Ultra-trace Rare Earth Elements Research Articles

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 rare earth elements in small volumes of porewater from marine sediments by laser ablation solution sampling ICP-MS

An accurate method for ultratrace rare earth elements quantification in highly saline water with small volume sample consumption by laser ablation solution sampling ICP-MS.

Effect of ultra-trace rare earth elements on continuous cooling transformation curve of low carbon steel * *Fund projects: Inner Mongolia Autonomous Region Natural Science Foundation (2018ms05052); Liaoning Provincial Natural Science Foundation (2019-kf-25-08); Inner Mongolia University of Technology (zd201510); Inner Mongolia University of technology science and technology innovation fund for college students. Ruifeng Dong (1972 -), female, from TUZUO banner, Inner

Two groups of low carbon steel with ultra-micro amount (less than 20 ppm) rare earth lanthanum and without rare earth element were taken as experimental objects. Continuous cooling transformation curves of two kinds of low carbon steels were drawn by Formaster-F II automatic phase transformation instrument, alloy phase method and hardness method. According to the measured CCT curve, the microstructure and hardness of low carbon steel under different cooling rates were studied and analysed. The results show that the addition of ultra-trace rare earth elements can increase the Ac1 and Ac3 points of low carbon steel by about 20 °C; the starting temperature of martensite transformation MS point decreased by 19 °C, and the end temperature Mf point decreased by 6 °C; at low cooling rate, the transformation range of ferrite is increased and that of pearlite is decreased; the starting temperature of bainite Bs point increased by 20 °C, and the end temperature of bainite Bf increased by 13 °C; at low cooling rate, the ferrite transformation range becomes larger, while at high cooling rate, the ferrite transformation range becomes smaller.

The determination of ultra-trace rare-earth elements in iron minerals via HR-ICP-MS following chemical purification by polyurethane foam

This paper employed polyurethane foam to separate an iron matrix for the determination of ultra-low rare earth elements in iron minerals.

Determination of ultra-trace rare earth elements in high-salt groundwater using aerosol dilution inductively coupled plasma-mass spectrometry (ICP-MS) after iron hydroxide co-precipitation

Analysis data of rare earth elements (REEs) in high-salt groundwater can potentially provide a series of geochemical indicators. Accurate determination of sub-ng L−1 levels of REEs by inductively coupled plasma-mass spectrometry (ICP-MS) is still a challenge because of low concentrations, significant matrix effects from the highly dissolved salts, and mass spectral interferences. A reliable method, based on online aerosol dilution ICP-MS after co-precipitation with Fe(OH)3, was evaluated for the determination of REEs in high-salt groundwater. First, an Fe(OH)3 co-precipitation procedure effectively separated the target REEs from the high-content matrix elements (i.e. K, Na, Ca, and Mg); over 93% of the matrix elements were removed and target REEs were concentrated 15-fold. Secondly, using the proposed online aerosol dilution technique resulted in diminished residual matrix effects and the reduction of mass spectral interferences from oxide ions (i.e. Ba and light REE-oxides) by up to 10-fold. The detection limits of the method ranged from 0.05ngL−1 for Lu to 0.6ngL−1 for Nd, with the REE recoveries between 90% and 125%. The results for a seawater standard reference material (NASS-6) agreed with literature reported values. The proposed method was employed for the analysis of five high-salt groundwater samples. The accurate results showed that this method has great potential for the determination of ultra-trace levels of REEs in various high-salt water samples.

Determination of ultra-trace rare earth elements in ultramafic and sulfide samples by quadrupole inductively coupled plasma-mass spectrometry

A method has been developed for the determination of rare earth elements (REE) in ultramafic and sulfide samples by quadrupole inductively coupled plasma-mass spectrometry (ICP-MS). After Na2O2 fusion, REE analytes are separated and preconcentrated by inorganic coprecipitation combined with triethanolamine. By addition of REE standards to unknown samples, the procedural recovery was evaluated, and the mean value is 96.7%. Detection limits for this method are 4.46 ng g−1 for Ce to 0.02 ng g−1 for Ho. This method was validated using ultramafic standard samples, and the results are comparable to the accepted values.

Sequential determination of ultra-trace highly siderophile elements and rare earth elements by radiochemical neutron activation analysis: Application to pallasite meteorites

An analytical scheme of radiochemical neutron activation for the sequential determination of ultra-trace rare earth elements (REEs) and highly siderophile elements (HSEs) in geological and cosmochemical samples is presented. Using this procedure, several selected elements of REEs and HSEs were successively determined for geological reference samples and olivine crystals separated from pallasite meteorites. Based on the data for geological reference samples, it was concluded that the procedure presented in this study could yield data usable for cosmochemical discussion of the genesis of pallasite meteorites.

Separation of rare earth elements from scandium by extraction chromatography: Application to radiochemical neutron activation analysis for trace rare earth elements in geological samples

An effective and practical radiochemical separation procedure of radiochemical neutron activation analysis (RNAA) for ultra trace rare earth elements (REEs) in silicate rock samples is presented. The procedure consists of two column separations of anion exchange and extraction chromatography and precipitations as hydroxide and fluoride of REEs. The most seriously interfering nuclide, 46 Sc , is completely separated (<0.005%) from REEs by extraction chromatography using transuranic-element specific (TRU.Spec) resin. Chemical yields were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and found to be constant within 3% for all REEs, implying that no fractionation occurs among REEs during the radiochemical purification procedure. By means of this procedure, other interfering nuclides than 46 Sc in RNAA of silicate samples were decreased down to <0.02% for 59 Fe , <0.006% for 60 Co and <0.000005% for 51 Cr . The RNAA procedure described in this paper can be one of the most suitable analytical procedures for accurately determining ultra-trace (1–10 pg) REEs in geological and cosmochemical samples.

Determination of rare-earth elements in sulfide minerals by inductively coupled plasma mass spectrometry with ion-exchange preconcentration

A procedure was developed for determining ultratrace rare-earth elements in sulfide minerals by inductively coupled plasma mass spectrometry with ion-exchange preconcentration. The concentration factor was 200. The found concentrations of rare-earth elements were 6–30 times lower than those in chondrites. For lanthanum and praseodymium, RSD < 10%; for other rare-earth elements, RSD < 6%. The accuracy of the results was verified by the addition of known amounts of Eu, Tb, Tm, and Lu to a chalcopyrite sample at the stage of decomposition with HCl and HNO3. The calculated yield of rare-earth elements was 94–96%. The detection limit was from 0.06 ng/g (6 × 10–9%) for lutetium to 5 ng/g (5 × 10–7%) for cerium. The procedure was used for the determination of rare-earth elements in chalcopyrites, pyrites, and sphalerites.

Mini-Scale Solid-Phase Collection and Concentration of Ultra-Trace Elements in Natural Waters for the Simultaneous Multielement Determination by Air-Flow Injection/ ICP-Mass Spectrometry

Abstract A mini-scale solid-phase collection and concentration method for the multielement determination of ultra-trace rare earth elements (REEs) in natural water samples was developed by using a newly designed small-scale filtration apparatus. A small-size chelating resin disk (iminodiacetate type: IDA; 10 µm pore size; 5 mm diameter; 0.5 mm thickness) was used for high-enrichment preconcentration of REEs and for elimination of alkali and alkaline earth metals in sample solutions. At pH 5.5, REEs in artificial river waters were quantitatively collected on the chelating resin disk, and most of alkali and alkaline earth metals were removed. The REEs on the chelating resin disk were completely recovered by ultrasonication of the disk with 1 cm3 or less of 0.1 mol dm−3 nitric acid. A small amount (25 µL) of the concentrated sample solution was automatically injected and measured by inductively coupled plasma – mass spectrometry (ICP–MS) coupled with an air flow injection (AFI) system.

Micro-column separation/preconcentration combined with fluorinating electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry for determination of ultratrace rare earth elements

A new method for the determination of ultratrace amounts of lanthanum, europium, yttrium and ytterbium by micro-column separation/preconcentration combined with fluorinating electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (FETV-ICP-AES) has been developed. The 2-ethylhexyl-hydrogen-2-ethylhexyl phosphonate (P507) resin was used as the stationary phase. Various factors influencing the separation/preconcentration were studied in detail, and the influences of the organic matrix P507 and the pre-ashing temperature on the determination results were also investigated. Under optimized conditions, the detection limits for La, Eu, Y and Yb were 140, 33, 35 and 29 ng l−1, respectively, and the relative standard deviations ranged from 4.5% (La) to 2.5% (Yb). The proposed method was applied to the analysis of a biological reference material (Human Hair), and the results obtained were in good agreement with the reference values.

Preconcentration of ultratrace rare earth elements in seawater with 8-hydroxyquinoline immobilized polyacrylonitrile hollow fiber membrane for determination by inductively coupled plasma mass spectrometry

8-Hydroxyquinoline immobilized on polyacrylonitrile hollow fiber membrane was synthesized and used for the preconcentration of rare earth elements (REEs) and the separation of the matrix in seawater prior to their determination by inductively coupled plasma mass spectrometry (ICP-MS). Both the capacity and chemical stability of the modified polyacrylonitrile hollow fiber membrane have been evaluated. The optimum experimental conditions, such as pH, sample flow rate, volume of eluents, were investigated. The concentration of REEs in seawater and the separation of the matrix components can be achieved with a concentration factor of at least 300 times. The recommended method has been applied for the concentration and determination of REEs in coastal seawater. Results indicated that the recovery of REEs ranged from 91% to 107%, and the relative standard deviations were found to be less than 5%. A comparison was made between the REE levels determined by this method and the literature reports, and a reasonable agreement was obtained.

Determination of ultra-trace rare earth elements in chondritic meteorites by inductively coupled plasma mass spectrometry

A method for the direct determination of ultra-trace rare earth elements (REE) in seven Chinese chondritic meteorites by inductively coupled plasma mass spectrometry (ICP-MS) was developed. Samples were digested with a mixture of HF+HNO 3 acids in Teflon pressure bomb. The accuracy and precision of the method were assessed by the analysis of four standard reference materials including one chondrite (Allende) and three basalts (BCR-1, BHVO-1 and W-2), the results obtained in this study agree quite well with the recommended values. The reproducibilities (expressed as RSD) of samples were less than 5%.

Study of the preconcentration and determination of ultratrace rare earth elements in environmental samples with an ion exchange micro-column

A study was carried out on the preconcentration of ultratrace rare earth elements (REEs) in environmental samples with a micro ion-exchange column and determination by inductively coupled plasma mass spectrometry (ICP-MS). The preconcentration parameters were optimized and the REE recovery was ca. 100% in the pH range 4 to 6 with an ionic strength (μ) less than 0.18. The ion-exchange column capacity with respect to REEs was estimated as 0.96 mmol/g. The linear response coefficients ranged from 0.995 to 0.997 at the pg mL–1 level. The concentration in the blank could be minimized (0.09 to 3.1 pg mL–1) if the buffer solution and the water were purified. The detection limits ranged from 0.03 to 0.40 pg mL–1, for a preconcentration factor of 100. The precision and accuracy of the method was evaluated with a synthetic standard solution and real samples. Results indicated that the REE recovery ranged from 88.1% to 100.2%, and the RSD ranged from 2.7% to 6.7%. Satisfactory results were achieved when this method was applied for the determination of REEs in raw water, purified water and tap water, as well as in environmental aquatic samples. Meanwhile, the method is simple and flexible.

Determination of ultratrace rare earth elements in tea by inductively coupled plasma mass spectrometry with microwave digestion and AG50W-x8 cation exchange chromatography

The concentration of ultratrace rare earth elements (REEs) in tea was accurately determined by inductively coupled plasma mass spectrometry (ICP-MS), based on microwave digestion for sample preparation and AG50W-x8 cation-exchange chromatography for separation of REEs from the matrix. The spectroscopic interferences of matrix-induced polyatomic ions BaO+, BaOH+ with Eu+ were eliminated. The application potential of the method was evaluated by analysis of Certified Reference Materials of Tea (GSV-4) and Bush Twin Leaf (GSV-2). A good agreement between the results and certified values was observed. The recoveries of spiked samples for each REE were from 90 to 105% with a precision of <9% RSD. Very low levels of procedure blanks were maintained from 0.007 to 0.6 ng cm–3. The limits of detection (LOD) were between 0.0039 and 0.0003 ng cm–3 for REEs in solution. The results suggested that the developed method was very effective for the determination of REEs in tea. The levels of REEs in naturally grown teas were low but foreign REEs could accumulate in tea.