Determination Of Rare Earth Elements Research Articles

Determination of rare earth elements in synthetic calcium phosphates by high-resolution continuum source electrothermal atomic absorption spectrometry

Ceramic, cement and composite biomaterials have been developed based on hydroxyapatites (HA) and tricalcium phosphates (TCP), which are analogous in phase and chemical composition to the mineral component of bone tissue. The crystal structures of HA and TCP are arranged in isomorphic substitutions. Recently, research has focused on the modification of HA and TCP structures with ions of various metals, including rare earth ions (REEs), with the aim of creating materials with a range of beneficial properties for medical applications. REEs are known to have a number of useful properties, including antibacterial, antitumour, catalytic, magnetic and luminescent properties. The replacement of some of the Ca ions in the structures of HA and TCP with REE ions therefore makes it possible to obtain a material with biocompatibility and biological activity, giving it the required properties depending on the REE used and its concentration. In order to achieve the specified properties, it is necessary to control not only the structure (phase composition, lattice parameters of the powders) and the presence of characteristic functional groups, but also the chemical elemental composition. Modifications of hydroxyapatites and tricalcium phosphates containing from one to several different alloying elements are currently being developed. Various analytical methods are used for this purpose, including X-ray, atomic emission and a number of others. This article is devoted to the study of the analytical capabilities of the method of atomic absorption spectrometry with electrothermal atomization and a continuous spectrum source in relation to the determination of Eu and Yb in hydroxyapatites and tricalcium phosphates. The article considers the optimal conditions and modes of analysis, including temperature-time programs, the use of modifiers, the construction of calibration curves, and other factors that can be adjusted for more precise results. The results demonstrated the possibility of simultaneous determination of both Eu and Yb in the concentration range of 0.09 to 2 wt.%, with a relative standard deviation of less than 6 rel.%.

Determination of rare earth elements in ferrocarbonatite using ICP-AES and ICP-MS

AbstractA method has been developed for the determination of Rare Earth Elements (REEs) in ferrocarbonatite using Inductively Coupled Plasma—Atomic Emission Spectrometer (ICP-AES) and Inductively Coupled Plasma—Mass Spectrometer (ICP-MS). The conventional dissolution procedures are tedious, with large measurement uncertainty and are thus not suitable for certified reference material (CRM) production and exploration of REEs. The described method involves leaching of sample using 3 M HCl followed by dissolution of residue (silica and REEs) by HF then determined REEs using ICP-AES and ICP-MS. The leaching step prevents formation of fluoride precipitates of matrix (Ca, Mg, Ba and Al). The method has been validated using CRMs.

Determination of Rare Earth Elements, Zirconium, Hafnium, Thorium and Uranium in Ultramafic Rocks by ICP‐MS after RE‐UTEVA Resin Columns for Separation and Pre‐Concentration

A simple method was developed for the determination of REEs, Zr, Hf, Th and U in ultramafic rocks by inductively coupled plasma‐mass spectrometry with a combination of RE and UTEVA extraction resins for their separation and pre‐concentration. Ultramafic rocks were digested with HNO3‐HF‐HClO4 and finally turned into 11 mol l−1 HCl solutions together with H3BO3 to remove insoluble fluorides. The removal of matrix elements was achieved during the loading procedure. Following this, REEs on RE resin, and Zr, Hf, Th and U on UTEVA resin were eluted with 10 ml of 0.24 mol l−1 HCl, with recoveries better than 94.4%. This method was validated using reference materials JP‐1, DTS‐2B, OKUM, UB‐N, MUH‐1 and DZΣ‐2, and the measurement results for target analytes were comparable to literature values, indicating its applicability to the determination of REEs, Zr, Hf, Th and U at ultra‐trace level in ultramafic rocks.

Tetrafluoroboric Acid Digestion for Accurate Determination of Rare Earth Elements in Coal and Fly Ash by ICP-MS Analysis

Coal and coal-related fly ash often contain rare earth elements (REEs) that have the potential to be utilized as valuable mineral resources. Accurately determining the REE content in coal and fly ash is crucial for resource evaluation. The conventional approach involves using hydrofluoric acid (HF) to dissolve silicates and release REEs, which, however, prolongs the digestion process due to the additional step of complexing fluoride ions (F−) with boric acid (H3BO3). Determining the correct amount of H3BO3 for neutralization can be challenging, and in some instances, the binding of fluoride ions with certain lanthanides (Lns) hampers the accurate determination of all 14 naturally occurring rare earth elements in a single digestion batch by inductively coupled plasma mass spectrometry (ICP-MS). In this study, we present an alternative method that achieves the accurate determination of all 14 naturally occurring REEs using tetrafluoroboric acid (HBF4) followed by ICP-MS analysis. This approach eliminates the need for an F− complexing step. We tested this method on certified REE reference materials, including NIST 1632e (coal) and NIST 1633c (fly ash), as well as the REE geological reference material USGS AGV-1 (andesite). Our results demonstrated excellent recovery rates (relative standard deviation, RSD < ±10%), with a correlation coefficient (r2) exceeding 0.99. Using this method, we investigated the concentrations of all 14 REEs in coal and fly ash samples collected from various locations in the southwestern USA. This improved digestion technique streamlines the analysis process and enhances the accuracy of REE determination, facilitating a more comprehensive evaluation of REE-rich coal and fly ash deposits for resource exploration.

Correction to: Effective determination of trace rare earth elements in ThF4 by ICP-MS with different material pretreatment procedures

Correction to: Effective determination of trace rare earth elements in ThF4 by ICP-MS with different material pretreatment procedures

UV-Vis spectrophotometric determination of rare earth elements (REE) speciation at near-neutral to alkaline pH. Part I: m-cresol purple properties from 25-75 °C and Er hydrolysis.

The speciation and mobility of rare earth elements (REE) strongly depends on pH, which controls the formation of charged aqueous hydroxyl species. The latter potentially play an important role in controlling heavy REE adsorption on clay minerals in near-neutral to alkaline waters such as in regolith-hosted REE mineral deposits. However, accurate REE hydrolysis constants are needed for developing geochemical models that can predict the role of these charged species in natural systems. Here, we develop a robust experimental UV-Vis spectrophotometric method using m-cresol purple to determine in situ pH from 25 to 75 °C. This method is used to derive the average ligand number and hydrolysis constants of erbium (Er) at 25 °C in aqueous solutions with low ionic strength (≤0.001 mol L-1) at pH from ∼7 to 9.5 and in the presence of Er concentrations from 0 to 0.057 mM. The average ligand number ranges between 1 and 3 indicating that Er(OH)2+, Er(OH)2+ and Er(OH)03 control speciation in the experiments. The logarithm of the Er hydrolysis constants (, n = 1 to 3) derived at infinite dilution for the reaction Er3+ + nH2O = Er(OH)n3-n + nH+ are: , , . Implementation of these experimental data into a geochemical model indicates that the Er(OH)2+ and Er(OH)03 species are both stable in a much wider pH range than previously predicted. Consequently, the positively charged REE hydroxyl complexes can potentially control the fractionation of light vs. heavy REE via adsorption as observed in the formation of certain regolith-hosted REE deposits.

Validation of microwave acid digestion, diffusive gradients in thin-film preconcentration and inductively coupled plasma optical emission spectrometry methodology for the determination of REEs in natural zeolites.

The determination of rare earth element (REE) content in different natural minerals is of high interest due to their extensive use in modern and sustainable technologies. The REEs occurring in natural zeolites are specific to each deposit. This study presents the validation and evaluation of the measurement uncertainty for the determination of REEs (Ce, Dy, Er, Eu, Gd, La, Lu, Nd, Pr, Sm, Y, and Yb) in natural zeolites using microwave-assisted acid digestion and inductively coupled plasma optical emission spectrometry (ICP-OES) after diffusive gradients in thin-film preconcentration. A mixture of HNO3 : HCl : HF of 3 : 9 : 2 (v/v/v) and microwave digestion provided suitable recoveries for the analysis of two certified reference materials, CRM BCS-CRM 375/1 and CRM OREAS 460. Good linearity over the calibration range of 0-2 μg mL-1, with correlation coefficients of 0.9995-1.0000, was obtained for each REE by ICP-OES. The limits of quantification (LOQS), calculated considering the instrumental LOQs and the sample preparation by microwave digestion, were in the range of 0.20-0.60 mg kg-1. A supplementary step of preconcentration/matrix separation based on the passive sampling by diffusive gradients in thin-films (DGT) technique improved the LOQs by about 20 times after three days of passive accumulation, allowing the measurement of the concentrations of all studied REEs in natural zeolite samples. The proposed methodology is a suitable approach for the measurement of REEs at low concentrations in natural zeolite samples by ICP-OES, and it can be extended to other geological samples. The measurement uncertainty was calculated based on the validation data. The proposed method provides reliable results for the measurement of REEs in natural zeolites and was used to measure the specific concentrations of REEs in natural zeolite samples from three Romanian quarries. The REE concentration can be used as a fingerprint for each deposit.

Determination of rare earth elements in liquid-phase samples by superhydrophobic array-assisted spark-discharge LIBS

Determination of rare earth elements in liquid-phase samples by superhydrophobic array-assisted spark-discharge LIBS

Development of a simple and efficient two-step microwave-assisted digestion method for the determination of REEs, HFSEs and other elements in granite samples by ICP-OES

An efficient two-step microwave-assisted digestion for the determination of REEs, HFSEs and other elements in granite samples by ICP-OES.

Investigation on pretreatment method for the determination of rare earth elements in polymetallic mineral samples in Pan-Xi region by ICP-MS.

The polymetallic mineral samples in Pan-Xi region are rich in rare earth resources, and exploring an efficient and accurate analysis method is of great significance for their comprehensive utilization. In this study, the samples were decomposed by three methods, namely closed acid dissolution, open acid dissolution with five acid and alkali fusion with sodium peroxide, and the 15 REE were determined by inductively coupled plasma mass spectrometry (ICP-MS) with Rh and Re as internal standard correction elements. The comparative experiments were conducted using standard substances, and the results showed: (1) The detection limit of closed acid dissolution method was low with relative standard deviation (RSD) ranging from 2.51% to 9.56% and the accuracy of method (ΔlgC) ranging from 0.006 to 0.073, while the sample processing was long, and the results of some REE were low. (2) The RSD of open acid dissolution with five acid method ranged from 1.93% to 7.96%, and ΔlgC ranged from 0.004 to 0.045 with low results of the determination results of REE. (3) The alkali fusion with sodium peroxide method eliminated the influence of matrix effects by selecting instrument optimization, sample dilution, appropriate internal standard elements, etc. The RSD ranged from 1.24% to 6.49%, and ΔlgC ranged from 0.001 to 0.032. In conclusion, alkali fusion with sodium peroxide method has a fast analysis process, complete sample dissolution, and the accuracy and precision of test results can meet the requirements of specification (DZ/T0011-2015), which is most suitable for the analysis of REE in polymetallic mineral samples from Pan-Xi region.

Determination of ultra-trace rare earth elements in olivine by laser ablation-sector field-inductively coupled plasma-mass spectrometry

Ultra-trace rare earth elements (REEs) in olivine could be precisely measured by LA-SF-ICP-MS.

Accurate determination of ultra-trace rare earth elements by LA-ICP-MS/MS and its application to cassiterite for effective elimination of Gd and Tb false positive anomalies

This study reports a new method for in situ determination of ultra-low REE contents in cassiterite by LA-ICP-MS/MS with an O2 and mass-shift detection strategy to avoid Gd and Tb anomalies.

Voltammetry in Determination of Trace Amounts of Lanthanides—A Review

This paper presents an overview of approaches proposed in the scientific literature for the voltammetric determination of rare earth elements (mainly cerium and europium individually, as well as various lanthanides simultaneously) in manifold kinds of samples. The work is divided into chapters describing the most important aspects affecting the sensitivity of the proposed methods: the technique adopted (AdSV, ASV, CSV), complexing agents used, the kind of working electrode (mercury-based, noble metal or carbon electrodes) and the most popular electrode modifiers (e.g., metal film, carbon nanotubes, molecularly imprinted polymers). Analytical parameters of the procedures presented in the paper are collected in tables. The subsequent chapters are devoted to a detailed discussion of potential inorganic and organic interfering factors. The possibilities of simultaneous determination of several lanthanides in one sample and the influence of other lanthanides on the determined rare earth element were also discussed. Finally, the applications of the voltammetric procedures to the determination of rare earth metals in real samples with miscellaneous matrix is described. All analytical results were tabulated in order to compare the analytical suitability of the proposed procedures.

Effective determination of trace rare earth elements in ThF4 by ICP-MS with different material pretreatment procedures

Effective determination of trace rare earth elements in ThF4 by ICP-MS with different material pretreatment procedures

Sensitive determination of rare earth elements in liquid samples by spatial confinement assisted surface enhanced laser-induced breakdown spectroscopy

The rapid determination of rare earth elements (REEs) in liquid samples holds significant importance for various applications such as the exploration and development of REEs resources, quality control of the extraction process, regeneration and recycling of REEs, and monitoring of nuclear industry wastewater. This study employed spatial confinement assisted surface-enhanced laser-induced breakdown spectroscopy (SC-SE-LIBS) for REEs determination in liquid samples. Investigations were conducted into the impact of different material substrates, sample pretreatment methods, and spatial confinement cavity diameters on detection performance. The results reveal that the graphite substrate yields superior spectral signal intensity compared to other materials (Zn, Al, and Ni). The groove-constrained liquid–solid conversion (GCLSC) pretreatment method significantly enhances spectral stability and detection accuracy. The most favorable signal enhancement is achieved using a cylindrical spatial confinement cavity (CSCC) with an 8 mm diameter. Employing the optimized experimental conditions, quantitative analysis of six REEs (La, Ce, Pr, Nd, Gd, Y) in liquid samples was performed using analytical lines at wavelengths of La Ⅱ 394.91 nm, Ce Ⅱ 401.24 nm, Gd Ⅱ 404.99 nm, Nd Ⅱ 406.11 nm, Pr Ⅱ 417.94 nm, and Y Ⅱ 488.37 nm. The obtained calibration curves exhibited R2 fit coefficients above 0.99, with corresponding limits of detection (LoDs) of 0.021 μg/mL, 0.104 μg/mL, 0.312 μg/mL, 0.241 μg/mL, 0.036 μg/mL, and 0.045 μg/mL, respectively.

Determination of heavy metals and rare earth elements in sediment and river water of the Citarum Watershed

Citarum River and its tributary rivers flows through Bandung Regency, with the watershed area about 6080 km2. These rivers play important role for local people in various field. Unfortunately, the anthropogenic activities in Citarum watershed have caused some environmental problems such as erosion, sedimentation, and water quality deterioration. Many various elements and heavy metals enter into the river from industrial waste, domestic waste, and some lithogenic materials where they will be distributed to aquatic ecosystem components such as sediment and aquatic biota. The aim of this research is to determine the distribution of heavy metals and rare earth elements in water and sediment river in Citarum River and its tributary river. The heavy metals and rare earth elements were measured using neutron activation analysis technique that can determine many elements simultaneously. The samples were collected from 10 sampling stations, from Situ Cisanti (upper segment) to Saguling Reservoir inlet, in March 2022. The result indicated that there were 13 elements detected in river water that consist of Na, K, Ca, Al, Mg, Ti, Co, Zn, Rb, Rb, Sb, Cs, La, V. In river sediment, 25 elements were detected that consist of 9 major elements (Na, K, Ca, Fe, Al, Mg, Ti, V, Mn), 10 minor elements (Co, Zn, Rb, Sb, Cs, Ba, Ta, Cs, Th, U, Hf) and 6 rare earth elements (La, Sc, Ce, Sm, Eu, Yb).

Round-Robin Interlaboratory Study on Rare-Earth Elements in U.S.-Based Geologic Materials

In a study funded by the U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL), the University of North Dakota (UND) Energy and Environmental Research Center (EERC) performed a first-of-its-kind round-robin interlaboratory study (RRIS) to determine lab-to-lab and method-to-method variability in analyzing the rare earth element (REE) content of domestic resources. Analyses of REEs on eleven different materials were accomplished by the laboratories using four different procedures: ASTM D6357 (Procedure A), ASTM D4503 (Procedure B), an alternate in-house procedure for digestion and REE analysis (Procedure C), and neutron activation analysis (NAA). The results of the RRIS suggest that NAA is the most accurate and reliable method for many of the REEs in these types of materials; however, the method is limited in that it is able to determining only ten of the sixteen REEs. Five of the seven labs reporting data for Procedure A and three of the five labs reporting for Procedure B showed excellent performance in terms of repeatability, reproducibility, agreement with NAA, and SRM recoveries based on AOAC International guidelines on method performance. This indicates that when strictly followed these methods are suitable for REE determination in most materials, although are subject to the overall capabilities and experience of individual laboratories.

Application of Poly(caffeic acid) for the Extraction of Critical Rare Earth Elements.

Poly(caffeic acid) was synthesized and utilized for the extraction and determination of rare earth elements (REEs), thorium, and uranium. Oxidative polymerization of caffeic acid, a low-cost plant-based material, in the presence of ethylenediamine produced a granular, air-stable, and cross-linked polymer. The polymer is highly oxygenated and together with the amino group from ethylenediamine efficiently coordinates and preconcentrates these critical elements from aqueous media. Extraction was dependent on solution pH, amount of sorbent, and extraction time, while the concentration and flow rate of the desorption solution governed the recovery efficiency. Removal and recovery efficiencies greater than 98 and 90%, respectively, and low levels of detection ranging from 0.1 to 2.9 ng/L were achieved. Determination of these strategic elements in the presence of potentially interfering ions as well as in complex matrices such as well water and produced water samples also was demonstrated. The capacity of poly(caffeic acid) was determined with lanthanum as a representative REE to be 161.7 mg/g, establishing the promise of poly(caffeic acid) for larger-scale extractions in addition to the ability to screen sources for the presence of REEs.

Use of carminic acid immobilized in agarose gel as a binding phase for DGT: A new approach for determinations of rare earth elements

Recently, rare-earth elements (REEs) have attracted great interest due to their importance in several fields, such as the high-technology and medicine industries. Due to the recent intensification of the use of REEs in the world and the resulting potential impact on the environment, new analytical approaches for their determination, fractionation and speciation are needed. Diffusive gradients in thin films are a passive technique already used for sampling labile REEs, providing in situ analyte concentration, fractionation and, consequently, remarkable information on REE geochemistry. However, data based on DGT measurements until now have been based exclusively on the use of a single binding phase (Chelex-100, immobilized in APA gel). The present work proposes a new method for the determination of rare earth elements using an inductively coupled plasma‒mass spectrometry technique and a diffusive gradients in thin films (DGT) technique for application in aquatic environments. New binding gels were tested for DGT using carminic acid as the binding agent. It was concluded that acid dispersion directly in agarose gel presented the best performance, offering a simpler, faster, and greener method for measuring labile REEs compared to the existing DGT binding phase. Deployment curves obtained by immersion tests in the laboratory show that 13 REEs had linearity in their retention by the developed binding agent (retention x time), confirming the main premise of the DGT technique obeying the first Fick's diffusion law. For the first time, the diffusion coefficients were obtained in agarose gels (diffusion medium) and carminic acid immobilized in agarose as the binding phase for La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu, which were 3.94 × 10−6, 3.87 × 10−6, 3.90 × 10−6, 3.79 × 10−6, 3.71 × 10−6, 4.13 × 10−6, 3.75 × 10−6, 3.94 × 10−6, 3.45 × 10−6, 3.97 × 10−6, 3.25 × 10−6, 4.06 × 10−6, and 3.50 × 10−6 cm2 s−1, respectively. Furthermore, the proposed DGT devices were tested in solutions with different pH values (3.5, 5.0, 6.5 and 8) and ionic strengths (I = 0.005 mol L−1, 0.01 mol L−1, 0.05 mol L−1 and 0.1 mol L−1 – NaNO3). The results of these studies showed an average variation in the analyte retention for all elements at a maximum of approximately 20% in the pH tests. This variation is considerably lower than those previously reported when using Chelex resin as a binding agent, particularly for lower pH values. For the ionic strength, the maximum average variation was approximately 20% for all elements (except for I = 0.005 mol L−1). These results indicate the possibility of a wide range of the proposed approach to be used for in situ deployment without the use of correction based on apparent diffusion coefficients (as required for using the conventional approach). In laboratory deployments using acid mine drainage water samples (treated and untreated), it was shown that the proposed approach presents excellent accuracy compared with data obtained from Chelex resin as a binding agent.

Determination of rare earth elements in uranium ores by ICP-MS after total dissolution with NH4F and matrix separation with TRU resin

Determination of rare earth elements in uranium ores by ICP-MS after total dissolution with NH4F and matrix separation with TRU resin