Simultaneous determination of trace metals by solid phase absorptiometry: application to flow analysis of some rare earths

Solid phase absorptiometry was applied to the simultaneous flow analysis of trace metals in combination with a micro black flow-through cell packed with ion exchanger beads and a multi-channel photodetector connected with optical fibers. A 4.0 cm³ sample solution containing five rare earth metal ions (Dy, Ho, Tm, Er and Nd) was introduced into a flow system and these metal ions were concentrated on a cation exchanger (Muromac 50W-X4) in a flow-through cell. The absorbance increases originating from the f-f or d-f transition bands of these metal ions were directly and continuously measured at 910 nm for Dy, at 530 nm for Ho, at 683 nm for Tm, 522 nm for Er and at 790 nm for Nd, respectively. A multi-variable analysis method was combined with the flow analysis because the absorption spectra of the five rare earth metal ions partly overlapped one another. Although no coloring reagents were used, the proposed method was about ?200 times more sensitive than the corresponding solution method. The reproducibility of this method was less than ± 5%. The detection limits were 0.03, 0.40, 0.30, 0.35 and 0.23 mg dm^–3 for Dy, Ho, Tm, Er and Nd, respectively. Five rare earth metal ions could be precisely determined in practical samples such as yttrium concentrate. Received: 14 March 2000 / Revised: 24 May 2000 / Accepted: 28 May 2000     

交流电弧中共存稀土元素对光谱线强度影响的研究

本工作较系统地研究了在交流电弧中不同量的共存稀土元素镝、钬，饵，铥和镱对某些被测稀土元素光谱线强度的影响。用交流电弧激发溶液干渣样品，其样品是在固定量的被测元素溶液中各自分别加入不同量的共存元素镝、钬、铒、铥和镱，摄谱后测量各被测元素的光谱线强度对共存元素在溶液中各个不同浓度作关系曲线。     

The solubilities and anion-exchange behavior of rare earth elements in potassium carbonate solutions

The solubilities of rare earth elements (La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er,Tm, Yb,Lu andY) in potassium carbonate solution, and the distribution coefficients of the rare earth ions between the carbonate solution and Dowex I resin were measured. The values obtained show a variation that depends on the concentration of potassium carbonate and atomic number. There is a clearly different tendency in these values between La-Ho and Er-Lu.     

稀土丙酸盐的红外光谱研究

本文研究了La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y十三种稀土丙酸盐的FT-IR光谱, 对1800-100cm^-^1的主要红外吸收谱带进行了归属, 指认316-349cm^-^1的强吸收带为Ln-O键的伸缩振动带. 稀土丙酸盐红外光谱表明存在两种不同的羧基配位形式. 从La到Tm以及Y等十一种丙酸配合物的配位羧基具有对称的螯合双齿形式, 而对稀土Yb和Lu, 与中心离子配位的三个羧基中, 至少有一个羧基具有螯合桥式三齿配位形式. 结果还表明稀土丙酸盐Ln-O键基本上是离子键.     

电感耦合等离子体质谱分析莲子芯茶中的稀土元素

建立了一种压力密闭消解电感耦合等离子体质谱法测定莲子芯茶中Y、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu等15种稀土元素的方法。用该方法分析国家标准物质中的稀土元素,分析结果与标准值一致,并用该方法对莲子芯茶实际样品进行了分析。     

稀土取代的复合氧化物Eu_（0．5）RE_（0．5）Fe_（0．5）Mn_（0．

利用固相反应合成了稀土取代的复合氧化物Ｅｕ_（０．５）ＲＥ_（０．５）Ｆｅ_（０．５）Ｍｎ_（０．５）Ｏ_３（ＲＥ＝Ｌａ，Ｐｒ，Ｎｄ，Ｓｍ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ）．测量了这些化合物的ＸＲＤ和ＸＰＳ谱。在ＸＰＳ研究中发现，稀土取代而使稀土元素本身的结合能相对于其倍半氧化物中的有所降低；在取代的复合氧化物中，随着ＲＥ离子半径的减小，Ｆｅ、Ｍｎ的结合能随之增加。     

Lumineszenz und sensibilisierte Emission der dreiwertigen Seltenen Erden in Sr3La2W2O12

By activation of the new host lattice Sr₃La₂W₂O₁₂ with the trivalent rare earth ions Nd, Eu, Ho, Er, Tm, Yb an intense emission in the visible and/or infrared region is obtained. Energy transfer from Er³⁺ to Tm³⁺ and Nd³⁺ to Yb³⁺ has been found to occur. The excitation, emission, and diffuse reflectance spectra are analyzed for Sr₃La₂W₂O₁₂: Ln³⁺ (Ln = Nd, Sm, Eu, Dy, Ho, Er, Tm, Yb).     

ICP-发射光谱测定镁钇合金中稀土和非稀土元素

本文研究了ICP-AES测定镁钇合金中17种稀土和非稀土元素的方法。选择了合适的分析线及ICP操作参数。探讨了酸度,载气和基体的变化对被测元素谱线强度的影响,不用化学分离,可同时测定镁钇合金中Y,La,Ce,Pr,Nd,Gd,Tm, Dy,Lu,Ho,Er,Yb和Mo,Ni,Cu,Al,Fe。测定范围分别为(％):Y_(1-40);La,Er0.048—3.2;Tm,Yb,Lu,Dy0.019—1.28;Ho0.0384—2.56;Ce0.0288—1.92;Fe,Ni,Mo,Al,Pr,Nd,Gd0.024-1.6;Cu0.012—0.8。相对标准偏差为1.1—5.3％。回收率为90～115％。方法简单、快速、再现性好、准确度高。     

Application of atomic absorption spectrophotometry for the determination of lanthanides in ores and rare earth concentrates

Summary Concentrations of La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Y were determined in rare earth ores and concentrates by the flame atomic absorption method, those of Eu, Gd, Dy, Ho, Er, Tm, Yb and Y also by the flameless method with a graphite cell. Accuracy was checked by using a standard lanthanides mixture. The results of the determinations in concentrates (by flame and by furnace AAS, both direct measurement and standard addition method) were compared with those obtained by spectrophotometry. Detection limits were defined in a HGA-70 graphite cell with application of a standard graphite tube. The results of the examinations revealed that both the AAS methods are suitable for lanthanide determinations in the above materials. Heavy lanthanides can be determined in lower concentrations than by spectrophotometry.

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Anwendung der Atomabsorptions-Spektralphotometrie zur Bestimmung von Lanthaniden in Erzen und Seltenerd-Konzentraten

Zusammenfassung La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb und Y wurden in Erzen und Konzentraten mit Hilfe der Flammen-Atomabsorptionsspektrometrie bestimmt, Eu, Gd, Dy, Ho, Er, Tm, Yb und Y auch nach der flammenlosen Methode unter Anwendung der Graphitküvette. Die Genauigkeit wurde mit Hilfe einer Standardmischung von Lanthaniden geprüft. Die Ergebnisse der Bestimmungen in Konzentraten (Flammen- und flammenlose AAS, Direktmessung und Methode der Standardzugaben) wurden mit spektralphotometrischen Resultaten verglichen. Die Nachweisgrenzen wurden für die Graphitküvette HGA-70 mit Standardgraphitröhre bestimmt. Es ergab sich, daß beide AAS-Methoden für den genannten Zweck verwendbar sind. Die schweren Lanthanide können in niedrigeren Konzentrationen bestimmt werden als mit Hilfe der Spektralphotometrie.

     

An XPS Study of Perovskite Oxides RECr03

Perovskite Oxides RECr0₃ (RE=La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb) were prepared by the means of solid state reaction.The measurments of XRD and XPS showed that the replacement by rare earth element lowers the binding energy(BE) of rare earth ions, compared with their sesquioxides. In the Perovskite Oxides, the BE of Cr2p_3/2 increases with the decrease of ionic radius of the RE ion.The reason for the changes of BE are discussed.     

ICP-MS法测定土壤中十五种稀土元素

采用微波消化土壤样品,通过优化等离子体功率、雾化器流量等仪器参数,找出最佳的测定条件,直接测定了土壤中Y、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu15种稀土元素含量。结果表明,各个元素的方法检出限为0．004—0．024ng／mL,样品的检出下限为0．09—0．30ng／mL,结果较为满意。     

一类新型含铁的希土化合物

合成了九个新的含铁希土化合物LnFe(CN)_2(CONH_2)_4。通过元素分析、红外光谱对它们进行了表征。化合物的~(57)Fe穆斯堡尔参数表明,化合物中铁处于三价低自旋志,有从铁向希土的电子转移作用。     

稀土(III)-冠醚配位反应的热力学性质I:稀土(III)高氯酸盐与苯-15-冠-5-在乙腈溶液中配位反应的量热滴定研究

用量热滴定法于298.15K测定了除钪、钷以外的全部十五种稀土(III)高氯酸盐与苯并-15-冠-5在乙腈溶液中的配位作用。借助计算机算出了配合物的稳定常数和配位焓, 进而算出了配位自由能和配位熵。结果表明:十五种稀土(III)离子与苯并-15-冠-5都可以配位, 配位焓为正值;La^3^+配合物最稳定, Ce^3^+次之, 其余稀土(III)离子配合物稳定性变小, 但彼此差别不大, 在Tb处有突变;熵在配合物形成时起稳定化作用。     

Raman scattering in rare earths tetraborides

The Raman spectra of single crystalline RE (rare earth) tetraborides REB₄ (RE = Y, La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Lu) are measured and analysed with respect to the dependence of the phonon frequencies on the rare earth metal. Phonons representing octahedral B₆ units are identified by comparison to the according phonon modes of hexaborides. Their relative force parameters are estimated.     

Rare‐Earth Oxide Nanostructures: Rules of Rare‐Earth Nitrate Thermolysis in Octadecylamine

The decomposed regularity of rare‐earth nitrates in octadecylamine (ODA) is discussed. The experimental results show that these nitrates can be divided into four types. For rare‐earth nitrates with larger RE³⁺ ions (RE=rare earth, La, Pr, Nd, Sm, Eu, Gd), the decomposed products exhibited platelike nanostructures. For those with smaller RE³⁺ ions (RE=Y, Dy, Ho, Er, Tm, Yb), the decomposed products exhibited beltlike nanostructures. For terbium nitrate with a middle RE³⁺ ion, the decomposed product exhibited a rodlike nanostructure. The corresponding rare‐earth oxides, with the same morphologies as their precursors, could be obtained when these decomposed products were calcined. For cerium nitrate, which showed the greatest differences, flowerlike cerium oxide could be obtained directly from decomposition of the nitrate without further calcination. This regularity is explained on the basis of the lanthanide contraction. Owing to their differences in electron configuration, ionic radius, and crystal structure, such a nitrate family therefore shows different thermolysis properties. In addition, the potential application of these as‐obtained rare‐earth oxides as catalysts and luminescent materials was investigated. The advantages of this method for rare‐earth oxides includes simplicity, high yield, low cost, and ease of scale‐up, which are of great importance for their industrial applications.     

Extraction of rare-earth,yttrium, and scandium perchlorates by podands bearing diphenylphosphorylacetamide terminal groups

Partition of trace amounts of metal (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc) perchlorates was studied between aqueous HClO₄ solutions and dichloroethane solutions of phosphorus podands bearing two Ph₂P(O)CH₂C(O)NH-terminal groups linked via di-and triethylene glycol spacers. The stoichiometry of extracted complexes was determined. The efficiency of metal ion recovery to the organic phase was studied as a function of aqueous HClO₄ concentration and nature of the organic solvent. The compounds synthesized have higher metal extraction capacities in HClO₄ solutions than (dibutylcarbamoyl)diphenylphoshine oxide. The utility of macroporous polymer sorbents impregnated by these podands for extracting and concentrating rare earth(III) and scandium(III) ions from aqueous perchlorate solutions was demonstrated.     

On the potentially excellent reducing ability of a series of low-valent rare earths induced by photoirradiation

Mixed systems of a series of rare earth metals such as La, Ce, Pr, Nd, Sm, Eu, and Yb and their low-valent rare earth diiodides exhibit excellent reducing ability toward the reductive deiodation from 1-iodododecane as a model compound compared with their single systems. More importantly, under photoirradiation conditions, the C-I bond reduction using ‘Ln/LnI₂’ takes place efficiently in refluxing THF, even in the cases of heavy rare earths such as Gd, Tb, Dy, Ho, Er, and Tm.     

Determination of rare earth elements in seawater by inductively coupled plasma mass spectrometry with off-line column preconcentration using 2,6-diacetylpyridine functionalized Amberlite XAD-4

An off-line column preconcentration technique using a micro-column of 2,6 diacetylpyridine functionalized Amberlite XAD-4 with inductively coupled plasma mass spectrometry (ICP-MS) as a means of detection has been developed. The aim of the method was to determine rare earth elements (REEs) (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in seawater. Sample solutions (2–10 mL) were passed through the column which was then washed with ultra-pure water to remove residual matrix. The adsorbed cations on the resin were eluted by using 2 mL of 0.1 mol L⁻¹ HNO₃ containing 10 ng mL⁻¹ indium as an internal standard. The eluent was analyzed for the metal concentrations using ICP-MS. Sample pH as well as the sample and eluent flow rates were optimized. The sorption capacity of resin was determined by the batch process, by equilibrating 0.05 g of the resin with solutions of 50 mL of 25 mg L⁻¹ of individual metal ions for 4 h at pH 6.0 at 26 °C. The sorption capacities for the resin were found to range between 47.3 μmol g⁻¹ (for Lu) and 136.7 μmol g⁻¹ (for Gd). Limits of detection (3σ), without any preconcentration, ranged from 2 ng L⁻¹ to 10.3 ng L⁻¹ (for Tm and Lu respectively). The proposed method was applied to the determination of REEs in seawater and tap water samples.     

1H and13C NMR studies on lanthanide complexes with proline and hydroxyproline

The formation and the mode of coordination of rare earth (Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu) complexes with proline and hydroxyproline have been investigated by¹H and¹³C NMR spectral techniques. It has been established that the nitrogen and the carboxyl group of the ligands are involved in complexation, and that the OH^– group of hydroxyproline does not participate in coordination.

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¹H und¹³C NMR Untersuchungen an Lanthanid-Komplexen mit Prolin und Hydroxyprolin

Zusammenfassung Die Bildung und die Koordination von seltenen Erden (Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu) in Komplexen mit Prolin und Hydroxyprolin wurden mit Hilfe von¹H- und¹³C-NMR-Spektroskopie untersucht. Es wurde festgestellt, daß in den Komplexen der Stickstoff und der Carboxylsauerstoff der Liganden koordinieren. Die OH^–-Gruppe von Hydroxyprolin nimmt keinen Anteil an der Koordinierung.

     

噻吩甲酰三氟丙酮稀土螯合物的红外光谱

稀土β-二酮络合物被用作激光材料和核磁位移试剂已进行了广泛的研究^[1]。根据红外光谱峰值、强度和力常数可讨论配位键性质^[2]。对某些(TTA)₃M类型稀土螯合物的红外光谱虽已见报导^[3,4],但对四个双齿配位体与稀土元素螫合成络合物的红外光谱却研究甚少^[5]。