Total reflection X-ray fluorescence spectrometric determination of elements in water hyacinth from the Lerma River

The Lerma River is one of the most polluted body water in Mexico. For this reason, only the highly resistant organisms such as water hyacinth are able to reproduce in this river. The aim of this work was to evaluate the concentration of K, S, Fe, Ca, Mn, Ti, Zn, Sr, Rb, Cu, Cr, Ni, Pb and Br in roots of water hyacinth (Eichhornia crassipes) from the Lerma River. The samples were collected from five sites in the river and analyzed in triplicate using a TXRF Spectrometer ‘TX-2000 Ital Structures’ with a Si(Li) detector and a resolution of 140 eV (FWHM) at Mn Kα. A Mo tube (40 kV, 30 mA) with 17.4 KeV excitation energy was used for a counting time of 500 s. Results show that the average metal concentration in the water hyacinth roots decrease in the following order: K (9698.2 µg/g) > S (7593.3 µg/g) > Fe (4406.6 µg/g) > Ca (2601.8 µg/g) > Mn (604.2 µg/g) > Ti (230.7 µg/g) > Zn (51.65 µg/g) > Sr (43.55 µg/g) > Rb (18.61 µg/g) > Cu (12.78 µg/g) > Cr (6.45 µg/g) > Ni (4.68 µg/g) > Pb (4.32 µg/g) > Br (4.31 µg/g) and the bioconcentration factors in the water hyacinth decrease in the sequence: Ti > Fe > Mn > Cu > Ni > Zn > S > Pb > Rb > K > Cr > Sr > Br > Ca. The concentrations in roots of water hyacinth reflect the high pollution level of the river.     

X-ray fluorescence analysis of rare earth elements in rocks using low dilution glass beads.

Major and trace elements (Na, Mg, Al, Si, P, K, Ca, Ti, Mn, Fe, Rb, Sr, Y, Zr, La, Ce, Pr, Nd, Sm, Gd, Dy, Th and U) in igneous rocks were assayed with fused lithium borate glass beads using X-ray fluorescence spectrometry. Low dilution glass beads, which had a 1:1 sample-to-flux ratio, were prepared for determination of rare earth elements. Complete vitrification of 1:1 mixture required heating twice at 1200 degrees C with agitation. Extra pure reagents containing determinants were used for calibrating standards instead of the rock standard. The calibration curves of the 23 elements showed good linearity. Furthermore, the lower limits of detection corresponding to three times the standard deviation for blank measurements were 26 mass ppm for Na2O, 6.7 for MgO, 4.5 for Al2O3, 4.5 for SiO2, 18 for P2O5, 1.1 for K2O, 4.0 for CaO, 3.9 for TiO2, 1.6 for MnO, 0.8 for Fe2O3, 0.5 for Rb, 0.2 for Sr, 0.4 for Y, 0.5 for Zr, 3.3 for La, 6.5 for Ce, 2.7 for Pr, 2.1 for Nd, 1.7 for Sm, 0.7 for Gd, 2.7 for Dy, 0.5 for Th, and 0.6 for U. Using the present method, we determined the contents of these 23 elements in four rhyolitic and granitic rocks from Japan.     

Total reflection X-ray fluorescence study of organic nanostructures

X-ray scattering techniques based on total external fluorescence study and development of X-ray standing wave method are presented and used for characterization of organic nanostructure Langmuir–Blodgett films of fatty acid salts and phospholipids. Spectral selectivity of data obtained allows us to detect structure position of different ions in organic systems, to obtain information about interdiffusion at the interfaces, about ion permeation through organic bilayers, thus allowing us to develop models of biomembranes.     

Total reflection X-ray fluorescence analysis of Mongolian coals

Coal samples were analysed for trace elements using total reflection X-ray fluorescence with monochromatic excitation. The procedure involved direct irradiation of the sample with the incoherent peak as internal standard. A new method for spectrometer sensitivity determination and sample quantification, was evaluated. Variable amounts of several trace elements were obtained in the analysis of coal from eight different deposits of Mongolia. The accuracy of the procedure was verified with the analysis of a coal standard.     

Total reflection X-ray fluorescence analysis with chemical microchip

A chemical microchip, which has a flat region on the surface, was recently designed for total reflection X-ray fluorescence (TXRF) analysis. A sample solution was introduced from an inlet by a microsyringe and flowed into a microchannel. Finally it overflowed from the well-type microchannel on the flat region. The sample solution on this region was dried, and then measured by TXRF. The TXRF spectra could be measured with a low background level. This preliminary result indicated that the edge of the well-type channel would not cause a serious problem for TXRF analysis. In addition, a good linear relationship was obtained for Zn Kα in Zn standard solution. This suggests that quantitative analysis by TXRF is feasible in combination with a chemical microchip.     

Determination of rare earth elements and thorium in britholite ore by energy dispersive X-ray fluorescence spectrometry

A radioisotope-excited X-ray fluorescence technique is applied for the determination of thorium and rare earth elements in britholite ore from Canada. An annular source of⁵⁷Co is employed for excitation of characteristic K X-rays of thorium and rare earth elements. The peak ratios of lanthanides were used to remove the difficulties because of overlapping lines at the 33–50 keV energy region. Matrix effects are examined also in detail and compensated for infinitely thick powdered ore sample. Results obtained in the analysis agree well with recommended values of Canada.     

Analysis of mineral water from Brazil using total reflection X-ray fluorescence by synchrotron radiation

The total reflection X-ray fluorescence using synchrotron radiation (SRTXRF) has become a competitive technique for the determination of trace elements in samples that the concentrations are lower than 100 ng ml⁻¹. In this work, thirty-seven mineral waters commonly available in supermarkets of Rio de Janeiro, Brazil, were analyzed by SRTXRF. The measurements were performed at the X-Ray Fluorescence Beamline at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo, using a polychromatic beam with maximum energy of 20 keV for the excitation. Standard solutions with gallium as internal standard were prepared for calibration of the system. Mineral water samples of 10 μl were added to Perspex sample carrier, dried under infrared lamp and analyzed for 200 s measuring time. It was possible to determine the concentrations of the following elements: Si, S, K, Ca, Ti, Cr, Mn, Ni, Cu, Zn, Ge, Rb, Sr, Ba and Pb. The elemental concentration values were compared with the limits established by the Brazilian legislation.     

荧光光度法测定稀土元素研究进展

文章综述了近20年来国内外有关稀土元素荧光光度法的研究进展.主要从测定体系、测定波长、检出限、线性范围等方面对铈、铕、钐、镝、铽、镧、钇等稀土元素进行研究.最后对一些新的荧光技术如激光诱导时间分辨光谱、时间分辨荧光免疫分析等进行了简单讨论.文章引用文献69篇.     

Element determination in natural biofilms of mine drainage water by total reflection X-ray fluorescence spectrometry

Human impacts like mining activities lead to higher element concentration in surface waters. For different pollution levels, the consequences for aquatic organisms are not yet investigated in detail. Therefore, the aim of this investigation is to determine the influence of mining affected surface waters on biofilms.Elements like heavy metals can be absorbed on cell walls and on polymeric substances or enter the cytoplasm of the cells. Thus, they are important for the optimization of industrial biotechnological processes and the environmental biotechnology. Beyond this, biofilms can also play an important role in wastewater treatment processes and serve as bioindicators in the aquatic environment.The presented total reflection X-ray fluorescence spectroscopic investigation was performed to compare the element accumulation behavior of biofilms grown on natural or on artificial materials of drainage water affected by former copper mining activities. A high salt and heavy metal pollution is characteristic for the drainage water. For an assessment of these results, samples from stream Schlenze upstream the confluence with the drainage water, a small tributary of the Saale River in central Germany, were analyzed, too.     

Emission-spectrometric determination of trace rare earth elements in europium oxide

Summary A dc arc excitation method in a controlled atmosphere was applied in the presence of CsCl-graphite (19) buffer for the quantitative determination of traces of rare earth elements in europium oxide. The intensities of the cyanogen band spectra and the background could be reduced by the use of argon-oxygen (41) mixed gas atmosphere and it was possible to obtain higher sensitivity than in the excitation in air. Addition of CsCl-graphite buffer causes an increase of the evaporation rate of the sample and of the number of atoms in the arc plasma, and the atoms and ions of rare earths distribute uniformly along the axis of the discharge gap. The buffer enhances the sensitivity and reproducibility and permits the determination of microquantities of 10 impurity elements within limits of detection from 3 to 11 ppm in high-purity europium oxide. The coefficients of variation are less than 13%.

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Emissionsspektrometrische Bestimmung von Spuren Seltener Erden in Europiumoxid

Zusammenfassung Die Anregung erfolgt im Gleichstrombogen in kontrollierter AtmosphÄre (Argon/Sauerstoff, 41) in Gegenwart eines CsCl-Graphit (19)-Puffers. Durch die Verwendung von Argon/Sauerstoff konnte die IntensitÄt des Untergrundes und der Cyanbanden erheblich reduziert und eine grö\ere Empfindlichkeit erreicht werden als bei der Anregung in Luft. Durch den Puffer wird die Verdampfungsgeschwindigkeit erhöht, die Anzahl der Atome im Bogenplasma vergrö\ert und eine gleichmÄ\ige Verteilung der Atome und Ionen lÄngs der Bogenachse erzielt. Empfindlichkeit und Reproduzierbarkeit werden verbessert. Spurenverunreinigungen von 10 Elementen können in hochreinem Europiumoxid bestimmt werden. Die Nachweisgrenzen liegen zwischen 3 und 11 ppm; der Variationskoeffizient ist < 13%.

     

Determination of rare earth elements in mineral raw materials and rare earth industry products by neutron activation analysis

To determine REE in mineral raw materials, high purity RE metals and their compounds, neutron activation analysis with extraction chromatographic REE separation has been developed. Combination of the developed RE extraction and separation procedures with subsequent -spectrometric analysis of the RE radionuclides allows to determine their content with the lower detection limit –10^–5–10^–8%. The relative standard deviation is 0.2–0.3.     

Total reflection X-ray fluorescence trace mercury determination by trapping complexation: Application in advanced oxidation technologies

It is well known that Hg species cause high noxious effects on the health of living organisms even at very low levels (5 μg/L). Quantification of this element is an analytical challenge due to the peculiar physicochemical properties of all Hg species. The regulation of the maximal allowable Hg concentration led to search for sensitive methods for its determination. Total reflection X-ray fluorescence is a proved instrumental analytical tool for the determination of trace elements. In this work, the use of total reflection X-ray fluorescence for Hg quantification is investigated. However, experimental determination by total reflection X-ray fluorescence requires depositing a small volume of sample on the reflector and evaporation of the solvent until dryness to form a thin film. Because of volatilization of several Hg forms, a procedure to capture these volatile species in liquid samples by using complexing agents is proposed. Acetate, oxalic acid, ethylenediaminetetracetic acid and ammonium pyrrolidine–dithiocarbamate were assayed for trapping the analytes into the solution during the preparation of the sample and onto the reflector during total reflection X-ray fluorescence measurements. The proposed method was applied to evaluate Hg concentration during TiO₂-heterogeneous photocatalysis, one of the most known advanced oxidation technologies. Advanced oxidation technologies are processes for the treatment of effluents in waters and air that involve the generation of very active oxidative and reductive species. In heterogeneous photocatalysis, Hg is transformed to several species under ultraviolet illumination in the presence of titanium dioxide. Total reflection X-ray fluorescence was demonstrated to be applicable in following the extent of the heterogeneous photocatalysis reaction by determining non-transformed Hg in the remaining solution.     

A novel total reflection X-ray fluorescence procedure for the direct determination of trace elements in petrochemical products

A total reflection X-ray fluorescence (TXRF) procedure was developed for the determination of metal traces in petrochemical end products or intermediates for surfactant synthesis. The method combines a fast and straightforward sample preparation, i.e. deposition on the sample holder and evaporation of the sample matrix, with an efficient quantification method based on internal standardization (organic gallium standard). The method developed showed detection limits below 0.05 μg g^-1 and in most cases below 0.005 μg g^-1. Fifteen elements (Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Rh, Sn, Sr, V and Zn) were determined in matrices such as paraffins, n-olefins, linear alkylbenzenes, long-chain alkyl alcohols and esters: typical metal contents were below 1 μg g^-1. The results were compared with the reference method ASTM D5708 (test method B) based on inductively coupled plasma optical emission spectroscopy: advantages and drawbacks of the two procedures were critically evaluated. The TXRF method developed showed comparable precision and absence of bias with respect to the reference method. A comparison of the performances of the two methods is presented.     

Direct determination of trace elements in boron nitride powders by slurry sampling total reflection X-ray fluorescence spectrometry

The use of slurry sampling total reflection X-ray fluorescence spectrometry (SlS-TXRF) for the direct determination of Ca, Cr, Cu, Fe, Mn and Ti in four boron nitride powders has been described. Measurements of the zeta potential showed that slurries with good stabilities can be obtained by the addition of polyethylenimine (PEI) at a concentration of 0.1 wt.% and by adjusting the pH at 4. For the optimization of the concentration of boron nitride in the slurries the net line intensities and the signal to background ratios were determined for the trace elements Ca and Ti as well as for the internal standard element Ga in the case of concentrations of boron nitride ranging from 1 to 30 mg mL⁻¹. As a compromise with respect to high net line intensities and high signal to background ratios, concentrations of 5 mg mL⁻¹ of boron nitride were found suitable and were used for all further measurements. The limits of detection of SlS-TXRF for the boron nitride powders were found to range from 0.062 to 1.6 μg g^– 1 for Cu and Ca, respectively. Herewith, they are higher than those obtained in solid sampling and slurry sampling graphite furnace atomic absorption spectrometry (SoS-GFAAS, SlS-GFAAS) as well as those of solid sampling electrothermal evaporation inductively coupled plasma optical emission spectrometry (SoS-ETV-ICP-OES). For Ca and Fe as well as for Cu and Fe, however, they were found to be lower than for GFAAS and for ICP-OES subsequent to wet chemical digestion, respectively. The universal applicability of SlS-TXRF to the analysis of samples with a wide variety of matrices could be demonstrated by the analysis of certified reference materials such as SiC, Al₂O₃, powdered bovine liver and borate ore with a single calibration. The correlation coefficients of the plots for the values found for Ca, Fe and Ti by SlS-TXRF in the boron nitride powders as well as in the before mentioned samples versus the reference values for the respective samples over a concentration range from 2.5 to 1470 μg g^– 1 were found to be 0.995, 0.991 and 0.997, respectively.     

Uranium determination in seawater by total reflection X-ray fluorescence spectrometry

A study regarding uranium determination in seawater by total reflection X-ray fluorescence (TXRF) spectrometry is reported. Uranium, present in seawater in concentration of about 3.3 ng/mL, was selectively extracted in diethyl ether and determined by TXRF after its preconcentration by evaporation and subsequent dissolution in a small volume of 1.5% suprapure HNO₃. Yttrium was used as an internal standard. Before using diethyl ether for selective extraction of uranium from seawater, its extraction behavior for different elements was studied using a multielement standard solution having elemental concentrations in 5 ng/mL levels. It was observed that the extraction efficiency of diethyl ether for uranium was about 100% whereas for other elements it was negligible. The detection limit of TXRF method for uranium in seawater samples after pre-concentration step approaches to 67 pg/mL. The concentrations of uranium in seawater samples determined by TXRF are in good agreement with the values reported in the literature. The method shows a precision within 5% (1σ). The study reveals that TXRF can be used as a fast analytical technique for the determination of uranium in seawater.     

Total reflection X-ray fluorescence analysis of trace-elements in candies marketed in Mexico

Trace metals concentrations in food are significant for nutrition, due either to their nature or toxicity. Sweets, including chewing gum and candies, are not exactly a food, but they usually are unwearied consumed by children, the most vulnerable age-group to any kind of metal contamination in the food chain. The presence of relatively high concentrations of heavy metals such as Lead elicits concern since children are highly susceptible to heavy metals poisoning. Trace-metals concentrations were determined for six different flavors of a Mexican candy by means of Total X-ray Fluorescence Spectrometry. Triplicate samples of the various candy's flavours (strawberry, pineapple, lemon, blackberry, orange and chilli) were digested in 8 mL of a mix of supra-pure HNO₃ and H₂O₂ (6 mL: 2 mL) in a microwave oven MARS-X. Results show the presence of essential and toxic elements such as Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, and Pb. All metal concentrations were higher and significantly different (α = 0.05) in chilli candy, compared to other candy flavours. Lead concentration fluctuated in the range of 0.102 to 0.342 μg g^− 1. A discussion about risk consumption and concentration allowed by Mexican and International Norms is made. As a part of the Quality Control Program, a NIST standard of “Citrus Leaves” and a blank were treated in the same way.     

X-ray fluorescence spectrometric analysis of erbium oxide for rare earth impurities

An X-ray fluorescence spectrometric method has been developed for the analysis of high purity erbium oxide for the determination of yttrium, terbium, dysprosium, holmium, thulium, ytterbium and lutetium oxide impurities in the concentration range 0.005–0.1%. The sample is taken in oxalate form, mixed with a binder (boric acid) in the weight ratio 31 and made into a double layer pellet. The analysis is done on a Philips PW 1220 X-ray fluorescence spectrometer using a LiF (200) analyzing crystal. The precision at each concentration of the standards and theoretical minimum detection limit for each element has been calculated.     

Determination of rare earth impurities in ytterbium oxide by X-ray fluorescence spectrometry

Summary Determination of Kare Earth Impurities in Ytterbium Oxide by X-ray Fluorescence Spectrometry An X-ray fluorescence spectrometric method for the determination of traces of Ho, Er, Tm, Lu and Y oxides in the concentration range of 0.005–1% in ytterbium oxide is developed. The precision at various concentrations of the standards is given. Intensity corrections for line overlaps have been determined.