Simple method of determination of copper,mercury and lead in potable water with preliminary pre-concentration by total reflection X-ray fluorescence spectrometry

Total reflection X-ray fluorescence spectrometry and chemical pre-concentration procedures have been applied for the analysis of trace concentrations of copper, mercury, and lead in drinking water samples. A simple total reflection module has been used in X-ray measurements. The elements under investigation were pre-concentrated by complexation using a mixture of carbamates followed by solvent extraction with methyl isobutyl ketone. The preconcentration procedure was tested with the use of twice-distilled water samples and samples of mineral and tap water spiked with known additions of copper, mercury, and lead. The obtained recovery and precision values are presented. The minimum detection limits for the determination of these elements in mineral and tap water samples were found to be 40 ng l⁻¹, 60 ng l⁻¹, and 60 ng l⁻¹, respectively.     

Heavy ion induced K,L and M X-rays and their use in trace element analysis

Characteristic K, L and M X-ray and background production trends from high energy heavy ion bombardment were investigated on a series of target elements (14≤Z≤92) using 0.5 MeV/amu and 1 MeV/amu Nⁿ⁺, Oⁿ⁺, Cuⁿ⁺, Krⁿ⁺ and Xeⁿ⁺ beams. X-ray production for K and L shell X-rays roughly followed the same trends, i.e. increased yield with projectile size and energy and decreased yield with increasing X-ray energy. Broad simultaneous multielement coverage can be achieved using K, L and M Lines. Experimental detection limits of 0.8 to 10 ppm were obtained for elements between Mn and Se with K X-ray detection, between Sm and Pb using L X-ray detection, and for Th and U via M X-ray detection in biological samples with a 1MeV/amu Kr⁷⁺ beam of 70 nA for 1000 s. These detection limits are better for many elements than those obtained with a 1.65 MeV proton beam.     

Thickness determination for Cu and Ni nanolayers: Comparison of completely reference-free fundamental parameter-based X-ray fluorescence analysis and X-ray reflectometry

Monochromatized synchrotron radiation of the electron storage ring BESSY II has been used for the non-destructive thickness determination of nanolayered materials by two different methods. The aim of these investigations was the comparison of completely reference-free fundamental parameter-based X-ray fluorescence analysis with X-ray reflectometry to validate the quantification of X-ray fluorescence analysis as an absolute method. For this purpose, Cu and Ni layers with a thickness varying between 5 nm and 50 nm as well as double layers of both metals deposited on Si have been studied. In X-ray reflectometry characterization experiments, the tunability of the photon energy allows the determination of not only the total layer thickness but also the individual layer thicknesses of the Cu/Ni double-layer systems. Reference-free X-ray fluorescence analysis involves both the fundamental parameter approach and the knowledge of all relevant experimental parameters obtained by instrumentation calibrated absolutely.The layer thickness determined by both methods agreed within their combined uncertainties. In view of the limits of X-ray reflectometry for very thin layers, laterally inhomogeneous samples, and multi-elemental layer compositions, reference-free X-ray fluorescence analysis offers the potential for the thickness determination of such samples.     

Nuclear and atomic activation with heavy ion beams

Heavy ion activation has been studied as a method for determining hydrogen. The reactions used [e.g.¹H(⁷Li, n)⁷Be] are the “inverse” of well known reactions [e.g.⁷Li(p, n)⁷Be]. Nuclear activation parameters for the ion beams of interest (⁷Li²⁺,¹⁰B²⁺) have been studied. The analytical feasibility is demonstrated with the determination of hydrogen in titanium at the 100 and 30 ppm levels with relative precisions of 8 to 10%. Detection limits in titanium are in the 0.1 to 0.5 ppm range. Heavy ion bombardment is also accompanied by the emission of characteristic X-rays (“atomic” activation). The parameters governing X-ray emission and background production have been investigated. Experimental K and L X-ray yields from thick targets have been measured for many elements excited by Oⁿ⁺ beams of 0.5 to 7 MeV/amu and Kr⁷⁺ beams of 0.5 to 1 MeV/amu. The simultaneous determination of trace elements at levels of 10 to several 100 ppm in microsamples (∼10⁻⁵ g) is demonstrated on biological specimens. K and L X-ray yields and corresponding detection limits have also been measured with the⁷Li²⁺ and¹⁰B²⁺ beams used for the nuclear activation of hydrogen. With these beams (∼6 MeV/amu) simultaneous nuclear and atomic activation is possible, yielding an unusual multielement trace analysis capability covering hydrogen and medium and high Z elements.     

Measurement of trace element concentration in a metal matrix using total reflection X-ray fluorescence spectrometry

Total reflection X-ray fluorescence spectroscopy (TXRF) has been used in combination with synchrotron radiation in order to determine detection limits and lowest limits of concentration of trace elements in metal matrices. Two applications on irradiated material are described, where the TXRF method has some advantages, as compared to other detection methods, because only few micrograms of material is needed for the measurements. The first application is devoted to radiation damage studies on first wall material of future fusion reactors. Therefore, metal foils were irradiated with 590 MeV protons at PSI and the transmutational elements produced in the foils were measured. The second application is the assessment of radiation damage of core components in a nuclear power plant, e.g. the reactor pressure vessel. This is performed by the determination of the fast neutron fluence on the components using an activation reaction of ⁹³Nb which is a trace element in most reactor steels. Detection limits of a few picograms have been found in the experiments.     

Analytical possibilities of different X-ray fluorescence systems for determination of trace elements in aqueous samples pre-concentrated with carbon nanotubes

This study was aimed to achieve improved instrumental sensitivity and detection limits for multielement determination of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Se, Pb and Cd in liquid samples by using different X-ray fluorescence (XRF) configurations (a benchtop energy-dispersive X-ray fluorescence spectrometer, a benchtop polarised energy-dispersive X-ray fluorescence spectrometer and a wavelength-dispersive X-ray fluorescence spectrometer).The preconcentration of metals from liquid solutions consisted on a solid-phase extraction using carbon nanotubes (CNTs) as solid sorbents. After the extraction step, the aqueous sample was filtered and CNTs with the absorbed elements were collected onto a filter paper which was directly analyzed by XRF.The calculated detection limits in all cases were in the low ng mL^− 1 range. Nevertheless, results obtained indicate the benefits, in terms of sensitivity, of using polarized X-ray sources using different secondary targets in comparison to conventional XRF systems, above all if Cd determination is required.The developed methodologies, using the aforementioned equipments, have been applied for multielement determination in water samples from an industrial area of Poland.     

Comparative methods for determination of rare earths in geological and mineral samples

Particle induced X-ray emission (PIXE) has been used for the quantitative analysis of rare earth elements (REE) in thick targets prepared from geological and mineral samples. Measurements were made with 1 and 3 MeV proton beams. For comparison, determination of the same elements was made by X-ray fluorescence (XRF) using a²⁴¹Am annular source. Minimal detectable limits (MDL) have been estimated for the two situations. Neutron activation analysis (NAA) has also been used for the determination of REE at the ppm level.     

ICP-MS Determination of 23 Elements of Potential Health Concern in Liquids of e-Cigarettes. Method Development,Validation, and Application to 37 Real Samples

The lack of interest in the determination of toxic elements in liquids for electronic cigarettes (e-liquids) has so far been reflected in the scarce number of accurate and validated analytical methods devoted to this aim. Since the strong matrix effects observed for e-liquids constitute an exciting analytical challenge, the main goal of this study was to develop and validate an ICP-MS method aimed to quantify 23 elements in 37 e-liquids of different flavors. Great attention has been paid to the critical phases of sample pre-treatment, as well as to the optimization of the ICP-MS conditions for each element and of the quantification. All samples exhibited a very low amount of the elements under investigation. Indeed, the sum of their average concentration was of ca. 0.6 mg kg⁻¹. Toxic elements were always below a few tens of a μg per kg⁻¹ and, very often, their amount was below the relevant quantification limits. Tobacco and tonic flavors showed the highest and the lowest concentration of elements, respectively. The most abundant elements came frequently from propylene glycol and vegetal glycerin, as confirmed by PCA. A proper choice of these substances could further decrease the elemental concentration in e-liquids, which are probably barely involved as potential sources of toxic elements inhaled by vapers.     

X-ray fluorescence analysis in the nanogram region with a total reflected and a Bragg polarized primary beam

Improvements of the detection limit in photon induced X-ray fluorescence analysis are obtained by the reduction of the radiation background at constant excitation conditions. Two methods are presented: 1) Bragg-reflection at 2 ν=90° results in a beam linearly polarized and monchromatic. Positioning the detector at an angle 90° to the direction of the polarized beam suppresses the production of scattered photons from sample and sample carrier into the detector. The use of single crystals instead of amorphous scattering materials increases the intensity of the polarized beam, in some cases up to a factor 10⁴. Detection limits and actually used crystal materials and lattice planes for Braggreflection are given in tables. Samples may be of either form, liquid or solid, no special sample preparation is required. 2) The application of X-ray total reflection on the polished and plane surface of a reflector which serves as the sample carrier reduces the radiation background. In the case of X-ray total reflection there is scarcely a penetration of the X-rays into the reflector material. The penetration depth of some 100 Å in the reflector-substrate can be compared to an extreme thin foil of same thickness. Therefore the reflector-substrate combines its mechanical strenght, its compact and constant geometric form, its chemical resistance and the possibility of easy handling-with the low background properties of ultra-thin foils. Samples should be liquids where the liquid part of the matrix is evaporated and the remaining trace elements are investigated. Both method are capable of detecting elements in the nanogram region.     

EDXRF versus INAA in a pollution control of soil

Summary Elemental concentrations of soil samples collected in the vicinity of a Romanian fertilizer plant were determined by EDXRF and long half-life INAA. Lower limits of detection, obtained for various elements in soil by EDXRF technique with radioactive excitation sources (²³⁸Pu and ²⁴¹Am) and a HPGe detector are presented. Spurious effects characteristic for Ge detector X-ray spectrometry are evaluated and discussed, and methods to overcome this drawback are suggested. Special care was taken to subtract from the spectra the Ge Ka     

Determination of trace elements in water by radioisotope alpha-particle induced X-ray emission

An X-ray spectrometric system including²¹⁰Po -particle sources for excitation and a Si(Li) detector has been applied to determine the concentrations of trace elements in water samples. Thin targets were prepared by the evaporation of a known volume of water deposited on a Mylar backing. The system was calibrated using the internal standard method. Relative sensitivities were measured for 16 elements detected by their K, L and M X-rays. The results are compared with theoretical calculations. The minimum detection limits from 0.01 to 0.07 g/ml were obtained for 2000 s analysis time.     

Determination of trace amounts of rare earth and other elements in rice samples by ICP-AES with sample introduction by tungsten-coil electrothermal vaporization

Summary A device with tungsten-coil electrothermal vaporization for sample introduction into ICP has been proposed. It was applied to the determination of trace amounts of rare earth and other elements in rice samples. Several influencing factors were investigated in detail, such as drying and vaporization parameters, carrier gas flow rate, volume of vaporization chamber and matrix effects. Under optimal experimental conditions, the detection limits for Mg, Cu, Mn, Cr, Fe, Co, Ni and eight rare earth elements are of the order of 10⁻⁹−10⁻¹¹ g. The detection limits for the rare earth elements tested by the present method are comparable to and, in most instances, exceed those for the GFAAS and conventional pneumatic nebulisation-ICP-AES. A precision with RSD<6% was obtained.     

Developing electrodeposition techniques for preconcentration of ultra-traces of Ni, Cr and Pb prior to arc-atomic emission spectrometry determination

Electrodeposition is known to be proper for separation and preconcentration of extremely low concentrations of analytes from the bulk sample which is instrumentally very simple. In the present research, a combination of electrodeposition with arc atomic emission spectrometry (ED-AAES) method has been developed in order to improve the analytical performance of this spectrometry technique. The results show that sensitivity and detection limits by using ED-AAES were improved 1000–2000 folds over those of normal arc atomic emission spectrometry in determination of the selected elements. The detection limits for measurement of Ni, Cr and Pb were 2.56, 3.05 and 2.11 µg L^{− 1} for monodeposition and 3.31, 3.72 and 3.25 µg L^{− 1} for simultaneously deposition, respectively. The precision of determination was in the range of 2–4% RSD. Typical calibration graphs for these elements were linear up to 100 µg L^{− 1}, depending on the element and matrix.Application of this technique was also tested on determination of the studied elements in an electroplating plant's waste water. The accuracy of technique was verified by comparing the results of the waste water analysis with those of electrothermal atomic absorption spectroscopy as a reference standard method.The obtained results show that the combined technique (ED-AAES) has been progressed substantially toward the ultimate goal of direct interference-free determination of trace analysis in complex samples by AAES.     

Untersuchungen zur atomspektroskopischen Spurenanalyse in AIII BV-Halbleitermikroproben—VI Untersuchungen zur Schichtabtrennung,Profil- und Spurenanalyse an InSb-Materialien

A method for the determination of distribution profiles and traces in InSb-materials is described. Stripping of the layers of several nm thickness was achieved by anodic oxidation (galvanostatic conditions). The stripping method was optimized, and the thickness of the layers stripped was determined by ellipsometric measurements. Traces of elements were determined by atomic emission and flameless atomic-absorption spectrometry. Detection limits in the range of 10¹⁷ atoms/cm³ for a 1-cm² surface layer 60 nm thick were observed. Distribution profiles for Mg and Te in InSb are shown.     

Using the activation radiography in geological and geochemical studies

To study the spatial distribution of gold and other elements in various specimens, a method of neutron activation radiography has been elaborated based on irradiating the sample studied with neutrons followed by photoregistration of the induced activity of the element under examination. The main factors, such as the resolution, detection limit, as well as the optimal conditions of irradiation, exposure and photoexposure for obtaining the selective radiographs have been evaluated. Radiographic methods with a resolution of 1–100 m for studying the distribution of more than 30 elements having local detection limits of 10^–3–10^–8 g·mm^–2 have also been developed. Representative data on the regularities of element distribution in minerals and samples of ores and holding rocks were obtained by applying these methods to the analysis of geological and geochemical specimens.     

Characterization of solar grade silicon by Neutron Activation Analysis

An analytical method using neutron activation was developed in order to orientate and check different silicon elaboration processes either as solid ingots or ribbon shaped. This method without chemical separation after irradiation implies the use of a high efficiency semiconductor detector. A particular attention was paid to different causes of error and to the detection limits really obtained. These limits range from 10⁹ to 10¹⁵ at.cm^–3 for about 30 elements systematically locked for after a 72-h irradiation.     

Characterization of purified <Superscript>241</Superscript>Am for common impurities by instrumental neutron activation analysis

Americium is an important actinide element having versatile applications based on its alpha and gamma emissions. Multi-element determination of radioactive samples using ICP-AES technique may be affected by the presence of americium due to its rich emission spectra. With a view to characterize plutonium based fuels containing americium for trace metals by ICP-AES technique accurately, a high purity ²⁴¹Am (using a separation procedure developed in our laboratory) was prepared. To ascertain its chemical purity it is essential to determine its impurity contents accurately. Instrumental neutron activation analysis (INAA), being a sensitive multi-elemental technique, was employed to determine the concentrations of impurities in purified ²⁴¹Am. Detection limits for the common elements and rare earth elements have also been determined. Comparison is made with the analytical data obtained by the ICP-AES method.     

Determination of yttrium in xenotime ore by energy dispersive X-ray fluorescence spectrometry

A radioisotope-excited X-ray fluorescence analysis is applied for the determination of yttrium in xenotime ore. An annular¹⁰⁹Cd source is employed for excitation of characteristic K X-rays of yttrium. The dilution method using pure starch as a diluent has been examined. Critical thickness of diluted ore sample has been determined. For the estimation of yttrium concentration in xenotime ore, the scattered radiation technique has been utilized. The validity and precision of the method have also been investigated.     

Spectrochemical Determination of Metallic Pollutants At Sub Ppm Levels In Fresh Water Samples

Abstract

A quantitative method to analyse fresh water samples for ultratrace pollutants such as Cd, Cr, Fe, Mn, Ni, Pb, V and Zn has been developed. the impurities in the water sample were preconcentrated by the method of slow evaporation and collected on specpure graphite which was subsequently analysed by d.c. are excitation using NaF as the carrier. the mean relative standard deviation of the method employed is + 15%. the accuracy of the method reported has been found to be quite satisfactory as borne out by the results of the Intercomparison Run conducted by the International Atomic Energy Agency, Vienna for the determination of trace elements in water. the detection limits for the various elements are as follows: Ni, Pb, V : 1 ng/ml; Cd, Cr, Mn: 2 ng/ml; Fe: 15 ng/ml and Zn : 20 ng/ml. Some of these detection limits have been compared with those obtained in some of the recent techniques such as AAS, Laser Induced Fluorescence (LIF) and Laser Enhanced Ionization (LEI) or Opto-Galvanic Spectrometry(òGS). It has been found that there is a tenfold increase in sensitivity for Pb in the present method as compared to the above techniques except LEI while the detection limits obtained for other elements are comparable with those in other techniques.     

Possible use of low voltage accelerators in PIXE analysis

A low energy (200 keV) accelerator routinely used as a neutron generator has been modified and a procedure established to extend the use to include proton induced X-ray emission (PIXE) analytical method. With these modifications, the generator has been used to measure the proton induced X-ray emission cross sections for twenty-eight elements ranging from aluminium to lead at 160 keV bombarding energy. Using these cross sections, the minimum detection limits for trace element determination in a rock matrix of average atomic number 13 have been evaluated.