Emission-spectrometric determination of trace rare earth elements in europium oxide

Summary A dc arc excitation method in a controlled atmosphere was applied in the presence of CsCl-graphite (19) buffer for the quantitative determination of traces of rare earth elements in europium oxide. The intensities of the cyanogen band spectra and the background could be reduced by the use of argon-oxygen (41) mixed gas atmosphere and it was possible to obtain higher sensitivity than in the excitation in air. Addition of CsCl-graphite buffer causes an increase of the evaporation rate of the sample and of the number of atoms in the arc plasma, and the atoms and ions of rare earths distribute uniformly along the axis of the discharge gap. The buffer enhances the sensitivity and reproducibility and permits the determination of microquantities of 10 impurity elements within limits of detection from 3 to 11 ppm in high-purity europium oxide. The coefficients of variation are less than 13%.

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Emissionsspektrometrische Bestimmung von Spuren Seltener Erden in Europiumoxid

Zusammenfassung Die Anregung erfolgt im Gleichstrombogen in kontrollierter AtmosphÄre (Argon/Sauerstoff, 41) in Gegenwart eines CsCl-Graphit (19)-Puffers. Durch die Verwendung von Argon/Sauerstoff konnte die IntensitÄt des Untergrundes und der Cyanbanden erheblich reduziert und eine grö\ere Empfindlichkeit erreicht werden als bei der Anregung in Luft. Durch den Puffer wird die Verdampfungsgeschwindigkeit erhöht, die Anzahl der Atome im Bogenplasma vergrö\ert und eine gleichmÄ\ige Verteilung der Atome und Ionen lÄngs der Bogenachse erzielt. Empfindlichkeit und Reproduzierbarkeit werden verbessert. Spurenverunreinigungen von 10 Elementen können in hochreinem Europiumoxid bestimmt werden. Die Nachweisgrenzen liegen zwischen 3 und 11 ppm; der Variationskoeffizient ist < 13%.

     

Trace elements in water samples from Lake Nasser—Lake Nubia

Lake Nasser, one of the largest man made lakes in the world, is the reservoir created by the High Dam in the southermost part of Egypt and extends beyond Daal Cataract in the Sudan. The reservoir is about 480 kms long, of which, 300 kms are in Egypt (Lake Nasser) and 180 kms in the Sudan (Lake Nubia) and extends approximately within the latitudes of 21 N^o in the Sudan and 24 N^o in Egypt. In the west is the Great Western Desert and in the east the Eastern Desert of Egypt which extends up to the Red Sea. The deepest part is found near the High Dam (Lake Nasser) which reaches approximately about 86 metres. The depth decreases to the south and reaches approximately about 15 meters at Akasha in the Sudan. The Lake is much more wider in the egyptian part. The attached map shows the geographical locations of the lake from which the samples were collected. This work deals with the determination of 38 trace elements in water by neutron activation analysis (NAA). Also some parameters such as pH, (electric conductance), CO^2?, HCO ₃ ^? , CO₂, SO ₄ ^2? , residue (after evaporation), dissolved oxygen, NO ₂ ^? and temperature were determined in the field. The temperature ranged from 20.7–29.7°C, while the pH values from 7.45 to 9 (for the bottom and surface waters). The dissolved oxygen was determined and found to be 0.8–9.4 mg/l for bottom and surface waters, respectively.     

Distribution of the rare earth elements in sediments of the Northwestern Iberian Continental Shelf

The temporal and spatial distribution of the REEs was determined, by INAA, in sediment cores collected at Northern Iberian shelf along the area between the Finisterra Cape and the mouth of Minho river, to contribute to the understanding of the origin and sedimentation processes of sediments deposited at the Continental Shelf. The distribution pattern of the REEs were flat and similar to the shales. A negative Eu anomaly was found for all the sections of the analyzed cores. Significant positive correlations between the REE and Zr and Hf contents suggest that zircon is responsible for hosting both light and heavy REEs.     

珍珠中痕量稀土元素的ICP-MS测定及其分布特性

探讨了等离子体质谱(ICP-MS)分析珍珠样品中稀土元素的基体效应及多原子离子干扰,并采用干扰校正因子进行有效的校正,以In-Rh双内标校正体系进行分析信号动态漂移的监控和补偿,建立了珍珠样品中稀土元素的ICP-MS分析方法。方法的定量检出限为0．1～0．5ng／g,RSD≤15％(n=5)。所建立的方法用于标准物质Gui-1、Gui-2、Gui-3及人工养殖珍珠的分析。珍珠中稀土元素的分布与分馏特性与其生长环境密切相关。     

Preconcentration of trace transition metal and rare earth elements from highly saline solutions

Quantitative recovery and preconcentration of trace amounts of Ce(III), Co(III), Eu(III), Fe(III), Gd(III), Mn(II), Y(III) and Zn(II) ions from nearly saturated brines on the chelating resin Chelex-100 are described. Carrier-free radioactive isotopes were used. Only manganese was significantly affected by the high ionic strength of the brines. Chromium (III) was retained quantitatively by the resin but not eluted quantitatively. The results indicate that transition metal and rare earth ions can be quantitatively preconcentrated from solutions of low and high ionic strength.     

Enrichment method for trace amounts of rare earth elements using chemofiltration and XRF determination

A preconcentration method for subsequent determination of rare earth elements (REE) by X-ray fluorescence (XRF) spectrometry was developed. The method is based on using (o-[3,6-disulfo-2-hydroxy-1-naphthylazo]-benzenearsonic acid) (Thorin) as a complexing agent which is retained on a polyamide membrane by a chemofiltration process. The pH dependence of the chemofiltration of these metal ions on the membrane and other variables, such as flow-rate, contact time, kinetic of complex formation, etc. were determined. The membrane containing the chemofiltrate formed a thin film, which eliminated the interelemental effects when measured by XRF. The detection limits were 23, 23 and 49 ng/mL for Sm(III), Eu(III) and Gd(III), respectively. High enrichment factors were obtained. The method was successfully applied to the preconcentration of Sm(III), Eu(III) and Gd(III) from different samples. Received: 8 March 2000 / Revised: 9 May 2000 / Accepted: 15 May 2000     

Enrichment method for trace amounts of rare earth elements using chemofiltration and XRF determination

A preconcentration method for subsequent determination of rare earth elements (REE) by X-ray fluorescence (XRF) spectrometry was developed. The method is based on using (o-[3,6-disulfo-2-hydroxy-1-naphthylazo]-benzenearsonic acid) (Thorin) as a complexing agent which is retained on a polyamide membrane by a chemofiltration process. The pH dependence of the chemofiltration of these metal ions on the membrane and other variables, such as flow-rate, contact time, kinetic of complex formation, etc. were determined. The membrane containing the chemofiltrate formed a thin film, which eliminated the interelemental effects when measured by XRF. The detection limits were 23, 23 and 49 ng/mL for Sm(III), Eu(III) and Gd(III), respectively. High enrichment factors were obtained. The method was successfully applied to the preconcentration of Sm(III), Eu(III) and Gd(III) from different samples. Received: 8 March 2000 / Revised: 9 May 2000 / Accepted: 15 May 2000     

辉光放电质谱法测定稀土矿中的15种稀土元素

利用高纯铜粉与稀土矿石粉末均匀混合压片制样.混合15种高纯稀土氧化物制样建立标准工作曲线,校正15种稀土元素相对灵敏度因子,再进行定量分析.结果 表明,稀土元素工作曲线的线性方程相关系数R2均大于0.996,相对标准偏差(RSD)小于5％,满足定量分析要求.测定结果与电感耦合等离子体质谱法(ICP-MS)和电感耦合等离...     

Applicability of capillary electrophoresis to the analysis of trace rare earth elements in geological samples.

This study developed a methodology to analyze trace rare earth elements (REEs) in geological materials by capillary electrophoresis (CE). Changed from dilute HNO3 into a water medium by heating, REE ions are detectable at approximately 2 ng mL(-1). In the presence of coexisting elements from geological samples, REE separations were carried out. After sample fusion with Na2O2 and interference separation with ammonium pyrrolidinedithiocarbamate chelate, REE analytes were coprecipitated with Mg(OH)2 at pH 8.5, and then prepared into a water medium for CE determination. Using the standard addition method, this protocol was validated by analyses with better than 5% precision. This method was applied to geological materials; the REE results are in consistence with their certified values. With electrokinetic injection, internal standard (IS) selected among lanthanides is a prerequisite of high-quality REE data. An approach was proposed to derive the IS content for further correcting its contribution from unknown samples.     

Production oriented method for the determination of rare earth and other trace elements in rocks by ICP-MS

The rare earth elements along with Y, Sc, Co, Hf, Nb, Rb, Ta, Th, Ti, U, V and Zr have been determined in ten standard reference materials and ten granitoid samples by inductively coupled plasma mass spectrometry (ICP-MS). Two digestion methods have been used: (a) dissolution with hydrofluoric-perchloric acid followed by fusion of the residue with lithium metaborate, (b) dissolution with hydrofluoric acid-perchloric acid followed by fusion with lithium metaboratesodium perborate and addition of hydrogen peroxide. An evaluation of the two decomposition methods and a comparison of the ICP-MS and X-ray fluorescence results have been carried out. In comparing the two digestion methods, method (b) gave more accurate results for Nb and Ta, and it has been applied to a rock geochemistry project covering whole Finland (about 7000 samples). The statistical stability of the method has been monitored by frequent analyses of reference material SDC-1 (Mica Schist, USGS).     

Sorption in the chemistry of rare earth elements

Sorption methods for the concentration and separation of rare earth elements are reviewed. Sorbents based on organic polymers, specifically strongly and weakly acidic cation exchangers, anion exchangers, and complexing sorbents, are successively considered. Data on the use of inorganic sorbents and solid phase extractants in the rare earth chemistry are also given. Considerable attention is paid to hybrid organomineral materials constituting a promising class of sorbents. Advantages and disadvantages of using biosorbents, molecularly imprinted sorbents, and nanosorbents for the concentration and separation of rare earths are discussed.     

Production oriented method for the determination of rare earth and other trace elements in rocks by ICP-MS

The rare earth elements along with Y, Sc, Co, Hf, Nb, Rb, Ta, Th, Ti, U, V and Zr have been determined in ten standard reference materials and ten granitoid samples by inductively coupled plasma mass spectrometry (ICP-MS). Two digestion methods have been used: (a) dissolution with hydrofluoric-perchloric acid followed by fusion of the residue with lithium metaborate, (b) dissolution with hydrofluoric acid-perchloric acid followed by fusion with lithium metaboratesodium perborate and addition of hydrogen peroxide. An evaluation of the two decomposition methods and a comparison of the ICP-MS and X-ray fluorescence results have been carried out. In comparing the two digestion methods, method (b) gave more accurate results for Nb and Ta, and it has been applied to a rock geochemistry project covering whole Finland (about 7000 samples). The statistical stability of the method has been monitored by frequent analyses of reference material SDC-1 (Mica Schist, USGS).     

Distribution of rare earth elements in the estuarine and coastal sediments of the Daliao River System, China

The Daliao River System (DRS) estuary in Liaodong Bay features a highly industrial, urbanized, and agricultural catchment. The objective of this study was to determine the content, behavior, and distribution of the rare earth elements (REEs) in the estuarine and coastal sediments. To this end, 35 sediment samples were collected from the estuarine and coastal area and analyzed for REEs, Fe, Al, and Mn. The mean concentrations in mg kg^?1 of the sediments were 33.4 (La), 64.1 (Ce), 7.9 (Pr), 29.0 (Nd), 5.4 (Sm), 1.2 (Eu), 4.2 (Gd), 0.78 (Tb), 4.0 (Dy), 0.84 (Ho), 2.3 (Er), 0.40 (Tm), 2.3 (Yb), and 0.37 (Lu). The REE concentrations in the sediments were significantly correlated with one another (r ²  = 0.959–0.988) and the concentrations of Fe, Al, and Mn (r ²  = 0.768–0.870). The total concentration ∑REE ranged from 73.5 to 203.5 mg kg^?1, with an average of 156.0 mg kg^?1 being observed, and generally higher in the estuarine sediments than in the coastal sediments, most likely due to the salt-induced coagulation of river colloids and subsequently their accumulation at the estuarine bottom. The ratio of light REEs (∑LREE) to heavy REEs (∑HREE) was 9.4. Chondrite-normalized REE distributions were observed to be similar for the estuarine and coastal sediments, riverine suspended particles, and watershed soils of the DRS with higher LRRE enrichment than HREE and greater Eu depletion than Ce depletion. These results demonstrate that neither geochemical processes that carry soils to estuarine sediments nor long-term industrial and agricultural activities alter the distribution or fractionation of the REEs in the study area.     

Polyphenylcyclopentadienyl complexes of rare earth elements

Reaction of LnCl₃(thf) _x (Ln = Y, La, Yb, Lu) with NaCp^Phn (Cp^Phn = 1,3-Ph₂C₅H₃, 1,2,4-Ph₃C₅H₂, Ph₄C₅H) leads to formation of monocyclopentadienyl dichloride complexes Yb(Ph₂C₅H₃)Cl₂(thf)₃ (1), Ln(Ph₃C₅H₂)Cl₂(thf)₃ (Ln = Y (2), Lu (3)), La(Ph₄C₅H)Cl₂(thf)₃ (4). Molecular structures of 1, 2 and the polynuclear complex [(Ph₃C₅H₂)₃Lu₄(Cl)₇(O)(thf)₃] (5), which is a partial hydrolysis product of 3, have been established by the X-ray method.     

Energy-adjusted pseudopotentials for the rare earth elements

Nonrelativistic and quasirelativistic energy-adjusted pseudopotentials and optimized (7s6p5d)/[5s4p3d]-GTO valence basis sets for use in molecular calculations for fixed f-subconfigurations of the rare earth elements, La through Lu, have been generated. Atomic excitation and ionization energies from numerical HF, as well as SCF pseudopotential calculations using the derived basis sets, differ by less than 0.1 eV from numerical HF all-electron results. Corresponding values obtained from CI(SD), CEPA-1, as well as density functional calculations using the quasirelativistic pseudopotentials, are in reasonable agreement with experimental data.