coefficients of the chelates of thulium, ytterbium, lutetium and thorium ions with Semi-xylenol Orange (SXO) are determined spectrophotometrically in a medium of hexamine, and chloroacetate buffer. In the thulium, ytterbium, lutetium and thorium-Semi-xylenol Orange systems, Tm(SXO), Yb(SXO), Lu(SXO) and Th(SXO) chelates are formed with logarithmic overall stability constants of 12.48 ± 0.01, 12.55 ± 0.01, 12.94 ± 0.015 and 22.16 ± 0.01 and molar absorption coefficients of 2.22 x 10⁴ (530 nm), 2.17 x 10⁴ (532 nm), 2.25 x 10⁴ (530 nm) and 3.33 x 10⁴ (535 nm) dm³ mol^-1 cm^-1 respectively. The precision and accuracy attainable in direct spectrophotometric titrations of the Tm³⁺, Tb³⁺, Lu³⁺ and Th⁴⁺ separately and the successive determination of each of the three rare earths and Th⁴⁺ ion with a 0.001 mol dm^-3 solutions of diethylenetriaminepentaacetic acid (DTPA) and PbCl₂ of the same concentration using Semi-xylenol Orange (SXO) as a metallochromic indicator have been studied. Spectrophotometric determination of Tm³⁺, Tb³⁺, Lu³⁺ and Th⁴⁺ individually using SXO at the optimum conditions of maximum color development have been carried out. Thorium has been determined spectrophotometrically in three different artificial samples with lutetium similar to those of monazite mineral. Ytterbium (III) has been determined in three different laboratory synthesized samples with Ca²⁺ and Fe³⁺ similar to those of euxenite mineral which occurs in nature and the results were reproducible and satisfactory

[en] The stability constants of the complexes between a series of lanthanide(III), UO₂(II), Cu(II), Ni(II) and Co(II) cations and p-, m- and o-HDMPP ions have been measured using potentiometric methods. The formation constants for o-HDMPP is larger than those for m- and p-HDMPP. The results are explained in terms of the differences in the dentate character of these ligands. The coordination sites on o-HDMPP are inferred through the study of infrared spectra, elemental analysis and conductance for o-HDMPP-Cu(II) chelate. 31 refs., 4 figs., 2 tabs

[en] The authors achieved 42% counting efficiency for ⁹²P dried onto nitrocellulose filters using an end window Geiger detector and fixed geometry. This efficiency is greater than those previously reported. The counting efficiency was improved by using a high atomic number backing metal on which the filter is mounted

[en] The composition, stability constants and molar absorption coefficient of the chelate of thorium ion with Semimethylthymol Blue, SMTB is determined spectrophotometrically in a medium of perchloric acid and sodium perchlorate solution (pH 2.0). In the thorium-SMTB system, a purple red Th(SMTB) chelate is formed with logarithmic overall stability constant of 20.76±0.01 and molar absorption coefficient of 1.44x10⁴ (560 nm) dm³ mol^-1 cm^-1. SMTB was proposed as a new reagent for the spectrophotometric determination of micro-molar amounts of thorium at λ_max 560 nm. The colour development depends on time, temperature, pH and buffer species. The interferences of different anions, cations and organic acids on thorium determination were also investigated. Beer's law was obeyed for 11.6-104.4 μg Th(IV)/25 ml(0.46-4.18 ppm). SMTB was used for the spectrophotometric determination of thorium in medium and low-grade minerals and ores and the results were reproducible and satisfactory. Comparative study including different statistical tests between the spectrophotometric and complexometric determinations of thorium in its minerals and ores using SMTB has been carried out

[en] In this paper the absorption spectra of 4f electron transitions of the systems of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid and diethylamine have been studied by normal and third-derivative spectrophotometry. Their molar absorptivities are 80 1.mol^-1.cm^-1 for neodymium and 65 1.mol^-1.cm^-1 for erbium. Use of the third-derivative spectra, eliminates the interference by other rare earths and increases the sensitivity for Nd and Er. The derivative molar absorptivities are 390 1.mol^-1.cm^-1 for Nd and 367 1.mol^-1.cm^-1 for Er. The calibration graphs were linear up to 11.8 μg/ml of Nd and 12.3 μg/ml of Er, respectively. The relative standard deviations evaluated from eleven independent determinations of 7.2 μg/ml (for Nd) and 8.3 μg/ml (for Er) are 1.3% and 1.4%, respectively. The detection limits are 0.2 μg/ml for Nd and 0.3 μg/ml for Er. The method has been developed for determining those two elements in mixture of lanthanides by means of the third-derivative spectra and the analytical results obtained are satisfactory