Synchrotron‐induced EDXRF determination of uranium and thorium in mixed uranium–thorium oxide pellets

Uranium and thorium in their mixed oxides were determined by synchrotron‐induced energy dispersive X‐ray fluorescence (EDXRF) spectrometry. Mixed oxide calibration mixtures containing uranium and thorium in different relative amounts and approximately fixed amount of yttrium were prepared in the form of pellets. The EDXRF spectra of the pellets were measured at the microfocus XRF (BL‐16) beam line of Indus‐2 synchrotron radiation facility (Raja Ramanna Centre of Advanced Technology, Indore, India). Characteristic X‐ray lines U Lα, Th Lα, and Y Kα were used as analyte lines. Calibration plot for the determination of uranium was prepared by plotting amount ratios of U and Y against the intensity ratios of U Lα and Y Kα. Similarly, a calibration plot for thorium analysis was also made. The amounts of uranium and thorium in the sample mixtures prepared in similar way as the calibration mixtures were determined using the aforementioned calibration plots. The precision values obtained for uranium and thorium determinations were found to be 0.3 and 0.2% (relative standard deviation, 1σ), respectively. The EDXRF results deviated from the expected values by 1% for uranium and 0.9% for thorium determinations. These analytical features are much superior compared with laboratory‐based analysis results. Copyright © 2012 John Wiley & Sons, Ltd.     

Application of fission track detection technique for determination of uranium in liquids

A high sensitive (10⁻⁴ ppm) fission track detection technique for determination of uranium in liquids was developed. The technique was applied for the measurement of uranium concentration in extraction phosphoric acid and phosphorus fertilizer, viz., ammophous.     

植物叶片光谱角对土壤铀污染的指示作用

通过在土壤中添加浓度为0(对照组),25,75,125,175,275,375和485μg·g-1的铀,进行5种植物(苎麻、印度芥菜、酸模、甘蓝型油菜、玉米)的盆栽实验,研究了不同生长期的叶片光谱角对土壤铀污染的定性和定量指示作用,分析了定量指示作用与叶片铀含量的关系,并筛选出来在苗期即能反演土壤铀含量的植物,为通过野...     

A total reflection X‐ray fluorescence method for the determination of chlorine at trace levels in nuclear materials without sample dissolution

A total reflection X‐ray fluorescence (TXRF) method for the determination of chlorine at trace levels in nuclear fuel samples is described. Chlorine present in trace concentrations in nuclear fuel materials such as U₃O₈, (U,Pu)C, PuO₂ and Pu‐alloys was first separated from the solid matrix by pyrohydrolysis as HCl and was collected in 5 mM NaOH solution. This solution was analyzed for chlorine by TXRF spectrometry using Cl Kα analytical line excited by W Lα. Cobalt was used as internal standard. The precision for such chlorine determination was found to be within 27% (n = 4) when the analysis was carried out in air atmosphere. This could be improved to 8% by making TXRF measurement in flowing helium atmosphere. The results obtained from TXRF determinations were also compared with those obtained from ion chromatography (IC) and were in good agreement. The collection of distillate during pyrohydrolysis in NaOH helped in counterchecking loss of chlorine during TXRF sample preparation. The average deviation of TXRF‐determined values in helium‐purged TXRF measurements with IC determined values (as chloride) was 15% at a chlorine concentration level in the range of 1–70 µg/mL. Copyright © 2012 John Wiley & Sons, Ltd.     

Pb2+印迹丙烯酸-co-苯乙烯的制备及其吸附性的FAAS法分析

以丙烯酸为功能单体、苯乙烯为骨架单体、Pb2+为模板离子、采用无皂乳液聚合法合成铅离子印迹共聚物(Pb(Ⅱ)-ⅡPs)并采用紫外光谱、傅里叶变换红外光谱和扫描电镜对Pb(Ⅱ)-ⅡPs和非印迹聚合物(NIPs)的表面形貌和结构进行表征.以火焰原子吸收光谱法(FAAS)为检测手段,研究了Pb-ⅡPs对Pb2+的吸附和选择识...     

Ultrasonic-assisted micro solid phase extraction of arsenic on a new ion-imprinted polymer synthesized from chitosan-stabilized pickering emulsion in water,rice and vegetable samples

Pickering emulsion polymerization has been employed for the Ultrasonic assisted-micro solid phase extraction (UA-µSPE) of ultra trace arsenic species by a new magnetic ion imprinted polymer (MIIP) prior to hydride generation atomic absorption spectrometry. 2-acetyl benzofuran thiosemicarbazone (2-ABT) as a new chelating agent and core- shell hydrophobic magnetic nanoparticles was synthesized and the polymerization was carried out at the presence of arsenic – ligand complex, crosslinker, monomer, initiator, stabilizing agent and water-oil emulsion magnetic carrier. In second step, the nanoparticles and polymers were characterized. The analytical parameters such as pH, amount of polymer and ultrasonic time were selected and optimozed by Plackett–Burman and Box–Behnken designs respectively. Linear dynamic range, detection limit and relative standard deviation were 0.01–85.000 µg·L^−l, 0.003 µg·L^−l, and 3.21%, respectively. The proposed preconcentration procedure was successfully applied to the determination of arsenic ion in a wide range of food samples with different and complex matrixes.     

惰气熔融红外吸收法测定高纯金中痕量氧

在采用全杂质元素扣除法进行纯度计算时,痕量氧对高纯金的纯度测定具有明显影响,而以往的杂质扣除法不计算氧等非金属元素,使得纯度测定结果缺乏说服力.通过建立惰气熔融红外吸收法,测量高纯金纯度标准物质中痕量氧含量,同时采用二次离子质谱法进行了方法比对,确保测量结果的可靠性.优化了氧氮氢分析仪的测量参数,确定了最佳工作条件:吹...     

基于X射线透射谱的铀浓度测量方法

在核燃料后处理流程中,需对工艺中的铀浓度进行准确测量。利用X射线管照射铀溶液,通过测量铀的L边界X射线透射谱确定铀浓度。文章设计了铀的L边界X射线透射谱测量系统。通过配制1~200 g·L-1铀标准溶液,建立铀浓度测量工作曲线,并对系统的精密度、准确度和稳定性进行测试。结果表明,铀浓度测量工作曲线线性拟合参数R2=0.999 9;系统对57.004 g·L-1铀溶液测量精密度为0.21%,对38.255 g·L-1铀溶液测量相对误差为0.32%;对2.236 g·L-1铀溶液进行连续测量,99.67%数据落在μ±3 s。     

Trace determination of uranium preconcentrated using graphene oxide by total reflection X-ray fluorescence spectrometry

A new method based on dispersive microsolid phase extraction using graphene oxide (GO) as a solid adsorbent and total reflection X-ray fluorescence (TXRF) spectrometry is proposed for trace determination of uranium. In the developed methodology, a suspension of GO was injected into uranium-spiked multielement solutions including rubidium; after filtration, the membrane filter with collected GO was placed in a small volume of internal standard acid solution and the eluent containing uranium was deposited onto a fluorine resin-coated slide glass, which is a disposable sample stage. Using GO was effective for removal of rubidium from the measurement solution to avoid interference between Rb Kα peak and U Lα peak. The high enrichment factor of 150 enables obtaining uranium detection limits of 0.042, 0.087, and 0.12 μg L⁻¹ for ionic strength of 0.01, 0.1, and 1 mol L⁻¹, respectively. Such low detection limits were obtained by using a benchtop TXRF spectrometer with 5-min measurement. The proposed method is suitable for trace uranium determination in water, including high salinity samples.     

磺胺二甲嘧啶分子印迹聚合物制备与光谱特性

本研究以磺胺二甲嘧啶为模板分子,甲基丙烯酸为功能单体,低温紫外引发聚合制备分子印迹聚合物,用紫外光谱法对磺胺二甲嘧啶与甲基丙烯酸的结合作用及磺胺二甲嘧啶印迹聚合物的静态吸附性能和选择性能进行研究,试验结果表明,溶液中的功能单体与印迹分子之间产生了结合作用;与空白印迹聚合物相比,以甲基丙烯酸为功能单体、磺胺二甲嘧啶为模板的分子印迹聚合物展现了较高的结合容量,与其他结构类似的底物磺胺异唑相比,磺胺二甲嘧啶分子印迹聚合物对磺胺二甲嘧啶模板分子显示出明显的选择性和特异性,静态分配系数K_D可达282.3 mg·mL-1,分离因子α可达3.9,并预测磺胺二甲嘧啶分子印迹聚合物结合机理。分析了甲基丙烯酸、二甲基丙烯酸乙二醇酯和磺胺二甲嘧啶分子印迹聚合物的红外谱图,研究结果表明制备的磺胺二甲嘧啶印迹聚合物中CC双键峰很小,并且功能键羧酸键没有明显变化,经交联聚合得到的聚合物确实存在可以同印迹分子相互作用的化学基团。     

Use of micro‐Raman spectrometry coupled with scanning electron microscopy to determine the chemical form of uranium compounds in micrometer‐size particles

In the frame of nuclear safeguards, knowledge of the chemical form (stoichiometry) of the uranium compounds present in the micrometric particulate material sampled by wiping surfaces in an inspected nuclear facility may point out the industrial process implemented in the installation. Micro‐Raman spectroscopy (MRS) coupled with scanning electron microscopy (SEM) has been used for the first time to analyze micrometer‐size particles of various uranium oxides [UO₂, U₃O₈, UO₃, and UO₄ · 4(H₂O)] deposited on carbon disks. Uranium particles are detected by means of SEM, and Raman analysis is then directly carried out inside the SEM measurement chamber without moving the carbon disk from SEM to MRS. When particles are deposited on appropriate carbon disks (sticky carbon tapes), despite a loss of signal‐to‐noise ratio of about an order of magnitude with regard to the stand‐alone MRS, all uranium oxides are successfully identified in particles by in‐SEM Raman analysis, obtaining similar characteristic bands as the ones obtained with the stand‐alone MRS. Moreover, with the SEM–MRS coupling, particles as small as 1 µm can be analyzed, whereas, without the SEM–MRS coupling, only particles larger than ~5 µm are efficiently analyzed, after localization inside the SEM, transfer of the sample holder into the MRS, and relocation of the particles inside the MRS. Copyright © 2013 John Wiley & Sons, Ltd.     

Assessment of the Nd/U ratio for the quantification of neodymium in UO2

The secondary ion energy spectrum of uranium depends on the experimental conditions, which is a problem for the application of a relative sensitivity factor (RSF) procedure for the measurement of the Nd concentration in UO₂. This is interpreted as due to the dependence of the sputtering and ionisation yields of uranium on the oxidation state of the surface. Three experimental procedures are being tested to cope with this difficulty.     

Ionizing particles may create shockwaves

To find a model that describes the gas diffusion on irradiated polymers (Makrofol KG polycarbonate) the diffusion constants have been measured with argon as diffusion gas. The polymers were irradiated with uranium, gold and lead ions of about 10 MeV/u and ion fluences between 1×10¹⁰ and 4×10¹¹ ions/cm². The ion irradiated probes show two quite different dependencies of the diffusion constant on the ion energy loss. These effects are strongly related to the fluence of the irradiation. In case of low ion fluences, the diffusion constant is up to 8 times higher than that of pristine material. In the probes with high ion fluences we observe a decrease of diffusion constant to half the value of the pristine material. To understand the dependence of the diffusion constant on ion fluences we apply a model of compacting. This model describes the compacting ability of shockwaves arising from latent tracks. A track formation model is suggested. When an ion penetrates the foil it creates shockwaves around its path. These shockwaves put compacting forces on earlier created latent tracks in the same foil.     

Trace determination of uranium in fertilizer samples by total reflection X-ray fluorescence

Uranium is reported to be present in phosphate fertilizers. The recovery of uranium from the fertilizers is important because it can be used as fuel in nuclear reactors and also because of environmental concerns. For both these activities suitable method of uranium determinations at trace levels in these fertilizers are required. Studies have been initiated for such TXRF determination of uranium and the results are reported in the present paper. For TXRF determinations the fertilizer samples were processed with nitric acid and the uranium present in it was removed by solvent extraction using tri-n-butyl phosphate as the extractant. The organic phase containing uranium was equilibrated with 1.5% suprapure nitric acid to bring out uranium in aqueous phase. This aqueous phase was mixed with internal standard Y and the TXRF spectra were measured by depositing samples on float glass supports. The amounts of uranium in four fertilizer samples of Hungarian origin were determined by processing these TXRF spectra. Uranium concentrations in two fertilizer samples were found to be in the range of 4–6 μg/g, whereas two fertilizer samples did not show the presence of uranium. The precision of the TXRF determination of uranium was found to be better than 8% (1σ).     

A comparative study on determination of uranium and thorium in their mixed oxides by EDXRF using tube and radioisotope X‐ray sources

Studies on the matrix effects of uranium and thorium on the determinations of each other in their mixed oxides using energy dispersive X‐ray fluorescence (EDXRF) spectrometry with tube and radioisotope excitations of U Lα and Th Lα are reported. An internal standard method for the determination of uranium and thorium in these mixed oxides is found suitable. Comparison of the analytical results of EDXRF determinations of uranium and thorium using tube and radioisotope excitation sources has been made. The analytical methodology involves preparation of mixed oxide calibration/sample mixtures of uranium and thorium oxides, mixing of internal standard yttrium in these mixtures, pelletizing the mixtures after thorough mixing and grinding using boric acid binder and measuring EDXRF spectra of the specimens thus prepared using Rh X‐ray tube as well as ¹⁰⁹Cd radioisotope source. The samples were analyzed for uranium and thorium on the basis of the calibration plots obtained by plotting the intensity ratios of the analyte and internal standard characteristic X‐ray lines and their corresponding amount ratios. An average precision of 1.2% (1 s RSD) was observed for the determination of U and Th and the results deviated from the corresponding expected values by 3% on average. Due to the refractory nature of thorium oxide, comparatively more grinding time was required for thorium determinations. Copyright © 2011 John Wiley & Sons, Ltd.     

Nanosensors having dipicolinic acid imprinted nanoshell for Bacillus cereus spores detection

Molecular imprinted polymers (MIPs) as a recognition element for sensors are increasingly of interest and MIP nanoclusters have started to appear in the literature. In this study, we have proposed a novel thiol ligand-capping method with polymerizable methacryloylamido-cysteine (MAC) attached to gold–silver nanoclusters, reminiscent of a self-assembled monolayer and have reconstructed surface shell by synthetic host polymers based on molecular imprinting method for recognition. In this method, methacryloylamidoantipyrine–terbium ((MAAP)₂–Tb(III)) has been used as a new metal-chelating monomer via metal coordination–chelation interactions and dipicolinic acid (DPA) which is main participant of Bacillus cereus spores used as a model. Nanoshell sensors with templates give a cavity that is selective for DPA. The DPA can simultaneously chelate to Tb(III) metal ion and fit into the shape-selective cavity. Thus, the interaction between Tb(III) ion and free coordination spheres has an effect on the binding ability of the gold–silver nanoclusters nanosensor. The binding affinity of the DPA imprinted nanoclusters has been investigated by using the Langmuir and Scatchard methods, and the respective affinity constants (K _affinity) determined were found to be 1.43 × 10⁴ and 9.1 × 10⁶ mol L^?1.     

2-(2-喹啉偶氮)-5-二甲氨基苯酚固相萃取光度法测定铀的研究

合成了新试剂2-(2-喹啉偶氮)-5-二甲氨基苯酚(QADMAP),用红外光谱、核磁共振氢谱、质谱、可见吸收光谱和元素分析鉴定了其结构。研究了QADMAP与铀的显色反应,在pH 7.8的三乙醇胺-盐酸缓冲介质中,Triton X-100和氟离子存在下,QADMAP与铀(Ⅵ)和氟离子反应生成1∶1∶1紫色三元稳定络合物,络合物的λ_max＝590 nm,ε＝1.05×105 L·mol-1·cm-1,铀含量在0～20 μg·10 mL-1内符合比尔定律。环境水样中的铀用TBP萃淋树脂固相萃取柱分离和富集后用该方法测定,方法相对标准偏差在2.2%～3.6%之间,标准回收率在94%～105%。     

Ablation of poly(methyl methacrylate) and poly(2-hydroxyethyl methacrylate) by 308, 222 and 193 nm excimer-laser radiation

Data on the ablation of Poly(Methyl MetAcylate) (PMMA) and Poly(2-Hydroxyethyl MetAcylate) (PHEMA) with 0%, 1% and 20% of Ethylene Glycol DiMethAcrylate (EGDMA) as crosslinking monomer by 193, 222 and 308 nm laser radiation are presented. Direct photoetching of PMMA at 308 nm is demonstrated for laser fluences ranging from 2 to 18 J/cm². The ablation rate of PHEMA is lower than the corresponding to PMMA and decreases when the amount of EGDMA increases. The determination of the absorbed energy density required to initiate significant ablation suggests that the photoetching mechanism is similar for all the polymers studied and is a function of the irradiation wavelength. The Beer-Lambert law, the Srinivasan, Smrtic and Babu (SSB) theory and the kinetic model of the moving interface are used to analyze the experimental results. It is shown that only the moving interface theory fits well the etch rate for all the selected polymers at the three radiation wavelengths.     

Characterization and ion-induced degradation of cross-linked poly(methyl methacrylate) studied using time of flight secondary ion mass spectrometry

In this study, a series of random copolymers of methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA) were prepared as surface-initiated polymer (SIP) films on silicon substrates using atom transfer radical polymerization. Positive and negative ion static time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to characterize SIP films with different MMA/EGDMA monomer ratios in an attempt to quantify their surface composition. However, matrix effects in the positive and negative ion modes led to preferential secondary ion generation from the EGDMA monomer and suppression of secondary ions characteristic of the MMA monomer, precluding accurate quantification using standard linear quantification methods. Ion-induced degradation of these films under 5 keV SF₅⁺ bombardment was also examined to determine the effect of cross-linking on the accumulation of ion-induced damage. Increasing incorporation of the EGDMA cross-linker in the SIP films decreased the sputter rate and increased the rate of damage accumulation under extended (>10¹⁴ ions/cm²) 5 keV SF₅⁺ bombardment. Comparison of the ion bombardment data with thermal degradation of cross-linked PMMA suggests that the presence of the cross-linker impedes degradation by depolymerization, resulting in ion-induced damage accumulation. The increased rate of ion-induced damage accumulation with increased cross-link density also suggests that polymers that can form cross-links during ion bombardment are less amenable to depth profiling using polyatomic primary ions.     

不同激发方式对能量色散X射线荧光法测铀的影响

针对能量色散X射线荧光法测铀过程中存在自激发效应对测量结果产生干扰的问题及以往测铀仅使用放射性同位素源作为激发源的测量限制,利用微型X射线对铀矿样品进行自激发效应测量,并分别将109Cd,241Am,微型X光管三种不同激发源测量铀矿样品的结果进行比较分析。结果表明,自激发效应产生的特征X射线峰面积计数仅为有源条件的0.01%以下,属统计涨落范畴,对测量结果的干扰可忽略不计;109Cd源由于其特征射线能量22.11和24.95 keV均在L_α吸收限能量21.75 keV附近,激发光电截面最高,相应的荧光产额也高,故109Cd源相比于241Am源对铀元素的激发效率更高;241Am源测量误差明显大于109Cd源的测量误差,原因是铀的L系能量特征峰与241Am源特征射线26.35 keV的散射峰能量区叠加,造成实测谱线本底偏高;X光管作激发源的铀矿样品中铀含量与化学分析结果之间的误差在10%以内,仅为同位素源激发X射线荧光分析误差的一半,且X光管激发谱峰面积计数值明显大于源激发条件下的峰面积计数,说明X光管作激发源的测铀质量优于源激发模式。