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1.
A study on the applicability of Total Reflection X-ray Fluorescence for the determination of multielements in trace amounts in U3O8 matrix has been made. The calibration of the Total Reflection X-ray Fluorescence spectrometer and the validation of the method were done using multielement standards. The trace elements present in U3O8 standards and samples were determined after separating the U matrix by solvent extraction using tri-n-butyl phosphate and trioctyl phosphine oxide as extractants. From the aqueous phase the elements K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Br, Rb, Sr, Y, Zr, Pb and Ba, etc., were determined by Total Reflection X-ray Fluorescence using Ga as an internal standard. An intercomparison of the Total Reflection X-ray Fluorescence determined concentrations of the trace elements specific to nuclear fuel, e.g. Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn in U3O8 standards/samples with certified concentrations for these elements in U3O8 standards and Inductively Coupled Plasma Atomic Emission Spectroscopy determined concentrations in real U3O8 samples was also made. The method shows a precision and accuracy better than 5% (1σ) for most elements in concentration range of ng/mL with a sample size of 10 μL.  相似文献   

2.
Summary An atomic absorption spectrometric method has been developed for the determination of chromium, cobalt, copper, manganese and nickel in U3O8 by electrothermal atomization of 5 mg powder samples. Nanogram amounts of all the elements can be estimated with a precision ranging between 7–12%. The non-specific absorption due to U3O8 for these measurements is negligible. The use of graphite powder with U3O8 in equal or double the sample amount improves sensitivity for the analyte element and prolongs the life of the atomizer.
Direkte AAS-Bestimmung von Co, Cr, Cu, Mn und Ni in U3O8 durch elektrothermische Atomisierung
Zusammenfassung Das entwickelte AAS-Verfahren geht von pulverförmigen 5mg-Proben aus. Nanogramm-Mengen der genannten Elemente können mit einer Genauigkeit im Bereich von 7–12% bestimmt werden. Die durch U3O8 verursachte unspezifische Absorption ist zu vernachlässigen. Durch Graphitzusatz (in der gleichen oder doppelten Menge der Probe) wird die Empfindlichkeit der Bestimmung verbessert und die Lebensdauer des Atomizers verlängert.
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3.
Summary An Atomic Emission Spectrometric (AES) method has been developed for the direct determination of twenty-two metallic elements at trace concentrations in thorium oxide. The method is based on the use of a d.c. arc — carrier distillation technique with 12% composition of a mixed carrier, viz. AgCl+SrF2 in 5:1 proportion, and is equally applicable to both volatile and refractory analytes. A direct reading emission spectrometer with computerised data acquisition and processing facility has been used in these studies. The standardisation procedure includes study of volatilisation/excitation characteristics of the analyte elements to optimise choice and proportion of the carrier and signal integration time apart from optimisation of other experimental parameters such as arc current, viewing position of the arc plasma, sample charge etc. The detection limits for the analytes lie in the range 0.1–50 ppm while the precision of determinations is better than 15% for most of the elements as evaluated from the repetitive analyses of spiked samples.  相似文献   

4.
Summary A new approach for the trace metal assay of U3O8 powder has been described. The carrier distillation technique used for selective volatilization of trace metals in U3O8 with d.c. arc excitation is adapted for the release of analytes from the solid sample into the ICAP source by inductively heating the sample. The experimental parameters have been optimised for the direct determination of Cd, Cu, K, Na, Ni and Pb. The performance of the method developed here is tested for the precision and accuracy of determinations by analysing spiked U3O8 samples and NBL U3O8 reference standards (standard deviation 2–9%). The method appears promising to be developed as a highly precise analytical optical emission spectrometric method as it adds to the ingenuity of the carrier distillation method, the advantages of ICAP.
Bestimmung von Metallspuren in U3O8-Pulver durch Trägerdestillation/ICAP
Zusammenfassung Das Trägerdestillationsverfahren zur selektiven Verdampfung von Spurenmetallen in U3O8 im Gleichstrombogen wurde mit induktiver Probeerhitzung für ICAP angepaßt. Die experimentellen Parameter wurden für die direkte Bestimmung von Cd, Cu, K, Na, Ni und Pb optimiert. Die Leistungsfähigkeit des Verfahrens wurde mit Hilfe von Proben mit bestimmten Zusätzen sowie mit zertifiziertem Referenzmaterial überprüft (Standardabweichung 2–9%). Durch die Verbindung der Vorteile von Trägerdestillation und ICAP bietet sich eine Methode von hoher Präzision.
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5.
本文采用国产部件组装了一套ETV-ICP-AES仪器体系,对装置的连接及操作参数进行优化。深入系统地考察了分析物的蒸发过程和传输过程,提出了难熔元素的蒸发和传输机理。研究了ETV-ICP-AES中基体效应,提出了以聚四氟乙烯为氟化剂,氟化辅助ETV-ICP-AES测定难熔元素的新方法,应用于环境和生物标样中痕量元素分析,获得满意结果。  相似文献   

6.
A study of the factors which affect the gravimetric determination of uranium in uranyl nitrate is described. In the gravimetry of uranium, the U3O8 (weighing form) produced by ignition is usually assumed to deviate <0.02% from theoretical composition; and elemental impurities are assumed to form common oxides within the U308 matrix. It is shown that these assumptions are incorrect. Ignition temperature and time affect U3O8 stoichiometry. Ignitions of uranyl nitrate for 1–3 h at 850° produce U3O8 that deviates as much as 0.15% from stoichiometric U3O8; deviations are negligible when uranyl nitrate is ignited at 1000° for 2 h. Elemental impurities, particularly calcium and phosphorus, affect the composition of U3O8 formed in the ignition of uranyl nitrate. A variety of impurity complexes such as uranates and phosphates are found within the U3O8 matrix. Formation of these impurity complexes depends on the elements present, their concentration, and ignition temperature. Therefore, in the gravimetric determination of uranium in uranyl nitrate, the effects of ignition parameters and nonvolatile impurities must be considered in order to obtain accurate uranium determinations.  相似文献   

7.
In order to examine the capability of energy dispersive X-ray fluorescence spectrometry for the determination of some common metallic impurities in nuclear grade U3O8 matrix, a series of synthetic U3O8 standards, containing impurities such as Ca, Co, Cr, Cu, Fe, Mn, Mo, Ni ,V, W and Zn in the concentration range, 100–1000 μg/g, were prepared. Using these standards, calibration curves were set up for different elements after optimizing the spectrometer parameters. Two synthetic samples and five reference standards obtained through an inter-laboratory comparison exercise within analytical laboratories of Department of Atomic Energy, India were analyzed to evaluate the performance of the newly developed analytical methods. The estimates for most of the analytes were in good agreement with the added amounts. The method is fast, since it requires no chemical treatment. The method has good precision for the analytes determined.  相似文献   

8.
A new method for the determination of trace amounts of 14 rare earth elements in high purity Y2O3 using fluorination assisted electrothermal vaporization inductively coupled plasma atomic emission spectrometry with slurry sampling was developed. A polytetrafluoroethylene (PTFE) emulsion was used as a fluorinating reagent to promote the vaporization of the analytes from graphite furnace. The main factors affecting analytical signals were investigated systematically. The interference of matrix could be minimized in the presence of PTFE. Under optimum conditions, the detection limits for rare earth elements were 0.032 ng~2.52 ng and the relative standard deviations were in the range of 1.4% to 4.3%. The proposed method was applied to the direct analysis of high purity Y2O3 powder with satisfactory results.  相似文献   

9.
A new method for the determination of trace amounts of 14 rare earth elements in high purity Y2O3 using fluorination assisted electrothermal vaporization inductively coupled plasma atomic emission spectrometry with slurry sampling was developed. A polytetrafluoroethylene (PTFE) emulsion was used as a fluorinating reagent to promote the vaporization of the analytes from graphite furnace. The main factors affecting analytical signals were investigated systematically. The interference of matrix could be minimized in the presence of PTFE. Under optimum conditions, the detection limits for rare earth elements were 0.032 ng∼2.52 ng and the relative standard deviations were in the range of 1.4% to 4.3%. The proposed method was applied to the direct analysis of high purity Y2O3 powder with satisfactory results. Received: 19 June 1999 / Revised: 10 December 1999 / Accepted: 16 December 1999  相似文献   

10.
The paper deals with homogeneous magnetic fields and added chemical substances both affecting the spectrochemical results obtained in arc excitation studies. The influence of a homogeneous magnetic field on the total intensity of lines of various analysis elements (Hg, Zn, Ga, Tl) in graphite has been examined. Furthermore, the axial and radial distributions of line intensities in arc plasma were determined. Parameters used were the magnetic field strength (0, 0.01, 0.02, 0.04 T) and the physical data of the analysis elements. It was found that the effect of the magnetic field varies with the ionization potential of the elements involved, their atomic mass and the strength of the magnetic field applied. A non-destructive method of measuring was introduced for studying the effects of a homogeneous magnetic field on the rates of evaporation. The results showed increased evaporation rates in presence of magnetic fields as a function of the evaporation heat of the elements involved. Effects of Ga2O3 additive on the line intensities of impurity elements are governed by the Ga2O3 concentration and the ionization potential of the elements examined.  相似文献   

11.
The determination was studied of Al, B, Be, Cd, Ca, Co, Cu, Mg, Mn, Mo, Pb, Si, Sn, V, Cr, Ni, and Fe as trace level impurities in uranium compounds by ICP-AES after extraction of uranium with three different mixtures of di-(2-ethyl-hexyl) phosphate (D2EHP) and tri-(2-ethyl-hexyl)-phosphate (T2EHP) in solvents like toluene, carbon tetrachloride, hexane and cyclohexane. The study was carried out in presence of different concentrations of HCl and HNO3. A single extraction with D2EHP in cyclohexane using nitric acid as matrix was sufficient to reduce the U3O8 concentration from 100 g/l to 100 g/ml. The ICP-AES instrumentation applied, allowed the determination of metal concentrations ten-times lower than those usually found in nuclear grade U3O8. To check the efficiency of the extraction and the accuracy of the proposed method, Certified Reference Materials were used in the dissolution and extraction steps. The method described can be used for the determination of trace metals in nuclear grade U3O8.  相似文献   

12.
High-performance liquid chromatography coupled with graphite furnace atomic absorption spectroscopy (HPLC? GF AA) gives element-specific detection of environmental samples containing trace amounts of organotin or organolead species. The direct GF AA of organotin and organolead species is subject to errors arising primarily from loss of analyte prior to atomization, probably through the formation of refractory carbides and of compounds or complexes that are volatile at low temperatures. Examples abound in the literature of signal suppression in the GF AA of organometallic species in environmental samples, and several furnace tube modifications have been developed to overcome this suppression. Here, the analyte and a modifier are co-pipetted into a conventional furnace tube, from either a solution of analyte or an HPLC effluent. Oxides of transition metals (e.g. chromium, manganese, or tungsten) are shown to enhance both tin and lead signals, whereas chlorides do not, suggesting the low-temperature formation of relatively involatile metal oxides or volatile metal chlorides, respectively. In the absence of modifier, GF AA signal intensities decrease consecutively for equal quantities of mono-, di-, tri- and tetra-butyltin species, but are nearly equal for the first three in the presence of complexing dichromate (Cr2O72?). The lesser signal increase for tetrabutyltin indicates a dissimilar low-temperature complexation chemistry for the fully ligated neutral organometal to that for the ligated ions. similar results are demonstrated in post-column addition of a matrix modifier to effluent containing either organotin or organolead species.  相似文献   

13.
Lithium assisted electrochemical reduction of U3O8 in the room temperature ionic liquid (RTIL), N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf2), was studied to explore the feasibility of using RTILs for direct electrochemical reduction of uranium oxide at near ambient temperature. The electrochemical behavior of Li+ in MPPiNTf2 at stainless steel electrode was investigated by cyclic voltammetry and chronoamperometry. The cyclic voltammogram of LiNTf2 in MPPiNTf2 at 373 K consisted of a surge in cathodic current occurring at a potential of −2.8 V (vs. Fc/Fc+) due to the reduction of Li(I) to metallic form. The nucleation phenomenon observed in the voltammogram was investigated by chronoamperometry. Electrodeposition of metallic lithium on U3O8 particles contained in a stainless steel (SS) basket was carried out to examine the feasibility of reducing U3O8 to metallic form. The results are discussed in this paper.  相似文献   

14.
 A sensitive method has been developed for the sequential determination of V, Mn, Fe, Co, Ni, Cu, Zn, Mo and Sb in sea water using inductively coupled plasma mass spectrometry (ICP-MS) after electrothermal vaporization of their dithiocarbamate complexes in methyl isobutyl ketone (MIBK). After complexion with sodium diethyldithiocarbamate (NaDDTC), all trace analyte elements were simultaneously separated from sea water matrix and concentrated 20 fold in a single extract of MIBK, followed by introduction of 10 μL of the extract into argon plasma using a pyrolytic graphite rod electrothermal vaporizer (ETV). Sensitivity enhancement due to chemical modification using a mixed modifier of Pd(NO3)2-Mg(NO3)2 was observed for all the elements. The limits of detection ranged from 2 ng/L for Co to 329 ng/L for V. For replicate determinations of the elements in sea water, the repeatability was within 10% (as a coefficient variation), except for V (12.8%). The recovery test performed on a sea water sample resulted in a range value from 87% for Sb to 119% for V. The method has been successfully applied to sea water samples collected from the surface to the depth of 5000 m at a sampling station in the northwest Pacific Ocean. Received: 1 July 1996/Revised: 24 September 1996/Accepted: 25 September 1996  相似文献   

15.
 A sensitive method has been developed for the sequential determination of V, Mn, Fe, Co, Ni, Cu, Zn, Mo and Sb in sea water using inductively coupled plasma mass spectrometry (ICP-MS) after electrothermal vaporization of their dithiocarbamate complexes in methyl isobutyl ketone (MIBK). After complexion with sodium diethyldithiocarbamate (NaDDTC), all trace analyte elements were simultaneously separated from sea water matrix and concentrated 20 fold in a single extract of MIBK, followed by introduction of 10 μL of the extract into argon plasma using a pyrolytic graphite rod electrothermal vaporizer (ETV). Sensitivity enhancement due to chemical modification using a mixed modifier of Pd(NO3)2-Mg(NO3)2 was observed for all the elements. The limits of detection ranged from 2 ng/L for Co to 329 ng/L for V. For replicate determinations of the elements in sea water, the repeatability was within 10% (as a coefficient variation), except for V (12.8%). The recovery test performed on a sea water sample resulted in a range value from 87% for Sb to 119% for V. The method has been successfully applied to sea water samples collected from the surface to the depth of 5000 m at a sampling station in the northwest Pacific Ocean. Received: 1 July 1996/Revised: 24 September 1996/Accepted: 25 September 1996  相似文献   

16.
Zusammenfassung Es wurde die Empfindlichkeit der emissionsspektrographischen Doppelbogenanalyse auf Spurenelemente im U3O8 mit Zusätzen von Li2CO3, PbF2 und NaCl untersucht. Li2CO3 eignet sich vor allem für den Nachweis von Elementen mit niedrig siedenden Oxyden wie Pb, Ag, Cd, Ga, Ge, In, Pb, Sn, Sb, Tl und Zn. Durch Zusatz von PbF2 wird unter anderem B, Be, Al und Si bevorzugt zum Verdampfen gebracht. Der Zusatz von NaCl gestattet den empfindlichen Spurennachweis von Elementen mit niedrig siedenden Oxyden, sowie einiger schwerer flüchtiger Elemente, die flüchtige Chlorverbindungen eingehen, wie z. B. Fe, Co. Ni, V und Mo. Mit Prismenspektrographen wurden Nachweisgrenzen bis zu 0,01 ppm erreicht.
Summary A study was made of the sensitivity of the emission spectrographic double arc analysis of trace elements in U3O8 with additions of Li2CO3, PbF2 and NaCl. Li2CO3 is especially suitable for the detection of elements with lowboiling oxides such as Pb, Ag, Cd, Ga, Ge, In, Pb, Sn, Sb, Tl, Zn. The addition of PbF2 favors the volatilization among others of B, Be, Al, Si. The addition of NaCl permits the sensitive trace detection of elements with low-boiling oxides as well as of several elements which do not volatilize so readily, which form volatile chlorine compounds, for example Fe, CO, Ni, V and Mo. Detection limits as low as 0,01 ppm were obtained with prism spectrographs.

Résumé On a étudié la sensibilité de l'analyse par spectrographie d'émission par arc double sur des éléments à l'état de traces dans U3O8, avec additions de Li2CO3, PbF2 et NaCl. Li2CO3 convient surtout pour la recherche des éléments dont les oxydes s'évaporent à basse température, comme Pb, Ag, Cd, Ga, Ge, In, Sn, Sb, Tl et Zn. Par addition de PbF2, on vaporise entre autres B, Be, Al et Si. L'addition de NaCl permet la recherche de traces d'éléments dont les oxydes se vaporisent à basse température ainsi que de quelques éléments plus difficilement volatils qui se transforment en composés chlorés volatils, comme par exemple Fe, Co, Ni, V et Mo. Avec des spectrographes à prisme on peut atteindre la limite de recherche de 0,01 ppm.
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17.
An electrothermal atomic absorption method (ETAAS) for the direct determination of trace elements (Cd, Cr, Cu, Mn, Se) both in blood fractions (erythrocytes, plasma and lymphocytes) and whole blood was developed. Zeeman background correction and graphite tubes with L’vov platforms were used. Samples were ¶diluted with HNO3/Triton X-100 and pipetted directly ¶into the graphite tube. Ashing, pretreatment and atomization steps were optimized carefully for the different fractions and elements applying different matrix modifiers ¶for each element. For the lymphocyte fraction a multi-fold injection technique was applied. Low detection limits ¶of the ETAAS method (Cd 0.13 μg/L, Cr 0.11 μg/L, ¶Cu 0.52 μg/L, Mn 0.13 μg/L, Se 0.7 μg/L of whole blood) combined with small quantities of sample necessary for analysis allow determination of trace elements in this matrix. Verification of possible differences in the trace element status of humans was performed with statistical significance (P < 0.05). In addition, a contribution to the determination of normal values of essential elements was achieved. The method was applied for determination of trace elements in human blood and blood fractions of two groups (n = 50) different in health status.  相似文献   

18.
A novel method for the determination of trace rare earth impurities in ZrO2 powder has been developed based on electrothermal vaporization inductively coupled plasma atomic emission spectrometry. A polytetrafluoroethylene slurry was used as a fluorinating reagent to convert both the matrix (Zr) and the analytes (rare earth elements) into fluorides with different volatilities at a high temperature in a graphite furnace. The more volatile ZrF4 was removed in-situ by selective vaporization prior to the determination of the analytes, removing matrix spectral interferences. Under optimum operating conditions, the absolute detection limits of the analytes varied from 0.04 ng (Yb) to 0.50 ng (Pr) with relative standard deviations less than 5%. The recommended approach has been successfully applied to the determination of trace rare earth impurities (La, Pr, Eu, Gd, Ho and Yb) in ZrO2 powder and the results were in good agreement with those obtained by pneumatic nebulization inductively coupled plasma atomic emission spectrometry after the separation of the matrix using a solvent extraction procedure.  相似文献   

19.
In order to determine the operating conditions of an uranium reduction process with U3O8-Li-LiCl system, the operating conditions have been evaluated in thermodynamic aspects and the results were experimentally confirmed in this study. All the reduction experiments were conducted in an argon atmospheric glove box, and the resultant degree of reduction was determined by analyzing the product using XRD and TGA. In the results of this study, a reduction yield greater than 95% is achieved within about 3 hours of reaction. The effects of the added quantity of Li and LiCl to the reduction yield of U3O8 and the preferential removal of several metal oxides accompanying U3O8 in the course of reduction were discussed. For a greater reduction of U3O8, an additional 20% of Li is required when compared to the stoichiometric composition. The proper composition of LiCl is about 75% based on the weight of U3O8 charged.  相似文献   

20.
Using active carbon-silica gel as adsorbent and sodium diethyldithiocarbamate (NaDDTC) as chelating reagent in a flow injection system, an ICP-AES method has been developed for preconcentration and determination of trace metallic elements in high purity rare earth oxides. The experimental parameters such as pH, flow rate, amount of adsorbent, length of reaction coil and eluent acidity were optimized. At pH 4.6 Al,Cr,Cu,Fe,Pb,V,Zn could be preconcentrated, and subsequently determined by ICP-AES. This method can eliminate matrix effects. Its enrichment factors were 8.1–12.6 with detection limits in the ng/mL range and RSD of 2.3–5.0. This method was applied to the analysis of high purity of La2O3 and Eu2O3 with satisfactory results. Received: 24 April 1997 / Revised: 22 September 1997 / Accepted: 7 October 1997  相似文献   

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