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Schematic diagram of a typical HPLC or HPIC set-up with a simple isocratic mobile phase system. A chromatographic system basically consists of five modules: mobile-phase supply system; sample injection system; separation system; detection system; and interface and data processing system.
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High-performance liquid chromatography (HPLC) and ion chromatography (HPIC) have been widely used as cheap, relatively rapid, precise and accurate separation and quantification analytical techniques for the rare earth elements (REE). In this “Back to Basics” review, a general description of the basic components of instrumentation and the most commo...
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... HPLC or HPIC system basically consists of five main parts: (1) a mobile-phase supply system; (2) a sample injection system; (3) a separation system; (4) a detection system; and (5) an interface and data pro- cessing system. Such a basic set-up is schematically shown in Figure 1, where only one eluent (or mobile phase) is introduced into the system using a single high-pressure mechanical pump. The eluent flows through the system at a given flow rate. ...
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... analyte undergoes the separation process according to one of the HPLC or HPIC mecha- nisms (see e.g., Yost et al. 1980, Weston and). The separated components are then detected and quantified in the detection and data processing system (Figure 1). ...
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... a mobile-phase supply system, the key compo- nent is a high-pressure mechanical pump used for the delivery of a precise, reproducible, constant and pulse- free flow of the mobile phase (see isocratic set-up in Figure 1). With two or more pumps used for supply of two or more mobile phases, the delivery system is ope- rated either in a simple or a more complex gradient elution mode (see gradient elution set-up of two mobile phases in Figure 2). ...
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... most common type of mobile phase supply systems are isocratic (Figure 1) and gradient ( Figure 2). In an isocratic elution system, analytes are eluted using a constant mobile phase composition. ...
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... system contains one (Figures 1-2) or more on-line detectors. Some features of a good detector are the capacity to monitor column effluents, stable baseline, wide linearity of response, low noise-level, high sensitivity, high reproducibility, insensitivity to changes in flow rate and temperature, and response to all kinds of compounds of interest. ...
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We have developed a rapid and precise analytical technique for the determinations of Y and rare earth elements (REE) from silicate rock samples by preparing XRF glass beads and using laser ablation (LA)- ICP-MS. Combined with XRF analysis, abundances of 39 major and trace elements (Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti; Ba, Ce, Co, Cr, Dy, Er, Eu, G...
Lanthanoids (also known as rare-earth elements – REE) are well-known tracers of water–rock interaction processes due to their behavior being coherent with their atomic radii, and the capability of Ce and Eu to reflect redox conditions. However, analysis of REE in natural waters is hampered by their relatively low concentration (sub-pg g À1), and th...
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... The separation of yttrium from the rare earth elements REEs is extremely difficult and considered a challenging problem owing to their similar charge and ionic radii, for example, Y elutes very close to Dy and Ho [3,6,7]. This co-elution phenomenon interferes with the precise determination of Y, Dy and Ho [8]. ...
... In the case of complex matrices, separation methods are recommended [23]. Recently, solid phase extraction (SPE) has been used for matrix removal and pre-concentration of REE in water [24][25][26]. ...
This paper proposes a new method of sample preparation for the determination of rare earth elements (REE) by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) in challenging environmental samples with high Ba concentrations. The method consists in adding 10% (v/v) sulfuric acid to the wet sample digest, obtained after acid decomposition in an open system, in order to precipitate and separate BaSO4. The removal of BaO interference in Eu isotopes was efficient for Ba concentrations in solution higher than 0.1 mg L⁻¹. The methodology was applied to asphalt pavement and the crushed stone used to produce it. Accuracy was assessed using two certified materials, NIST 688 Standard Reference Material of basalt rock and Geological Survey G2 granite, resulting in acceptable recoveries. Additionally, all samples were decomposed by fusion, and the concentrations of major elements and Eu were determined by inductively coupled plasma optical emission spectrometry (ICP OES). Eu results were in agreement with the proposed methodology, and limits of detection for REE varied from 0.003 mg L⁻¹ (Lu) to 0.010 mg L⁻¹ (Gd). The NASC normalized profiles of REE in the crushed stone showed a positive Eu anomaly, that was not observed in the asphalt sample. As well, the latter was enriched in heavy REE (Tb-Lu), suggesting a loss of carbonatite minerals, consequently to the weathering of the pavement.
... Kantipuly and Westland [33] collected existing works to elucidate the available methods for lanthanide determination in geological samples. Afterward, other revisions related to advances in REE separation and quantification were published [24,[34][35][36]. Verma and Santoyo [35] reviewed the existing chromatographic methods for REE separation by RP-HPLC. ...
... Afterward, other revisions related to advances in REE separation and quantification were published [24,[34][35][36]. Verma and Santoyo [35] reviewed the existing chromatographic methods for REE separation by RP-HPLC. In this paper, the authors reported the use of α-hydroxyisobutyric acid (HIBA) as the most common component of the mobile phases of REE separation. ...
A methodology was developed to assay 15 rare earth elements (REE) (La to Lu and Y) in a surface water sample from a mining area. The samples were collected in the mining area of Lavras do Sul, RS, Brazil. Reversed phase high-performance liquid chromatography employing α-hydroxyisobutyric acid (HIBA), sodium dodecyl sulfate as the ion interaction reagent, and acetonitrile as the organic modifier was used. Analytical detection was performed by spectrophotometry after post-column derivatization with 4-(2-pyridylazo)-resorcinol (PAR). Different chromatographic parameters such as ionic interaction reagent, HIBA concentration, pH, and PAR reagent concentration were studied to achieve the best conditions for the individual separation of REE. The method was validated in terms of the main analytical characteristics (linearity, limits of detection and quantification, precision, interferences, and accuracy). A method for sample cleanup was discussed. Under optimized conditions, it was possible to separate 15 REE (La to Lu and Y) in less than 15 min, with resolution of peaks Y and Dy. The cleanup procedure ensured the selectivity required to determine REE in natural water samples. The accuracy was assessed by regression analysis against measurements by ICP-MS. The calculated quantification limits ranged from 0.07 to 0.48 µg mL⁻¹, for the most sensitive (Dy) to least sensitive (La), respectively.
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... pm), Ho (r = 90.1 pm) and Dy (r = 91.2 pm) [6], and the same valency state, Y is usually found together with heavy lanthanides and its separation from all other REE belongs to most difficult tasks of inorganic separations [7]. Therefore every improvement in the methods of separation of REE and in particular separation of Y from the lanthanides should be of interest to specialists in REE separation technology, but also to analytical chemists and radiochemists. ...
Separation of Y from other rare earth elements (REE) is difficult because of similarity of its ionic radius to ionic radii of Tb, Dy and Ho. In the new RP-HPLC system with C18 column, tetra-n-butyl ammonium hydroxide (TBAOH) as an ion interaction reagent (IIR), nitrilotriacetic acid (NTA) as a complexing agent at pH=2.8-3.5, and post column derivatization with Arsenazo III, yttrium is eluted in the region of light REE, between Nd and Sm and is base line separated from Nd and Sm and even from promethium. Simple model employing literature data on complex formation of REE with NTA and based on anion exchange mechanism was developed to foresee the order of elution of individual REE. The model correctly predicted that lanthanides up to Tb will be eluted in the order of increasing Atomic Number (At.No.) but all heavier REE will show smaller retention factors than Tb. Concurrent UV/VIS detection at 658nm and the use of radioactive tracers together with γ-ray spectrometric measurements made possible to establish an unique elution order of elution of REE: La, Ce, Pr, Nd, Pm, Y, Sm, Er, Ho, Tm, Yb, Eu, Lu, Dy+Gd, Tb, Sc. The real place of Y however, in this elution series differs from that predicted by the model (Y between Sm and Eu). The method described in this work enables selective separation of Y from La, Ce, Pr, Nd, Pm, Sm and all heavier REE treated as a group.
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... The Rare Earth Elements (REEs) are Scandium and Yttrium and the members of the Lanthanide group in the periodic table. Many of these metals are used in batteries, lasers, capacitors, superconductors [1], which make the purification process demanding through high purity requirements in some of these applications. Current industrial separation methods include liquid-liquid extraction, selective oxidation/reduction, and ion exchange chromatography [2]- [5]. ...
... Current industrial separation methods include liquid-liquid extraction, selective oxidation/reduction, and ion exchange chromatography [2]- [5]. Extraction chromatography is commonly used for analytical purposes [1] [6]- [9]. ...
... The isotopic composition of the multi-isotopic REEs may hold important information about nucleosynthetic processes (McCulloch and Wasserburg, 1978a;McCulloch and Wasserburg, 1978b;Sharma, 2006, 2007;Carlson et al., 2007;Gannoun et al., 2011;Qin et al., 2011), neutron capture and cosmic-ray exposure effects on meteorites (Eugster et al., 1970a;Eugster et al., 1970b;Burnett et al., 1971;Lugmair and Marti, 1971;Russ et al., 1971;Bogard et al., 1995;Hidaka et al., 2000a;Hidaka et al., 2000b;Hidaka and Yoneda, 2007;Hidaka et al., 2009) and mass fractionation effects (Albalat et al., 2012). Several previous studies have reported moderate success in separating the individual REE by HPLC (Sisson et al., 1972;Yoshida and Haraguchi, 1984;Cassidy and Chauvel, 1989;Meisel et al., 2001;Sivaraman et al., 2002;Haley and Klinkhammer, 2003;Verma and Santoyo, 2007), but these analytical developments have not yet transitioned into isotope geochemistry due to the lack of suitable HPLC systems that meet the stringent standards of this field. ...
... Thus, the REEs are of particular interest to geochemists and cosmochemists, but are also challenging to separate from each other at the level required for isotope geochemistry work. Several well-established methods have been employed for the bulk separation of REEs for geochemical applications by traditional column chemistry (e.g., Gast et al., 1970;Strelow and Jackson, 1974;Hooker et al., 1975;Walsh et al., 1981;Crock et al., 1984;Henderson and Pankhurst, 1984;Balaram, 1996;Baker et al., 2002;Pourmand et al., 2012) or by HPLC (see review by Verma and Santoyo, 2007). These methods are effective for obtaining bulk concentration data and chondrite-normalized REE patterns, which are often used to provide insight into a sample's history. ...
a r t i c l e i n f o Keywords: Chromatography HPLC HDEHP Rare-earth elements Ni isotopes Isotope geochemistry Traditional column chromatography techniques are restricted by several factors, including limitations on column length, resin grain size, elution time, and a general inability to slowly ramp up or down reagent concentrations along a gradient. Likewise, most existing high-performance liquid chromatography (HPLC) systems are not amenable to certain column chromatography techniques that require highly concentrated acids. Here, we outline the development of a Teflon HPLC (T-HPLC) system for application to a wide variety of chroma-tography problems. The primary factors that set the T-HPLC system apart from any currently available chroma-tography procedure are the following: 1) a fluid flow path enclosed entirely by Teflon, 2) fully automated elution schemes controlled by computer software, which allows for fresh mixing of reagents for each elution step, and fine scale gradient/ramp elutions, 3) temperature control of the entire system (up to 80 °C) for enhanced chemical separations and, 4) a modular design making the system easily adaptable to a variety of separation schemes. The effectiveness of the T-HPLC system is tested on two column techniques that are of particular interest to the geochemistry/cosmochemistry communities. The first application involves the separation of Ni from Mg, which is required for high precision Ni isotopic studies and for investigating the abundance of the extinct 60 Fe radionuclide. The T-HPLC system greatly simplifies and improves upon the classical technique. In a single pass on an 80 cm long column, we achieve excellent separation of Ni from Mg, with a much improved time frame (10 h versus 70 h). The second application is the separation of the individual rare earth elements from each other. The isotopic compositions of the multi-isotopic REEs (La, Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb and Lu) may hold important information about nucleosynthetic processes, cosmic-ray exposure effects in meteorites and airless bodies, and mass fractionation effects. For this application, we also developed a computer simulation that uses experimentally determined partition coefficients to simulate an elution curve in order to optimize the actual column elution scheme. Overall, we were able to achieve excellent separation of the multi-isotopic REEs from each other. Although the two applications that we explore are in the fields of geochemistry/cosmochemistry, the modular design and adaptability make the T-HPLC system useful to a wide array of scientific fields and industries.
... Because reference materials such as G-2 are used in calibration of instruments, for example, X-ray fluorescence spectrometry (Guevara et al. 2005), and in quality control for other analytical methods such as liquid chromatography (e.g. Verma and Santoyo 2007), any differences in mean values will be important for such purposes. The differences in confidence limits will also be important for calibrations based on weighted least-squares linear regression models and for quantitative assessment of data quality (e.g. ...
Basically, two main types of statistical methods – robust and outlier-based – are available for handling experimental data; we document here the application of the outlier-based method. Due to the unavailability of a suitable software system for statistically correct application of the outlier-based method, a new computer program, DODESSYS (Discordant Outlier DEtection and Separation SYStem), was written for the application of 33 discordancy test variants to experimental data, constituting contaminated or uncontaminated normal statistical samples. We illustrate the application of the discordant outlier-based scheme by five specific examples; three include univariate data for which this procedure was specifically designed and two are for bivariate data for which this methodology can be easily adopted. We thus report new statistical information on two reference materials (granite G-2 and sediment IAEA-417), bryozoan species from eastern Oman, a new improved Na/K geothermometric equation, and a more significant correlation with water depth of the abundance of meiofauna from the Gulf of Mexico. Recently, two sets of multi-dimensional discrimination diagrams for basic as well as acid rocks have been proposed from statistically correct methodology of natural logarithm-transformation of element ratios; the diagrams also require that these ratios should be normally distributed. We present numerous examples of application of these new diagrams for inferring tectonic setting of Archaean to Recent rocks, both before and after testing the datasets for discordant outliers. We recommend that outlying observations should always be evaluated for their discordancy.
... Efficiencies in terms of plate number can vary from a few hundred to several hundred thousand. A plate number of at least N > 2000 is a desirable value (Weston andBrown 1997, Verma andSantoyo 2007). In this study, the number of plates was 4450, 12134, 11037, 12473, 12188, 7799 and 10079 for F -, Cl -, NO 2 -, Br -, NO 3 -, PO 4 3-and SO 4 2-respectively, which was sufficient for all calibration points (Table 1). ...
A single-column suppressed ion chromatography technique was employed for the simultaneous determination of major and trace anions in sulfaterich groundwater samples. An analytical column, a self regenerating suppressor and sodium carbonate as the eluent were used to separate the anions. Method detection limits for the anions of interest were 10.4, 15.9, 36.8, 62, 60, 61 and 67 μg l⁻¹ for F⁻, Cl⁻, NO2⁻, Br⁻, NO3⁻, PO4³⁻ and SO4²⁻ respectively. The precision of the method was tested at five different concentration levels for each anion reference sample to evaluate the effectiveness of the method for groundwater analysis. Recovery studies were performed between two successive months by adding reference samples to the geothermal groundwater and drinking water samples. Precision was also assessed as the relative standard deviation of both repeatability (within-day) and reproducibility (between-day and different concentrations) for groundwater samples. Standard deviation and RSD values of 220 groundwater samples acquired over 8 months were evaluated. The suppressed ion chromatography technique was found to be a suitable method for determining major anions in sulfate-rich geothermal water samples.
... Apart from this, the present evaluation of GSJ sedimentary RMs also allows to propose recommended values for the fi rst time for: (1) n: number of measurements; x: mean value; s: standard deviation; CL: 95% confi dence limit; lit: literature data (Imai et al., 1996); tw: this work (results obtained from the updated database of the present work); Ot%=outliers percentage.Table 1. Statistical parameters for chemical data from the literature (Imai et al., 1996) and this work for the geochemical sedimentary reference material JCh-1 (chert).sion models as well as for evaluation of method precision, accuracy, sensitivity and detection limits (Baumann, 1997; Zorn et al., 1997; Santoyo and Verma, 2003; Guevara et al., 2005; Santoyo et al., 2006; Tellinghuisen, 2007; Verma and Santoyo, 2007). Consequently, better quality data could be obtained in future for geological materials, which would facilitate proposal and use of new discrimination diagrams widely used in geosciences (e.g., Verma, 2009b, in press). ...
Nine geochemical sedimentary reference materials (RMs), JCh-1, JDo-1, JLs-1, JSl-1, JSl-2, JLk-1, JSd-1, JSd-2 and JSd-3, of the Geological Survey of Japan (GSJ) were evaluated by an objective outlier rejection statistical method. An extensive chemical database for these reference materials, created from the Internet website of the GSJ Geochemical Reference Samples Database (http://riodb02.ibase.aist. go.jp/geostand/) and from research articles published up to December 2008, is evaluated by a statistical scheme consisting of: (i) detection and elimination of the discordant outlier values with the application of 33 discordancy test variants (instead of routinely used inaccurate "two-standard deviation" method); (ii) calculation of new central tendency and dispersion parameters; and (iii) comparison of confi dence limits (calculated by incorporating the recently available new, precise critical values for Student t-test) and normalized mean difference percentages of the geochemical parameters obtained in the present work with those calculated for the data of the literature. Evaluation of these RMs by application of the more appropriate statistical method resulted in more precise new central tendency and dispersion parameter values, and also facilitated to propose recommended values for the fi rst time for some of the geochemical parameters. The results obtained in this work could be useful for better calibrations models and for evaluation of method precision, accuracy, sensitivity and detection limits.
