Group separation of trace rare-earth elements by countercurrent chromatography for their determination in high-purity calcium chloride

A method has been developed for the separation of the entire group of rare-earth elements from high-purity calcium chloride by countercurrent chromatography, and subsequent determination of the elements by ICP-MS. A solution of diphenyl[dibutylcarbamoylmethyl]phosphine oxide in chloroform (0.5 mol L(-1)) has been chosen as reagent for the extraction and preconcentration of trace rare-earth elements from aqueous 5% CaCl2 solution, 3 mol L(-1) in HNO3 and 0.1 mol L(-1) in HClO4. The analytes are back-extracted into a small volume of water and the aqueous eluate is subjected to ICP-MS measurements. The performance characteristics of the procedure developed have been checked by use of the standard addition technique and a real CaCl2 sample (Merck product) has been analyzed. The results obtained demonstrate the applicability of countercurrent chromatography to the determination of ultratrace elements.     

Use of organic additives for the detection of refractory elements in plasma atomic fluorescence spectrometry

A study of the effect of alkane gases on the atomic fluorescence signals of some refractory elements has been made, with a low power inductively coupled plasma (ICP) as the atomiser, and a high power ICP as the source. Detection limits are, for some elements, inferior to those obtainable by ICP-Atomic Emission Spectrometry (ICP-AES). However, an improvement by a factor of two has been obtained for tungsten by using ethanolic solutions instead of adding traces of hydrocarbon gases.     

Frequency-modulated simultaneous multielement atomic absorption spectrometry using electrothermal atomizer and deuterium background correction

Characteristic data of the frequency-modulated simultaneous multielement atomic absorption spectrometry (FREMSAAS) using electrothermal atomizer with deuterium background correction, have been determined. The data obtained have been processed by using several statistical tests recommended for quality control purposes. The instrumentation has been presented as well as procedures of separating elements into measure groups and fixing of variable conditions. Detection limits, characteristic masses and working ranges have been given for the eleven elements examined. The data have been in good agreement to results obtained with conventional one-channel AAS instruments. The eleven elements have been simultaneously determined in a standard reference material (SRM) and all results are compatible with a 95% certainty with the certified values. FREMSAAS has been applied to a real sample.Dedicated to Professor Dr. Dieter-Klockow on the occasion of his 60th birthday     

TXRF analysis of aged three way catalysts

A methodology for the quantitative analysis of the elements present in car exhaust catalysts by TXRF is described. Some of the most relevant catalytic components (Zr, Rh, Pd) and contaminant elements (P, Pb, Zn, Pt, Ca and Ni) on car Three Way Catalysts were quantified during vehicle aging. The study was conducted along the main axis of a Ford Focus 1.6i catalytic cartridge, aiming to obtain the axial profile of the elements retained or eliminated after more than 59,000 km. The analysis of a fresh Three Way Catalysts (0 km) was also conducted for comparative purposes. The existence of a strong differences for elemental concentration in the interphase between the two blocks of the catalytic cartridge has been quantitatively measured for first time. In addition, the behaviour of the contaminant absorption capacity of both catalytic blocks has been obtained. Finally, the loss of the contaminant elements Pb and Zn to the environment has been proven.     

Separation and determination of rare earth elements by Dowex 2-X8 resin using sodium trimetaphosphate as elution agent

The distribution coefficients of rare earth elements and thorium with Dowex 2-X8, 200-400 mesh, a strongly basic anion-exchange resin, have been determined regarding four different concentrations of sodium trimetaphosphate (3 x 10(-3), 5 x 10(-3), 7 x 10(-3) and 0.01 M). The separation of the rare earths and thorium obtained from an Australian monazite has been investigated by anion-exchange chromatography with sodium trimetaphosphate concentration gradient on a Dowex 2-X8 ion-exchange columns. The order of elution of the elements was the reverse of the order of elution of the same elements on Dowex 1 resin. The elution was investigated using 5 mg and 250 mg samples. In the separation of 5 mg samples, all elements were separated in 29 min. It has been seen that the elution peaks are narrow, tailing effects are very small, Dy and Y are well separated. Qualitative and quantitative determinations were realized by spectrofluorometry.     

Determination of protein-bound trace elements in bovine kidneys

Concentrations of up to 16 elements have been determined in subcellular fractions of bovine kidney using INAA methods. Levels of Rb and Se have been measured by a cyclic INAA method. A conventional INAA method consisting of 2 irradiations and 3 counting periods has been employed to determine the other elements. Accuracy of measurements has been evaluated by analyzing several standard reference materials. Trace element content of reagents used has been investigated in detail. Fresh samples of bovine kidney have been homogenized in a buffer containing sucrose and HEPES, and the homogeneate separated into nuclei, mitochondrial, lysosomal, microsomal and cytosol fractions by successive differential centrifugation. Concentrations of trace elements have been measured in these fractions using the INAA methods.     

Investigation on the preconcentration of trace elements on polyacrylonitrile

Summary Trace amounts of Co, Ni, and Mn have been enriched from aqueous solutions by retention of their ions on polyacrylonitrile (PAN). The recovery has been determined as a function of the amount of PAN, pH, the concentration of eluent (HCl) and the volume of sample solution. The elements were removed with 100% efficiency by means of conc. HCl. Recoveries were up to 95% depending on the elements. The resin has been used in combination with atomic absorption spectrophotometry for the determination.     

Diagnostic and analytical study of post ablation ionization of neutral atoms of major and minor constituents from a low alloy steel

Post ablation ionization (PAI) of neutral atoms from a low alloy steel has been investigated using non-resonant laser ionization in a time-of-flight mass spectrometer. By varying the delay between the ablation and ionization lasers, the velocity distributions of the Ti, V, Cr, Mn and Fe atoms have been determined simultaneously. These distributions have been recorded as a function of ablation laser fluence. The half-range Maxwell-Boltzmann velocity distribution has been used to fit the data and different characteristic temperatures have been determined for the various elements in the sample. The quantitative capability of this method for bulk and surface analysis has been evaluated by calculating the relative sensitivity factors (RSFs) for the various constituent elements. The RSFs for all of the elements are seen to be highly dependent on the delay between the ablating and ionizing lasers. This dependence was reduced by integrating the temporal dependent ion yield, leading to a significant improvement in the calculated RSF values. It was also found that the RSFs were not highly dependent on the power density of the ablation laser beam.     

Group separation of trace rare-earth elements by countercurrent chromatography for their determination in high-purity calcium chloride

A method has been developed for the separation of the entire group of rare-earth elements from high-purity calcium chloride by countercurrent chromatography, and subsequent determination of the elements by ICP– MS. A solution of diphenyl[dibutylcarbamoylmethyl]phosphine oxide in chloroform (0.5 mol L^–1) has been chosen as reagent for the extraction and preconcentration of trace rare-earth elements from aqueous 5% CaCl2 solution, 3 mol L^–1 in HNO3 and 0.1 mol L^–1 in HClO4. The analytes are back-extracted into a small volume of water and the aqueous eluate is subjected to ICP–MS measurements. The performance characteristics of the procedure developed have been checked by use of the standard addition technique and a real CaCl2 sample (Merck product) has been analyzed. The results obtained demonstrate the applicability of countercurrent chromatography to the determination of ultratrace elements. Received: 6 December 2000 / Revised: 27 February 2001 / Accepted: 6 March 2001     

Liquid-liquid extraction of elements by antipyrine and diantipyrylmethane salts from non-aqueous solutions or in systems without an organic solvent

The liquid-liquid extraction method for inorganic compounds has been developed and further improved by using different types of multiphase systems involving pyrazolone derivatives. The degree of concentration of elements by use of three-phase liquid systems has been increased by 1-2 orders of magnitude, and a universal method for preconcentration of elements in non-aqueous media has been suggested. The development of extraction systems based on a single liquid component-water-and not requiring an organic solvent at all, has increased the safety of extraction methods and improved the working conditions. A new variant of spectrochemical analysis without mineralization of an extract has been developed. Its main advantage is that it reduces the analysis time by a factor of 6 or 8. The liquid-liquid extraction of elements in purely aqueous two-phase systems without an organic solvent can be combined with titrimetric, photometric and polarographic determination in hybrid analytical procedures.     

Chemical separation and inductively coupled plasma–atomic emission spectrometric determination of seventeen trace metals in thorium oxide matrix using a novel extractant – Cyanex-923

Comprehensive studies have been carried out on the extraction behaviour of thorium matrix vis-a-vis 17 trace metallic elements using a novel extractant viz. Cyanex-923. The near total extraction of thorium and quantitative separation of these metals has been established using inductively coupled argon plasma–atomic emission spectrometry (ICP–AES). The recovery of few representative elements has been confirmed by radio-active tracer studies. The studies carried out here have enabled determination of μg/l amounts of all analyte elements with a precision of better than 1% RSD with prior chemical separation from as low as 1 g thorium sample in just five chemical extractions.     

Ion exchange micro columns for on-line preconcentration of heavy metals II. On-line break-through test for zinc, cadmium and lead

An on-line break-through test for zinc, cadmium and lead has been carried out by means of a flow-through cell and computerized potentiometric stripping analysis. This test has been applied to seventeen ion-exchange materials and enabled within a short time a predecision about the suitability of a resin for a special preconcentration problem. For the determination of the three trace elements in drinking water five ion exchangers are found to be appropriate without restriction and eight resins with some restrictions (not suitable for all three elements, weak matrix influences).     

Determination of heavy metals in suspended matter in the storage lake “Bitterfelder Muldestausee”

Dissolved and particulate trace elements have been determined in 400 samples of both the inflow and the outflow waters of the storage lake “Bitterfelder Muldestausse” in order to investigate the sedimentation of 22 elements transported by the highly polluted Mulde River, an affluent of the river Elbe. Inductively coupled plasma mass spectrometry (ICP-MS) has been used to analyse filtered water samples because of its multielemental capabilities, the excellent detection limits, the wide linear calibration range and the high speed of analysis. A special leaching procedure has been employed for the very low amounts of the suspended matter collected from each water sample. The dissolved material has been also analysed by ICP-MS. Testing of the procedure employed by the analysis of a standard reference material (SRM BCR 146) and use of the standard addition method has resulted in both a good precision (1–7%) and accuracy. Despite the wide variation in the composition of the suspended matter samples the concentrations of the heavy metals in sediment samples and in the suspended matter have been found to be comparable. A balance of sedimentation has been calculated based on the mean values of concentrations of all elements investigated in both the water and suspended matter samples of the inflow and outflow. Results from this first study show that the storage lake acts as a sedimentation trap for Zn, Cu, Pb, Ni, Cr, Cd, U and Co.     

Ion exchange micro columns for on-line preconcentration of heavy metals

An on-line break-through test for zinc, cadmium and lead has been carried out by means of a flow-through cell and computerized potentiometric stripping analysis. This test has been applied to seventeen ion-exchange materials and enabled within a short time a predecision about the suitability of a resin for a special preconcentration problem. For the determination of the three trace elements in drinking water five ion exchangers are found to be appropriate without restriction and eight resins with some restrictions (not suitable for all three elements, weak matrix influences).     

Preconcentration and instrumental neutron activation analysis of acid rain for trace elements

A combination of instrumental and preconcentration neutron activation analysis (NAA) methods has been developed for multielement determination in acid rain. Concentrations of 24 elements have been measured in the particulate matter of rainwater by the instrumental NAA method which involves 3 irradiation and 4 counting periods. Trace elements in the soluble fraction of rainwater have been preconcentrated using Chelex-100 resin. Various factors that could influence the retention of elements on to the resin have been examined, and reagent and other blanks investigated in detail. Concentrations of 15 elements have been measured by directly irradiating the resins. A graphite furnace atomic absorption spectrometry method has been used for determining Cd and Pb levels in the soluble fraction. Precision and accuracy of the methods have been evaluated, and limits of detection and determination calculated. The methods have been applied to rainwater samples collected from 36 locations across Canada. Enrichment factors, interelement and inter-ion concentration correlation coefficients are discussed     

Relative elemental sensitivity factors in non-resonant laser-SNMS

Using a reflectron time-of-flight mass spectrometer, the ionization process in non-resonant Laser postionization Secondary Neutral Mass Spectrometry (SNMS) has been investigated. In particular, the postionization efficiencies (PIE) achieved by multi photon and single photon absorption have been compared by ionizing ten elements sputtered from a NIST standard reference material by excimer laser radiation of 248 nm, 193 nm and 157 nm. Only in the case of single photon ionization (SPI) the measured laser intensity dependence of the PIE can be understood quantitatively in terms of corresponding theory. From the results, absolute values of the SPI cross sections have been evaluated for atoms of nine elements, which show a total variation over about two orders of magnitude. Furthermore, even in the regime of high laser intensity, where the ionization of all atoms is completely saturated, different elements have been detected with relative sensitivity factors which scatter over about one order of magnitude. This has been attributed to element dependent variations of the effective ionization volume which are caused by the different kinetic energy and angular distributions of different sputtered atoms.     

Determination of isotope ratios of metals (and metalloids) by means of inductively coupled plasma-mass spectrometry for provenancing purposes — A review

Since considerable time, isotopic analysis of different elements present in a sample, material or object (such as the ‘light’ elements H, C, N, O and S and ‘heavy’ elements, such as Sr and Pb), has been used in provenancing studies, as several factors — defined by “the environment” or origin of the sample — can lead to measurable differences in their isotopic composition. For the light elements, traditionally, (gas source) isotope ratio mass spectrometry (IR-MS) is used, while for a long period of time, thermal ionization mass spectrometry (TIMS) was considered as the only technique capable of detecting subtle variations in the isotopic composition of the ‘heavier’ elements. However, since the introduction of the first inductively coupled plasma mass spectrometers (ICP-MS), considerable attention has been devoted to the development of methodologies and strategies to perform isotopic analysis by means of ICP-MS. While the relatively modest isotope ratio precision offered by single-collector ICP-MS may already be fit-for-purpose under some circumstances, especially the introduction of multi-collector ICP-MS instruments, equipped with an array of Faraday detectors instead of a single electron multiplier, has lead to tremendous improvements in the field of isotopic analysis. As a result, MC-ICP-MS can be seen as a very strong competitor of TIMS nowadays, while it even provides information on the small isotopic variations shown by some elements, that are not or hardly accessible by means of TIMS (e.g., elements with a high ionization energy). Owing to these new instrumental developments, the application field of isotopic analysis by means of ICP-MS is continuously growing, also in the field of provenance determination. This paper is intended as a review of the developments in and the recent applications of isotopic analysis by means of ICP-MS in this specific research field.     

Electro-deposition as a sample preparation technique for total-reflection X-ray fluorescence analysis

A one-step sample preparation by electro-deposition for total-reflection X-ray fluorescence (TXRF) analysis has been developed using a common three-electrode arrangement with a rotating disc as the working electrode. Several elements such as Cr, Mn, Fe, Co, Ni, Cu, Zn, Ag, Cd, Pb, As and U have been determined simultaneously in saline matrix. A special electrode tip has been constructed as a holder for the TXRF sample carrier, which consists of polished glassy carbon. The influence of parameters such as time, pH value, and trace element concentration on the deposition yield has been examined for 14 elements. From repeatability studies, the uncertainty in deposition yields at the 95% confidence level has been found to be less than 20% for most of these elements. Typical detection limits range from 5 to 20 ng/l under the experimental conditions applied here. By an appropriate choice of the reference element and by calculation of yield factors, reliable quantification can be achieved directly by internal standardization. First results obtained for the standard reference material CRM 505 are presented.     

Structures of IV group elements and solid phases of water

The structures of solid phases of water and IV(b) group elements of the periodic table (carbon, silicon, germanium, and tin) are compared. Both water and mentioned elements are characterized by high polymorphism. All mentioned elements and ice have a modification with a diamond structure. For all substances considered, except tin, modifications with the structure of a hexagonal analogue of diamond (lonsdaleite) have been known. The modification with the β-Sn structure has not been known only for ice and carbon. One of the germanium modifications is isostructural to ice III. Tin has a modification with the α-Fe structure. The same structure is observed for ices VII, VIII, and X. Both water and IVb group elements can form clathrate compounds with cavities in the form of Allen’s polyhedra. In water clathrates these cavities contain noble gas atoms (Ar, Kr, Xe) and various molecules. Clathrates of IVb group elements contain metal atoms as well as noble gas atoms.     

岩石样品中43种元素的高分辨等离子质谱测定

以ＨＮＯ３和ＨＦ高压密封溶样,选择各元素浓度分布高低兼顾的国标ＷＢＧ０７１０３和ＷＢＧ０７１０５作参考标准,以高分辨ＩＣＰ－ＭＳ仪器测定岩石样品中４０余种元素,方法检出限在０．１～１８８ｎｇ／ｇ之间,各元素相对标准偏差（ＲＳＤ,ｎ＝６）多在５％以下,方法已用于批缇岩石样品分析。