Radioisotope X-ray fluorescence analysis of some elements in fly ash of Afsin-Elbistan power plants

Energy dispersive X-ray fluorescence technique was used for the determination of As, Sr, Mo, Ba, In and Ce in fly ash Afsin-Elbistan power plants using the standard addition method. An annular²⁴¹Am source was employed for excitation of the K shell of the elements.     

Total reflection X-ray fluorescence analysis of fly ash from Bulgarian coal-fired power plants

The contents of Cl, Ca, K, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Rb, Sr, Ba and Pb in raw coal fly ash from five Bulgarian power plants were determined by total reflection X-ray fluorescence (TXRF), using gallium as the internal standard. The samples were analysed as in slurry form in Triton? X-114. The experimental parameters, such as grain size, concentrations of fly ash slurry and excitation time were optimised. For validation of the method, the certified reference material BCR-176R fly ash was used. The precision of the results obtained is characterised by a relative standard deviation of approximately 10%. The resulting data confirm the suitability of TXRF for the simultaneous determination of major, minor and trace elements in coal fly ash samples. Further advantages provided by TXRF are easy sample preparation (no sample dissolution) and the small sample amount required for analysis.     

Capability and limitations of the determination of sulfur in inorganic and biological matrices by total reflection X-ray fluorescence spectrometry

The capability and limitations of TXRF were explored for the determination of the light element sulfur in inorganic and biological samples. The recovery rates of sulfur were measured with tungsten L-radiation in the dry residues of various sulfates and sulfur containing amino acids with a sulfur concentration ranging from 0.5 to 20 mg/l. Furthermore, the surface topography of the dry residues of the samples was investigated by scanning electron microscopy (SEM) and their thickness profiles were recorded by an Alpha-Step. The results show that the reliable determination of sulfur in inorganic samples depends on the cation involved. Alkali sulfates tend to form bulky residues which disturb the determination of sulfur distinctly due to absorption effects of the soft sulfur K radiation. In this case the use of smoothing detergents like 1% HF, 1% malic acid and 2% hydrazine hydrate is necessary for the determinations with reasonable accuracy (tolerance range: ±10% of the recovery rate). The results for the biological samples measured agree well with the expected values. The investigations lead to the conclusion that TXRF combined with a proper sample preparation is well suited for the determination of sulfur in samples of various matrices in a wide range of concentrations.     

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.     

Rapid determination of coal ash content by means of X-ray fluorescence and scattering

Determination of the ash content of coal by measuring secondary radiation of samples in three different energy ranges is presented. A simple equipment with proportional counter and a²³⁸Pu source of primary X-rays was used. The experiments were carried out using 72 coal samples from various deposits. A mean standard deviation of about 2.5% of ash content was achieved.     

Element determination in medieval soil samples by total reflection X-ray fluorescence analysis

An aqua regia extraction procedure for heavy metals in soils optimised for total reflection X-ray fluorescence analysis is presented. The procedure is applied to 92 soil samples of medieval layers from the city area of Dortmund. Sixteen elements (P, S, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Ag, Sn, and Pb) were used to characterise 17 sample sites. The results are projected onto the medieval urban structure of Dortmund. Two sites loaded with non-ferrous heavy metal could be detected and correlated with archaeological data. The efficiency and repeatability of the proposed extraction procedure is discussed.     

Trace element determination in thorium oxide using total reflection X-ray fluorescence spectrometry

Applicability of Total Reflection X-ray Fluorescence (TXRF) spectrometry for the determination of trace metals at concentration of µg/g level in thorium oxide was studied. The TXRF spectrometer was calibrated using a multielement standard solution and the method was validated by analyzing another multielement standard solution. Sample preparation conditions were optimized for the TXRF determinations of trace metals in thorium oxide. The elements K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Ba and Pb present in thorium oxide standards were determined after dissolving them in HNO₃/HF mixture and separating the bulk matrix, thorium, by solvent extraction using tri-n-butyl phosphate (TBP) and tri-n-octyl phosphine oxide (TOPO) as extractants. A comparison of TXRF determined concentrations of trace elements Ca, V, Cr, Mn, Fe, Ni and Cu with the certified values shows that TXRF determined concentrations have an RSD of 20% (1 s for n = 4) and are within an agreement of 20% of the certified values in most of the cases.     

X-ray fluorescence determination of sulfur and other elements in customs control of oil and liquid oil products

Results of an X-ray fluorescence determination of sulfur and other elements in oils and liquid oil products are presented, obtained using a Spectro-Xepos energy-dispersive spectrometer with the excitation of the fluorescence spectrum immediately in the liquid samples under investigation. It is shown that the amount of trace elements considerably varies not only in different types of oil products, but also in different samples of the same product. An experimental evaluation of the metrological characteristics of the determination of sulfur in oil products showed that they met the requirements of GOST (Russian State Standard) R 50442-92 Oil and Oil Products: X-ray Fluorescence Method for Determining Sulfur.     

Quantitative determination of cadmium in polyethylene using total reflection X-ray fluorescence (TXRF) spectroscopy

A new application of total reflection X-ray fluorescence (TXRF) spectroscopy was tested for its use in the quantitative determination of element mass fractions (Z ≥ 12) in solid polyethylene samples. The experiments were conducted with four polyethylene reference materials from the Institute for Reference Materials and Measurements (IRMM) with cadmium mass fractions in the range from 40 to 400 mg/kg (VDA 001–004). Samples from each reference material were transferred as thin films straight onto quartz glass discs commonly used for TXRF analysis. Precision, accuracy and capability of the method are discussed on the basis of the current results and recent experiences with real samples. The method appears to be suitable for tasks in forensic science and polymer analysis.     

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.     

Rapid determination of platinum plasma concentrations of chemotherapy patients using total reflection X-ray fluorescence

A fast and simple method using Total Reflection X-ray Fluorescence has been developed for the determination of platinum plasma concentrations of patients undergoing chemotherapy with Pt-bearing drugs. Avoiding chemical digestion, micro liter amounts of blood plasma are employed using Compton peak standardization and the use of matrix-matched spiked samples with known amounts of platinum for spectrometer sensitivity determination. The analytical results with the proposed procedure are compared to values obtained with Graphite Furnace Atomic Absorption Spectrometry obtaining values of comparable accuracy and precision. Measurements of the time course of the Pt plasma concentration in single-dose treatments, and of the achieved plasma concentration of multiple infusion treatments demonstrate the potential usefulness of the method for pharmacokinetic studies or for routine optimization of Pt chemotherapy treatments.     

Separation of matrix absorption and enhancement effects in the determination of sulfur in sea water by X-ray fluorescence

The analytical utility of chloranil-loaded polyurethane foam in a syringe column was investigated. A rapid method for the determination of micro and semimicro amounts of cerium(IV), vanadium(V) and iron(III) by means of this redox “pulsed” column has been developed. The effects of number of pulses, temperature and concentration of metal ion in solution on the reduction efficiency of the proposed pulsed column were critically studied. Analyses for different concentrations of Ce(IV), V(V) and Fe(III) were successfully carried out with an average relative error of ±2.2%.     

The use of X-ray fluorescence (XRF) analysis in predicting the alkaline hydrothermal conversion of fly ash precipitates into zeolites

The use and application of synthetic zeolites for ion exchange, adsorption and catalysis has shown enormous potential in industry. In this study, X-ray fluorescence (XRF) analysis was used to determine Si and Al in fly ash (FA) precipitates. The Si and Al contents of the fly ash precipitates were used as indices for the alkaline hydrothermal conversion of the fly ash compounds into zeolites. Precipitates were collected by using a co-disposal reaction wherein fly ash is reacted with acid mine drainage (AMD). These co-disposal precipitates were then analysed by XRF spectrometry for quantitative determination of SiO₂ and Al₂O₃. The [SiO₂]/[Al₂O₃] ratio obtained in the precipitates range from 1.4 to 2.5. The [SiO₂]/[Al₂O₃] ratio was used to predict whether the fly ash precipitates could successfully be converted to faujasite zeolitic material by the synthetic method of [J. Haz. Mat. B 77 (2000) 123]. If the [SiO₂]/[Al₂O₃] ratio is higher than 1.5 in the fly ash precipitates, it favours the formation of faujasite. The zeolite synthesis included an alkaline hydrothermal conversion of the co-disposal precipitates, followed by aging for 8 h and crystallization at 100 °C. Different factors were investigated during the synthesis of zeolite to ascertain their influence on the end product. The factors included the amount of water in the starting material, composition of fly ash related starting material and the FA:NaOH ratio used for fusing the starting material. The mineralogical and physical analysis of the zeolitic material produced was performed by X-ray diffraction (XRD) and nitrogen Brunauer-Emmett-Teller (N₂ BET) surface analysis. Scanning electron microscopy (SEM) was used to determine the morphology of the zeolites, while inductively coupled mass spectrometry (ICP-MS), Fourier transformed infrared spectrometry (FT-IR) and Cation exchange capacity (CEC) [Report to Water Research Commission, RSA (2003) 15] techniques were used for chemical characterisation. The heavy and trace metal concentrations of the zeolite products were compared to that of the post-synthesis filtrate and of the precipitate materials used as Si and Al feed stock for zeolite formation, in order to determine the trends (increase or decrease) and ultimate fate of any toxic metals incorporated in the co-disposed precipitated residues.     

ICP-MS multielement determination in fly ash after microwave-assisted digestion of samples

A microwave assisted digestion procedure has been developed for dissolution of fly ash samples prior to the inductively coupled plasma-mass spectrometric determination of their elemental composition. The developed methodology was validated by carrying out the analysis of two high-silicate containing reference materials (CRM 134R sewage amended soil and NIES JR 1 rock) and by means of the comparison between results found by microwave-assisted digestion and ICP-MS of fly ash samples with those found by neutron activation analysis (NAA) for Sb, Cs, Cr, Co, Fe, U and Zn determination. The method developed can be recommended for routine multielement analysis of fly ash.     

催化褪色光度法测定粉煤灰中痕量钼

在pH11.0的Na2CO3 NaHCO3缓冲溶液中,痕量钼(Ⅵ)对H2O2氧化偶氮胭脂红B的褪色反应具有强烈的催化作用,据此建立了一种测定痕量钼(Ⅵ)的催化光度法的新方法。方法的检出限为2.04×10-2μg/L,线性范围为0～6.0μg/L,该法已应用于粉煤灰中痕量钼的测定。     

The spectrographic determination of total barium in bone ash

Samples of bone ash are mixed with graphite and anhydrous copper sulphate as spectrographic buffer and lanthanum oxide as internal standard. The mixture is pressed into 30-mg pellets and burnt in a d.c. arc surrounded by a mantle of oxygen and argon. The spectra are evaluated by non-recording microphotometry. The effective concentration range is 2–25 p.p.m. of barium in the ash, and the coefficient of variation is 8% for single exposures at the 8-p.p.m. level     

X-ray fluorescence determination of niobium in iron-niobium alloys

Summary An X-ray fluorescence method is described for the determination of niobium in iron-niobium alloy in the concentration range from 0.1–2% of niobium. The sample is dissolved in a mixture of nitric and hydrofluoric acid and is converted to a stable oxide. This oxide is uniformly ground with boric acid and a weighed quantity of it is pressed into a circular pellet. The pellet is exposed to an X-ray beam from a tungsten target. The resulting fluorescent X-ray beam is dispersed using an LiF crystal and the intensity of the NbK -line is measured by a scintillation counter. A set of synthetic standards covering the above range is prepared using highpurity chemicals and a working curve for the estimation of niobium is established. The accuracy of the method is checked by analysing synthetic samples. The standard deviation of the method ranged from 0.5% at 5% Nb to 3.5% at 0.1% of Nb concentration.

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Röntgenfluorescenzspektroskopische Niobbestimmung in Eisen-Niob-Legierungen

Zusammenfassung Die Methode erlaubt eine Niobbestimmung im Konzentrationsbereich von 0,1–2% Niob. Die Probe wird in Salpetersäure/Flußsäure gelöst und in ein stabiles Oxid überführt, das mit Borsäure vermahlen und zu einer Tabelette gepreßt wird. Zur Röntgenfluorescenzmessung (W-Röhre, LiF-Kristall) wird die NbK -Linie herangezogen (Szintillationszähler). Mit Hilfe hochreiner Reagentien wurden synthetische Standards für den genannten Konzentrationsbereich hergestellt. Die Genauigkeit wurde mit Hilfe synthetischer Proben überprüft (Standardabweichung 0,5 % bei 5% Nb, 3,5% bei 0,1% Nb).