Multiple ionization effects on total L-shell X-ray production cross sections by proton impact

The effect of multiple ionization on total L-shell X-ray production cross sections by proton impact, with energies below 1 MeV, on elements with atomic numbers in the range 26–55 was studied. Measurements of those cross sections for several elements were also done to enlarge the experimental database. Several tables for atomic parameters (fluorescence yields and Coster–Kronig transition probabilities) were used. The agreement between theory and experiment was optimized when average fluorescence yields given by Hubbel et al. (J. Phys. Chem. Ref. Data 23(2) (1994) 339) and a multiple ionization model proposed by Lapicki et al. (Phys. Rev. A 34(5) (1986) 5813) were used together. Thus, improvements to theoretical predictions for ionization cross sections should consider first a correct set of atomic parameters.     

Determination of rare earth elements by radioisotope induced X-ray emission spectroscopy

A ring-shaped, 10⁹ Bq²⁴¹Am radioisotope source was used for the excitation of K-shell X-rays from rare earth elements (56<Z<64), present in powdered geological material. In order to improve the efficiency of the measurement of these elements in the concentration range down to 10 ppm, the optimum geometry of the system was found. The results obtained are presented and discussed.     

Determination of rare earth elements in Yttrium oxide by secondary ion mass spectrometry

Summary Rare earth elements (REEs) in yttrium oxide were determined by secondary ion mass spectrometry (SIMS) with high sensitivity. The calibration graph approach was employed with chemically prepared standards. Molecular ion interferences derived from the matrix components which limit the superior sensitivity of SIMS were successfully suppressed by an energy filtering technique. The detection limits of the elements ranged from 0.02 to 0.2 g·g^-1.     

Separation of rare earth elements from uranium by solvent extraction and ion exchange

The detection limit of⁹⁹Tc in (,) radio-activation analysis was determined in the presence of molybdenum and compared with that of⁹⁹Tc in pure materials in the previous paper. The isotopic ratio of molybdenum in a⁹⁹Mo–^99mTc generator column could be simultaneously determined by photon activation analysis.     

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...     

离子色谱非梯度洗脱法同时测定7种稀土元素的研究

研究了离子色谱非梯度洗脱法同时测定7种稀土元素的方法,用草酸一元淋洗液,采用非梯度洗脱方式,以PAR为显色荆,在520nm处对7种稀土元素同时进行检测。考察了淋洗液的组成、浓度、pH及流量等因素对被测组分分离和测定的影响,选择了显色剂的浓度、流量和检测波长,并进行了干扰实验,在选定的最佳分离测定条件下,测定了7种稀土元素的线性回归方程、检出限0．04～0．20mg／L,回收率在94．3％～101．5％之间。本方法已用于稀土氧化物的高温氯化产物中稀土元素的测定。     

L X-ray production cross sections, average L shell fluorescence yield and intensity ratios in heavy elements

L X-ray fluorescence cross sections, and intensity ratios were measured for elements in the 70￡Z￡92 atomic range at the excitation energy 59.5 keV using a Si(Li) detector. Furthermore, L X-ray fluorescence cross sections and intensity ratios were calculated for elements in the same range. The average L shell fluorescence yields were derived using experimental L X-ray fluorescence cross sections and theoretical photoionization cross sections. The obtained results were compared with other experimental and theoretical values. This revised version was published online in August 2006 with corrections to the Cover Date.     

Selective accumulation of light or heavy rare earth elements using gram-positive bacteria

The accumulation of samarium from a solution only containing samarium by Arthrobacter nicotianae was examined. The amount of accumulated samarium was strongly affected by the concentration of samarium and pH of the solution. The accumulation of samarium by the strain was very rapid and reached equilibrium within 3 h. The accumulation of samarium-europium or europium-gadolinium from the solution containing the two metals using various actinomycetes and gram-positive bacteria was also examined. Most of the tested strains could accumulate similar amounts of samarium and europium; however, most of the tested strains could accumulate a greater amount of europium than gadolinium. Especially, the amounts of accumulated europium using gram-positive bacteria were higher than those using actinomycetes. The selective accumulations of light or heavy rare earth elements (REEs) using A. nicotianae and Streptomyces albus were also examined. The amounts of accumulated samarium and europium were higher than those of the other light REEs using both microorganisms. S. albus can accumulate greater lutetium than other REEs from a solution containing yttrium and eight heavy REEs. On the other hand, A. nicotianae can accumulate higher amounts of terbium and ytterbium than that of the other heavy REEs from the same solution. A. nicotianae can also accumulated higher amounts of Sm than other REEs from a solution containing six light REEs.     

Total reflection X-ray fluorescence determination of rare earth elements in mineral water

A method is proposed for determination of lanthanum, cerium, praseodymium, neodymium, and samarium in mineral water by means of total-reflection X-ray fluorescence analysis. In this work, the combined technique of preconcentration of rare earth ions is used. This technique consists of coprecipitation of metal hydroxides on the collector (iron (III) hydroxide) and dispersive liquid–liquid microextraction of their complexes with 1-(2-pyridylazo)-2-naphthol by chloroform in the presence of ethanol. The use of the developed hybrid approach allows simultaneous determination of the mentioned metals in mineral water in the range n(10^–2–10¹) μg/L. The results of analysis of Arkhyz and Rychal-Su mineral waters by the proposed extraction–X-ray fluorescent method are confirmed by the literature data, obtained by inductively coupled plasma mass spectrometry.     

Determination of rare earth elements and thorium in britholite ore by energy dispersive X-ray fluorescence spectrometry

A radioisotope-excited X-ray fluorescence technique is applied for the determination of thorium and rare earth elements in britholite ore from Canada. An annular source of⁵⁷Co is employed for excitation of characteristic K X-rays of thorium and rare earth elements. The peak ratios of lanthanides were used to remove the difficulties because of overlapping lines at the 33–50 keV energy region. Matrix effects are examined also in detail and compensated for infinitely thick powdered ore sample. Results obtained in the analysis agree well with recommended values of Canada.     

Separation of rare earth elements by high-speed counter-current chromatography

Besides being widely used in electronic and glass industries, rare earth elements have recently been found to have important biological effects including the ability to stabilize and enhance interferon activity [J.J. Sedmak and S.E. Grossberg, J. Gen. Virol, 52 (1981) 195]. In this paper, the rare earth elements have been separated using a high-speed counter-current chromatography (HSCCC) centrifuge equipped with three multilayer coils connected in series. Two-phase solvent systems were composed of n-heptane containing di-(2-ethylhexyl)phosphoric acid (stationary phase) and dilute hydrochloric acid (mobile phase) where the partition coefficient of each can be optimized by selecting the proper hydrochloric acid concentration. The mobile phase was eluted through the column at a flow-rate of 5 ml/min, while the apparatus was rotated at 900 rpm. Continuous detection of the rare earth elements was effected by means of a post-column reaction with arsenazo III and the elution curve was obtained by on-line monitoring at 650 nm. Excellent isocratic separations of closely related rare earth elements were achieved at high partition efficiencies up to several thousand theoretical plates. Versatility of the present method was demonstrated in an exponential gradient elution of hydrochloric acid concentration where fourteen rare earth elements were all resolved in about 4.5 h.     

Determination of rare earth elements and heavy metals in river water by preconcentration on chelex 100 and neutron activation

The neutron activation determination of rare earth elements and heavy metals in river water has been studied with Chelex 100 resin as a preconcentration agent. The resin is applied directly as a support for irradiation and for radiochemical separation. The radioactive rare earth elements are recovered selectively and quantitatively from the irradiated resin by elution with hot 1 M sodium carbonate solution; radioactive heavy metals are recovered with 2 M nitric acid. Activities from each eluate are counted with a Ge(Li) detector connected to a multichannel analyzer; La, Sm, Eu, Dy, Mn, Cu and Zn can be determined. The recoveries were almost quantitative and the measurement of chemical yield was unnecessary.     

Proton induced X-ray emission (PIXE) analysis on thick samples exemplified on the rare earth elements

Summary A semiempirical procedure is developed for the calculation of the signal intensity for thick sample PIXE experiments. The calculated X-ray intensity emerged out of a thick sample is factorized into the overall produced intensity within a thick sample and an effective transmission factor for the X-ray self-absorption.The accuracy of this procedure is limited by the reliability of the experimental input parameters to about ±25%.We find as an important result of this study: The signal intensity is calculated as a function of the various experimental parameters, i.e. proton energy and sample composition including interelement- and matrix effects. This function is presented as a closed equation, which can be applied very easily, i.e. without large scale computers, to calculate the sample elemental concentration. The mass absorption coefficient of the sample most strongly influences the effective transmission term.Enhancement corrections are calculated for additional interfering rare earth elements j. No significant interelement-effects appear at concentrations c _j 2 weight%, where analysis by PIXE may be interesting. The calculated results agree well with experimental data for the rare earth elements in different matrices.Dedicated to Karl Gleu on the occasion of his 80th birthday     

Proton induced X-ray emission (PIXE) analysis on thick samples exemplified on the rare earth elements

Summary Proton Induced X-ray Emission (PIXE) analysis calibration curves (i.e. intensity of analytical signal as a function of concentration c _i ) are determined on thick solid samples with rare earth element concentrations c _i 0.3g/g. The calibration curves are linear at low concentrations c _i 0.3 weight% at proton energies 1.7E _PO 2.5MeV. The precision of the quantitative analysis amounts to ±4 %. The shape of the curves at higher concentrations may be understood by simple qualitative considerations.Distortions by interelement-effects caused by additional other rare earth elements j in concentrations c _j 2 weight% are not detectable. The agreement between the experimental and the calculated intensities for different matrices is very good at low concentrations c _i 1 weight% of analyte.

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Protoneninduzierte Röntgenspektralanalyse (PIXE) dicker Proben am Beispiel der Seltenen ErdelementeI. Experimentelle Bestimmung von Eichkurven, Genauigkeit und Matrixeffekten

Zusammenfassung Es werden Eichkurven (d. h. Intensität des Analysensignals in Abhängigkeit von der Analytkonzentration c _i ) für die protoneninduzierte Röntgenspektralanalyse (PIXE) dicker Festkörperproben mit Seltenen Erdelementen im Konzentrationsbereich c _i 0,3g/g aufgenommen. Diese Eichkurven verlaufen bei niedrigen Konzentrationen c _i 0,3 Gewichts-% und Protonenenergien 1,7E_PO2,5MeV linear. Die Genauigkeit der quantitativen Analyse beträgt ±4 %. Der Verlauf der Eichkurven bei höheren Konzentrationen kann durch einfache qualitative Überlegungen verstanden werden.Es werden keine Störungen durch Interelementeffekte beobachtet, die durch zusätzliche andere Seltene Erdelemente j in Konzentrationen c _j 2 Gewichts-% hervorgerufen werden. Die Übereinstimmung der experimentellen und berechneten Intensitäten für verschiedene Matrices ist bei niedrigen Analytkonzentrationen c _i 1 Gewichts-% sehr gut.

Dedicated to Karl Gleu at the occasion of his 80th birthday     

Studies on ion transport of some rare earth elements through solvating extractants immobilised on supported liquid membrane

The studies on ion transport of terbium and dysprosium through a porous supported liquid membrane (SLM) containing TOPO (trioctyl phosphine oxide) and TBP (tributyl phosphate) as immobilised carriers have been carried out. The effect of stirring of bulk solutions on permeability coefficient has been investigated. The permeability coefficient increases with increase in pH of source phase from 0–6, and hydrogen ion concentration from 0.01 to 0.1 M of receiving solution. The dependency of permeability coefficient on the carrier concentration has been explored. The effect of ammonium thiocyanate concentration on permeability coefficient has been studied. In order to develop a method for enrichment of rare earth elements, further investigations were carried out by using a hollow fibre membrane extractor. The mechanism of ion transport of terbium and dysprosium in SLM systems has been explained.     

Determination of rare earths in selected rare earth matrices by spark source mass spectrometry

Three methods of preparing rare earth samples for mass spectrographic analysis are presented. Techniques for adding appropriate internal standards are described and relative sensitivity factors for rare earth impurities in rare earths, lanthanum, yttrium and scandium matrices are presented. Although indium has some value as an internal standard in rare earth samples, best analytical results are obtained when selected rare earths are used as internal standards.     

ICP-MS同时测定植物性食品中稀土元素的方法研究

建立了植物性食品中16种稀土杂质(Sc、Y、La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb和Lu)元素的电感耦合等离子体质谱(ICP-MS)的分析方法.考察了基体效应及质谱干扰,应用In内标,有效地补偿基体效应所引起的测量偏差,建立修正公式校正质谱干扰.对照分析了参考标准物质.对所测定元素,校正曲线的相关系数为＞0.9990,方法的检出限低于2.2 pg/g(Sc为95pg/g),回收率为92%～106%,RSD优于3.2%(n=7).     

Detailed study on simultaneous separation of rare earth elements by capillary electrophoresis

Separation of all rare earth elements (REEs) by capillary zone electrophoresis was investigated in a system of alpha-hydroxyisobutyric acid (HIBA) as a main complex reagent and acetic acid (HAc) as an assistant complex reagent. In the combined system, ligand Ac- plays an important role in improving separation of Eu and Gd, and Y and Dy. The calculated ratio of Ac- to HIB- concentrations was compared and demonstrated that Eu and Gd, and Y and Dy tend to be separated at lower, and higher ratio of the two free ligands, respectively. An operational buffer system was developed for a complete separation of all REE ions.     

Determination of trace rare earth elements by X-ray fluorescence spectrometry after preconcentration on a new chelating resin loaded with thorin

A very stable chelating resin was prepared by adsorption of (o-[3,6-disulfo-2-hidroxy-1-naphthylazo]-benzenearsonic acid) (thorin) on a macroporous resin Amberlite XAD-7. The optimal conditions for preparing it were obtained through the study of the adsorption properties of the resin and the thermodynamic quantities of the adsorption processes. Likewise, the behavior of the loaded resin with the rare earth elements (REE) were studied (pH of retention, sorption kinetics, etc). The conditions to prepare a thin film with this system were also evaluated. The loaded resin was successfully used for the separation and preconcentration of Sm(III), Eu(III) and Gd(III) prior to their determination by X-ray fluorescence (XRF) spectrometry. The preconcentration factor obtained was 500 and the concentrations at low detection limit were 13.8, 17 and 15.7 microg l(-1) for Sm, Eu and Gd, respectively.