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.     

Radiochemical neutron activation analysis of rare earth elements in peridotitic rocks

The understanding of the geochemistry of basalt petrogenesis and the nature of the upper mantle requires the examination of such rocks as peridotites which in many cases are thought to represent upper mantle material. The mineralogical composition of peridotitic rocks in such that they accommodate large proportions of such trace elements as the transition elements but very small amounts of the rare earths and hygromagmaphile elements. The last two groups are often able to provide a large amount of information leading to petrogenetic models. Owing to the extremely low concentrations of the REE in peridotitic rocks it is necessary to separate them from other elements which will interfere with their precise determination. We have used a radiochemical neutron activation analytical method which is adapted from various published methods. It involves a post-irradiation sample fusion, two separate ion-exchange chromatographic stages and finally a fluoride precipitation. The RNAA procedure is capable of providing very precise REE data for perioditic samples and we have used it for the analysis of such rocks from several geodynamic environments.     

Precise determination of rare earth elements in rocks by neutron activation analysis

A pre-irradiation group separation method has been developed for the neutron activation analysis of rare earth elements (REE) and Ba in silicate rocks. REE and Ba were quantitatively separated from other elements by cation exchange column method. The chemical yield of each separation was monitored with Pr added to the sample powder before decomposition. The accuracy and precision were tested by repeated analyses of JB-1 and one analysis of BCR-1. In addition, it was found that REE distribution in a granitic rock powder was inhomogeneous and therefore special care must be taken for the sampling of granitic rock powders.     

X-ray fluorescence spectrometric analysis of erbium oxide for rare earth impurities

An X-ray fluorescence spectrometric method has been developed for the analysis of high purity erbium oxide for the determination of yttrium, terbium, dysprosium, holmium, thulium, ytterbium and lutetium oxide impurities in the concentration range 0.005–0.1%. The sample is taken in oxalate form, mixed with a binder (boric acid) in the weight ratio 31 and made into a double layer pellet. The analysis is done on a Philips PW 1220 X-ray fluorescence spectrometer using a LiF (200) analyzing crystal. The precision at each concentration of the standards and theoretical minimum detection limit for each element has been calculated.     

X-ray fluorescence analysis of rocks

Summary Modern methods for the determination of various elements in geological materials by XRFA are reviewed. XRFA theory and metrological characteristics are discussed in detail.

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Röntgenfluorescenzanalyse von Gesteinen

     

X-ray fluorescence analysis of terbium oxide and oxalate for rare earth impurities

Summary A method for the determination of samarium, europium, gadolinium, dysprosium, holmium and yttrium oxides in terbium oxide is described. The sample is converted to terbium oxalate, mixed with boric acid binder in the ratio 21, pelleted at a pressure of 20 tons over a boric acid backing pellet and irradiated with X-rays from a tungsten tube operated by Philips PW 1140 generator. The secondary X-rays thus generated are analysed by a LiF(200) crystal in Philips PW 1220 X-ray fluorescence spectrometer. The minimum determination limit is 0.01% for all rare earth oxides determined except for yttrium oxide for which it is 0.005%.

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Zusammenfassung Eine Methode zur Bestimmung der Oxide von Samarium, Europium, Gadolinium, Dysprosium, Holmium und Yttrium in Terbiumoxid wurde beschrieben. Die Probe wird zu Terbiumoxalat umgesetzt, mit Borsäure im Verhältnis 2 1 gemischt, mit 20 Tonnen Druck auf eine Borsäuretablette aufgepreßt und mit Röntgenstrahlen aus einer Wolframröhre bestrahlt, die mit einem Philips-Generator PW 1140 gespeist wurde. Die dabei entstehenden Sekundärstrahlen wurden mit Hilfe eines LiF-Kristalls (200) in einem Philips PW 1220 Röntgenfluoreszenz-Spektrometer analysiert. Die untere Grenze der Bestimmbarkeit liegt bei 0,01% für alle bestimmten Seltenerden-Oxide mit Ausnahme von Yttriumoxid mit 0,005%.

     

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.     

Determination of rare earth elements in fern leaves using instrumental neutron activation analysis

The lanthanides (REE) in 142 fern leaves collected from several sampling sites in Japan have been determined by neutron activation analysis, and the correlations between any two REEs in the logarithmic scattering diagram were examined. The relationship was expressed by the general formula, Y=aX+b with a correlation coefficient R. A strong positive correlation was seen between any two REEs in the diagram with a regression coefficient and a correlation coefficient close to unity. However, between Eu or Tb and other REEs the relationship was split into two lines with the same correlation coefficient. From the intercept b, the relative abundance of the two elements was determined for each REE and compared with those in hickory and tobacco leaves. These findings indicated that the abundance pattern of fern leaves is quite different from those of hickory and tobacco leaves. Namely, the relative abundance of La and Ce was quite similar in the three plants, but the abundance of the other REEs (Nd, Sm, Gd, Dy and Lu) was considerably lower in ferns than in hickory and tobacco leaves. For Eu and Tb the higher values obtained in fern leaves coincided with those of the two plants.     

Determination of rare earth impurities in ytterbium oxide by X-ray fluorescence spectrometry

Summary Determination of Kare Earth Impurities in Ytterbium Oxide by X-ray Fluorescence Spectrometry An X-ray fluorescence spectrometric method for the determination of traces of Ho, Er, Tm, Lu and Y oxides in the concentration range of 0.005–1% in ytterbium oxide is developed. The precision at various concentrations of the standards is given. Intensity corrections for line overlaps have been determined.     

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.     

Neutron activation analysis of rare earth elements in alered volcanic rocks /palagonite/ from a seamount

By means of INAA, REEs in the dredged rocks from a seamount /KH73-4-2/ in the East Mariana Basin were determined. Based on the REE patterns, the rocks are classified into two groups despite of alteration: highly altered palagonite of oceanic-island tholeiitic nature, and relatively fresh basaltic-andesitic rocks of alkaline rock nature.     

Determination of rare earth elements in rocks and meteorites by the radioactivation method

Methods of digestion of samples by acidic dissolution and in fused sodium peroxide were modified in conformity with the chemical composition of basalts, periotites and stone meteorites as well as the method of REE pre-concentration by the lanthanum fluoride cycle. The enriching methods were used for the neutron-activation determination of the individual rare-earth elements in rocks and meteorites with a sensitivity up to 10⁻⁸%.     

K-line X-ray fluorescence analysis of high-Z elements

X-ray fluorescence analysis with high-energy photons (typically 40–100 keV) is described. Measurement of K-lines from high-Z elements has attractive advantages, which are not available by L-line analysis in normal X-ray region. Through the comparison of excitation methods, it has been found that quasi-monochromatic beams with sufficient intensity and moderate spectral distribution are most suitable for improving the detection limit. Performances of other excitation methods and recent experimental trends are also discussed.     

Group separation of rare earth elements by liquid-liquid extraction for the neutron activation analysis of silicate rocks

Rare earth elements are isolated as a group from neutron activated rock samples by a new radiochemical procedure based on extraction with thenoyltrifluoracetone/phenanthroline in CHCl₃. The procedure consists of three extraction steps, obviates the use of anactive carriers and gives practically quantitative chemical yields, thereby avoiding fractionation of the individual rare earths. Details of the dissolution, chemical separations and counting procedure are given togther with an analysis of BCR-1.     

钕-铁系稀土永磁合金的X射线荧光光谱分析

采用X射线荧光光谱测定Nd—Fe系稀土永磁合金中La,Ce,Pr,Nd,Fe,Co成份。该方法既能克服基体效应又能解决标准样品的制备问题,分析方法简便、快速、准确。对于体系较复杂的Nd—Fe系稀土永磁合金,采用本方法RSD小于2％,方法的加标回收率97％-105．8％之间。     

Neutron activation analysis of the rare earth elements in rocks from the earth's upper mantle and deep crust

Three techniques for analyzing rare earth elements (REE) in geological materials are described, i.e. instrumental neutron activation analysis (INAA), neutron activation analysis with pre-irradiation chemical REE separation (PCS-NAA) and radiochemical neutron activation analysis (RNAA). The knowledge of REE concentrations in eclogites, peridotites and minerals from the earth's lower crust and upper mantle is very useful in constraining their petrogenetic history.     

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...     

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.     

Application of intrinsic Ge detectors to the instrumental neutron activation analysis for rare earth elements in rocks and minerals

Improvements in the specifications of low-energy, intrinsic Ge detectors have enabled the routine determination of the concentrations in geological samples of eleven rare earth elements, including lanthanum, without using a Ge(Li) detector. The efficiency of an intrinsic Ge detector is compared with a high-efficiency Ge(Li) detector, and a quantitative assessment of the effect of X-ray and gamma-ray interferences is given. Rare earth element abundances in four U. S. G. S. standard rocks have been determined.