Determination Of Rare Earth Impurities Research Articles

Solid phase separation and ICP-OES/ICP-MS determination of rare earth impurities in nuclear grade uranium oxide

A simple, effective and low cost solid phase extraction procedure was standardized for the trace and ultra-trace level determination of rare earth impurities, such as, Ce, Dy, Sm, Gd, Eu, Er etc. which act as neutron poisons, in nuclear grade uranium oxide (U3O8 > 99.9% by weight). The method involves selective separation of these elements as their fluorides with the help of activated charcoal from major uranium matrix followed by determination by ICP-MS and high resolution ICP-OES. The residual uranium content of the solution was <10 μg/mL. The recovery of REEs ranges from 85 to 105%. The method was validated with nuclear grade uranium oxide standards CRM-I to CRM-V (BARC, Mumbai, India) in addition to some synthetic standards. The RSD of the method was ±12% (n = 3).

A Metal-coded Affinity Tag Approach to Quantitative Proteomics

The quantitative analysis of protein mixtures is pivotal for the understanding of variations in the proteome of living systems. Therefore, approaches have been recently devised that generally allow the relative quantitative analysis of peptides and proteins. Here we present proof of concept of the new metal-coded affinity tag (MeCAT) technique, which allowed the quantitative determination of peptides and proteins. A macrocyclic metal chelate complex (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)) loaded with different lanthanides (metal(III) ions) was the essential part of the tag. The combination of DOTA with an affinity anchor for purification and a reactive group for reaction with amino acids constituted a reagent that allowed quantification of peptides and proteins in an absolute fashion. For the quantitative determination, the tagged peptides and proteins were analyzed using flow injection inductively coupled plasma MS, a technique that allowed detection of metals with high precision and low detection limits. The metal chelate complexes were attached to the cysteine residues, and the course of the labeling reaction was followed using SDS-PAGE and MALDI-TOF MS, ESI MS, and inductively coupled plasma MS. To limit the width in isotopic signal spread and to increase the sensitivity for ESI analysis, we used the monoisotopic lanthanide macrocycle complexes. Peptides tagged with the reagent loaded with different metals coelute in liquid chromatography. In first applications with proteins, the calculated detection limit for bovine serum albumin for example was 110 amol, and we have used MeCAT to analyze proteins of the Sus scrofa eye lens as a model system. These data showed that MeCAT allowed quantification not only of peptides but also of proteins in an absolute fashion at low concentrations and in complex mixtures.

Determination of rare earth impurities in high purity samarium oxide using inductively coupled plasma mass spectrometry after extraction chromatographic separation

A method for the determination of trace of 14 rare earth elements (REEs) as impurities in high purity samarium oxide (Sm 2O 3) using inductively coupled plasma mass spectrometry (ICP-MS) was described. Analytes, such as La, Ce, Pr, Nd, Eu, Gd, Tb, Lu and Y were measured without Sm matrix separation because of no interference problems occurring that could affect the analysis of these elements. On the other hand, analytes, such as Dy, Ho, Er, Tm and Yb were carried out after Sm matrix being eliminated completely by means of 2-ethylhexyl hydrogen-ethylhexy phosphonate (EHEHP) extraction chromatographic separation. The inherent problem associated with matrix-induced suppression was effectively compensated with spiking In as internal standard element and the mass spectra isobaric interferences of atomic and molecular ions arose from Sm matrix had been overcome after the removal of Sm matrix. The limits of quantitations (LOQ) for 14 REEs impurities were from 0.01 to 0.07 μg g −1 together with the recoveries of spiking sample of 14 REEs were found to be in the range of 85–110% and the proposed method precision was less than 5%. A synthetic standard Sm 2O 3 sample with well-known 14 REEs concentrations was prepared and analysed in order to prove the accuracy and precision of the proposed method together with another high purity Sm 2O 3 was also measured using ICP-MS. The methodology had been found to be suitable for the determination of trace of 14 REEs in 99.999–99.9999% high purity Sm 2O 3.

Direct determination of rare earth impurities in high purity erbium oxide dissolved in nitric acid by inductively coupled plasma mass spectrometry

A novel method was developed for the direct determination of trace quantities of rare earth elements (REEs) in high purity erbium oxide dissolved in nitric acid by inductively coupled plasma mass spectrometry (ICP-MS) in this work. The mass spectra overlap interferences arose from Er matrix on the neighbouring and monoisotopic analytes of 165Ho(100) and 169Tm(100) were eliminated by adjusting instrumental peak resolution value from 0.7 to 0.3 amu. The matrix suppression effect of Er on the ion peak signals of REEs impurities was effectively compensated with spiking In as internal standard element. The limit of quantitation (LOQ) of REEs impurities was from 0.0090 to 0.025 μg g −1, the recoveries of spiked sample for REEs were found to be in the range of 90.3–107% through using the proposed method and relative standard deviation (R.S.D.) varied between 2.5% and 6.7%. The novel methodology had been found to be suitable for the direct determination of trace REEs impurities in 99.999–99.9999% high purity Er 2O 3 and the results obtained from this method keep in good agreement with that acquired from high resolution ICP-MS.

In-situ vaporization and matrix removal for the determination of rare earth impurities in zirconium dioxide by electrothermal vaporization inductively coupled plasma atomic emission spectrometry

A novel method for the determination of trace rare earth impurities in ZrO 2 powder has been developed based on electrothermal vaporization inductively coupled plasma atomic emission spectrometry. A polytetrafluoroethylene slurry was used as a fluorinating reagent to convert both the matrix (Zr) and the analytes (rare earth elements) into fluorides with different volatilities at a high temperature in a graphite furnace. The more volatile ZrF 4 was removed in-situ by selective vaporization prior to the determination of the analytes, removing matrix spectral interferences. Under optimum operating conditions, the absolute detection limits of the analytes varied from 0.04 ng (Yb) to 0.50 ng (Pr) with relative standard deviations less than 5%. The recommended approach has been successfully applied to the determination of trace rare earth impurities (La, Pr, Eu, Gd, Ho and Yb) in ZrO 2 powder and the results were in good agreement with those obtained by pneumatic nebulization inductively coupled plasma atomic emission spectrometry after the separation of the matrix using a solvent extraction procedure.

Determination of Rare Earth Impurities in High Purity Europium Oxide by Inductively Coupled Plasma-Mass Spectrometry and Evaluation of Concentration Values for Europium Oxide Standard Material

Direct determinations of 13 rare earth elements (La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Yb, Lu and Y) in high purity europium oxide by inductively coupled plasma mass spectrometry (ICP-MS) have been reported. The operating parameters of the instrument were optimized and the spectral interferences and the matrix effects were investigated. Using Ga or Rh as the internal standard can eliminate most of the matrix effects. The detection limits (3 sigma, n=10, integral time=1s) are 0.013-0.085 ng mL(-1) and the reproducibility (n=11) is 0.9-3%. The recoveries of spiking samples are 80-108%. Europium oxide standard material was made and its concentration values were evaluated by various techniques from 10 collaborating laboratories. By comparison of the results of ICP-MS with the results of other techniques, we have validated that ICP-MS is an accurate and reliable technique for analysis of ultratrace impurities in high purity rare earth matrix.

Determination of Rare Earth Impurities in High-purity Lanthanum Oxide Using Electrothermal Vaporization/ICP-AES after HPLC Separation

A new method for determination of trace rare earth impurities in high-purity La2O3 by HPLC combined with electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) is proposed. The chromatographic retention behaviors of matrix (La) and rare earth impurities were studied using 2-ethylhexyl hydrogen 2-ethylhexylphosphonate (P507) resin as the stationary phase and dilute nitric acid as the mobile phase. It was found that the use of EDTA as an eluent enables effective elution of rare earth impurities from a HPLC column. The influence of EDTA in ETV-ICP-AES was also discussed. The experimental results showed that a favorable separation between matrix (La) and rare earth impurities could be obtained within 30 min. The method proposed has been applied to the analysis of high-purity La2O3; the results obtained were in good agreement with those obtained by ICP-MS. Under the optimum conditions, the detection limits (DLs) for 14 rare earth elements (REEs) were in the range of 0.8 ng/ml (Yb) to 48 ng/ml (Ce). The recoveries of 14 REEs were in the range of 90% to 110%.

Determination of rare earth impurities in high purity gadolinium oxide by inductively coupled plasma mass spectrometry after 2-ethylhexylhydrogen-ethylhexy phosphonate extraction chromatographic separation

A method was developed for the determination of rare earth impurities in high purity Gd2O3 by inductively coupled plasma mass spectrometry (ICP-MS). The matrix suppression effect of Gd2O3 on signals of rare earth impurities was compensated for by Re internal standardization. The spectra overlap interferences from GdH, GdO, GdOHn (n=1–3) on Tb, Tm, Yb and Lu were eliminated by 2-thylhexylhydrogen-2-ethylhexy phosphonate (EHEHP) extraction chromatographic separation. The detection limits for REEs were 0.005–0.017 ng ml−1 in solution and 0.002–0.05 μg g−1 in solid. Recoveries of spiked sample for REEs were from 88 to 121% with the precision of 1.0–7.5% RSD. Determination of trace REEs in two Gd2O3 samples were performed. The method can be applied to analysis of 99.99–99.9999% high purity Gd2O3.

Direct determination of rare earth impurities in lanthanum oxide by fluorination assisted electrothermal vaporization inductively coupled plasma atomic emission spectrometry with slurry sampling

Slurry sample introduction with electrothermal vaporization (ETV) has been applied to inductively coupled plasma atomic emission spectrometry (ICP-AES) for the direct determination of rare earth impurities in lanthanum oxide. A polytetrafluoroethylene (PTFE) emulsion was used as fluorinating reagent to form volatile fluorides rather than refractory carbides of rare earth elements (REEs). The flow path of carrier gas between the graphite furnace device and the ICP torch was improved, and the main factors affecting the analytical signals, such as the flow rate of carrier gas and auxiliary carrier gas, matrix concentration, exposure time, vaporization temperature and vaporization time, were studied systematically. Under the optimum operating conditions, the detection limits (DL) for 14 REEs were obtained in the range of 2 ng ml–1 (Yb) to 130 ng ml–1 (Ce), and the relative standard deviation (RSD) is less than 5%. The recommended approach has been applied to directly analyse lanthanum oxide without any chemical pretreatment.

Determination of Rare Earth Impurities in High Purity Zirconium Dioxide by Electrothermal Vaporization Inductively Coupled Plasma Atomic Emission Spectrometry Using 1-Phenyl-3-Methyl-4-Benzoyl-5-Pyrazone as Extractant and Chemical Modifier

ABSTRACT A novel method has been developed for the determination of trace La, Eu and Y in high purity ZrO2 by electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) with 1-phenyl-3-methyl-4-benzoyl-5-pyrazone (PMBP) as extractant and chemical modifier. The matrix was quantitatively separated from the selected elements in 6M HNO3 medium by extraction with 0.1M PMBP in chloroform. The vaporization behaviors, effect factors and analytical characteristics of above selected elements were investigated in detail. Under the optimized conditions, the detection limits were 8.0, 0.9 and 1.0ng ml−1 for La, Eu and Y with the relative standard deviations of 3.3, 3.4 and 4.0% (n=7, c=0.5 μg ml−1), respectively. The proposed method has been applied to determine trace impurities in ZrO2.

Determination of rare earth impurities in ultrapure europium oxide by inductively-coupled plasma mass spectrometry

Trace quantities of rare earth elements (REEs) in ultrapure europium oxide (Eu 2O 3) are measured by inductively coupled plasma mass spectrometry (ICP-MS). The signal intensity of REE decreases with increasing concentration of europium oxide. Then, the internal standard method is examined to minimize this signal suppression. Four internal standards, cadmium ( 111Cd +) and indium ( 115In +), and thallium ( 205TI +) and bismuth ( 209Bi +) are investigated, since their mass numbers are close to those of lighter ( 89Y +- 157Gd +) and heavier ( 159Tb +- 175Lu +) REEs, respectively. The use of internal standards o Cd and In suppress interference for lighter REEs, and Tl and Bi for heavier REEs. These results imply the interference concerned with a mass-related space charge effect. In trace analysis of REE impurities in ultrapure Eu 2O 3, In and Tl are suggested to be used as internal standards for lighter and heavier REEs, respectively, due to the recoveries close to 100%. Lighter REE oxide ions occurring in a plasma generally interfere with the determination of heavier REEs. However, almost all REEs are determined correctly even at ultratrace levels by a proper selection of isotope. Unfortunately, polyatomic ions from the europium oxide such as 153EuO + and 153Eu 18OH + ions seriously interfere with the determination of 169Tm + and 172Yb +. These interferences are reduced by using ion chromatography (IC) combined with ICP-MS detection.

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

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 impurities in cerium dioxide and oxalate by X-ray fluorescence technique

A method for the determination of lathanum, praseodymium, neodymium and samarium oxides in cerium dioxide has been developed. The sample in the oxalate form is mixed with the binding material (boric acid) in the ratio 1∶1 pressed to form a double layer pellet over a boric acid backing pellet and irradiated by X-rays from a tungsten tube. The secondary X-rays are dispersed with a LiF (200) crystal in a Philips PW 1220 semiautomatic X-ray fluorescence spectrometer. The intensity of fluorescent X-rays is measured by a flow proportional counter. The minimum determination limit is 0.01% for lanthanum and samarium oxides and 0.02% for praseodymium and neodymium oxides. The precision at each concentration of the standards and theoretical minimum determination limit for each element have been calculated.

Determination of rare earth impurities in high purity uranium by isotope dilution analysis

An isotope dilution method for the determination of rare earth impurities in uranium has been developed and Ce, Nd, Sm, Eu and Gd have been determined in uranium oxide samples. The method involves isotopic dilution with enriched isotopes of the rare earths being measured, followed by the separation of rare earths from uranium. A mass spectrometer with thermionic source was used to determine the relative isotopic abundances in each of these rare earths. All these five elements were analysed selectively by preferential evaporation technique. Trace concentrations down to parts per billion range can be measured with good sensitivity and accuracy.

X-ray excited optical fluorescence of trace rare earths in yttrium phosphate and yttrium vanadate hosts. Part per giga level determination of rare earth impurities in yttrium oxide

X-ray excited optical fluorescence of trace rare earths in yttrium phosphate and yttrium vanadate hosts. Part per giga level determination of rare earth impurities in yttrium oxide

Concentration and determination of rare earth impurities in an yttrium matrix

Concentration and determination of rare earth impurities in an yttrium matrix

Quantitative spectrographic analysis of the rare earth elements—X: Determination of rare earth impurities commonly associated with purified thulium, ytterbium, lutetium and scandium

Emission-spectrometric methods are described for the following quantitative determinations: yttrium, holmium, erbium, ytterbium and lutetium in thulium; samarium, yttrium, erbium, thulium, lutetium and scandium in ytterbium; yttrium, thulium, ytterbium and lutetium in scandium. The basic method involves the d.c. carbon arc excitation of rare earth oxide-graphite mixtures. In all cases the percent deviation from the mean is less than ± 5 per cent.

Quantitative spectrographic analysis of the rare earth elements—IX: Determination of rare earth impurities commonly associated with purified samarium, gadolinium, terbium, and yttrium

Emission spectrometric methods are described for the following quantitative determinations: neodymium and gadolinium in samarium; neodymium, samarium, terbium, europium, yttrium, dysprosium and holmium in gadolinium; samarium, gadolinium, terbium, dysprosium, holmium, and erbium in yttrium; and samarium, gadolinium, yttrium and dysprosium in terbium. These methods cover the concentration range from the detection limit up to 1 per cent. The basic method involves the direct-current carbon arc excitation of rare earth oxide-graphite mixtures, utilizing the unique similarity in excitation behavior of many of the rare earths to provide a high degree of internal standardization. The coefficient of variation is less than ±5 per cent in all instances.