Application of laser ablation inductively coupled plasma mass spectrometry for the isotopic analysis of single uranium particles

The paper describes the application of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for the isotopic analysis of individual uranium-oxide particles. The procedure developed is suitable for the accurate measurement of ²³⁴U, ²³⁵U, ²³⁶U and ²³⁸U isotopes in single actinide particles with lateral dimensions down to 10 μm. The ²³⁵U/²³⁸U isotope ratios can be obtained with a precision of a few percent relative standard deviation using a single collector ICP-MS instrument. The precision could be improved by the use of slow ablation and by taking several LA-ICP-MS replicate spectra on the same particle investigated. For the minor isotopes use of higher mass resolution (R = 4000) was necessary in some cases to avoid spectral interferences. The technique developed offers a rapid and accurate possibility for the isotopic composition determination of uranium-containing individual particles in environmental and safeguards samples.     

Bulk analysis by IR laser ablation inductively coupled plasma atomic emission spectrometry

Two laser ablation systems dedicated to bulk analysis were evaluated for steel and PVC samples, using inductively coupled plasma atomic emission spectrometry detection. These systems were characterized by the use of a Nd:YAG laser operating at 1064 nm, the absence of observation device and a large laser spot size. The 1064 nm wavelength was selected to avoid the use of frequency-multiplying optics, and to be less critical to the sampling position. Calibration graphs and limits of detection are given for both types of materials. LODs were in the range 3–120 μg/g for steel, and in the range 0.07–15 μg/g for PVC. In the case of steel samples, similar calibration graph slopes were obtained between polished and unpolished samples.     

Bulk analysis by IR laser ablation inductively coupled plasma atomic emission spectrometry

Two laser ablation systems dedicated to bulk analysis were evaluated for steel and PVC samples, using inductively coupled plasma atomic emission spectrometry detection. These systems were characterized by the use of a Nd:YAG laser operating at 1064 nm, the absence of observation device and a large laser spot size. The 1064 nm wavelength was selected to avoid the use of frequency-multiplying optics, and to be less critical to the sampling position. Calibration graphs and limits of detection are given for both types of materials. LODs were in the range 3-120 microg/g for steel, and in the range 0.07-15 microg/g for PVC. In the case of steel samples, similar calibration graph slopes were obtained between polished and unpolished samples.     

Determination of uranium in organic solutions by inductively coupled plasma atomic emission spectrometry

The determination of uranium in organic solutions by inductively coupled plasma atomic emission spectrometry is reported. The conditions for achieving plasma stability were determined as well as the optimum conditions (RF power, observation height and argon flow) of a spectrometer for analysis of U(II) 367.007 nm in three organic solvents, xylene, kerosine and benzene. The effects of RF power and observation height on signal-to-back-ground ratio and the detection limits are considered. Spectral interferences due to CN band are discussed.A part of this work was presented at the Second Karlsruhe International Conference on Analytical Chemistry in Nuclear Technology Karlsruhe, FRG, June 5–9, 1989.     

Trace analysis of uranium ore concentrates using laser ablation inductively coupled plasma mass spectrometry for nuclear forensics

Journal of Radioanalytical and Nuclear Chemistry - We present a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method for trace-element analysis of uranium ore concentrates...     

Development of methodologies for the analysis of uranium ores by k 0-instrumental neutron activation analysis and inductively coupled plasma atomic emission spectrometry

Journal of Radioanalytical and Nuclear Chemistry - Analytical methodologies were developed for the determination of elemental contents in four uranium ore samples (S-8, S-12, S-13 and S-17) from...     

Combination of flow-injection techniques with atomic spectrometry in agricultural and environmental analysis

Combinations of flow-injection techniques with flame atomic absorption spectrometry (a.a.s.) and inductively-coupled plasma/atomic emission spectrometry (i.c.p./a.e.s.) are reviewed in the general context of agricultural and environmental analysis. The flow-injection systems are valuable for sample introduction; appropriate dispersion control allows the analysis of solutions containing as much as 40% (w/v) urea or phosphate in fertilizers. A study on the determination of cadmium in soil extracts by on-line ion-exchange preconcentration and flame a.a.s. detection is described. The interpolative standard-addition method with i.c.p./a.e.s. detection is outlined. Improvements in the determinations of selenium in environmental samples by hydride-generation a.a.s. and of mercury by cold-vapour a.a.s. are reported.     

Measurement of uranium isotope ratios in solid samples using laser ablation and diode laser-excited atomic fluorescence spectrometry

A diode laser is used for the selective excitation of ²³⁵U and ²³⁸U in a laser-induced plasma applying Nd:YAG laser pulses to UO₂ samples. The diode laser is rapidly scanned immediately following each laser sampling and the resonance atomic fluorescence spectrum for both isotopes is obtained on a pulse-to-pulse basis. Time-integrated measurements, with the diode laser fixed at either isotope, were also made. Optimum signal-to-noise was obtained at a distance of 0.8 cm from the sample surface, a pressure of 0.9 mbar and a Nd:YAG laser pulse energy of 0.5 mJ (880 MW cm⁻²). Three samples with 0.204, 0.407 and 0.714% ²³⁵U were measured. For example, for the UO₂ pellet with the natural uranium isotopic composition (99.281% ²³⁸U and 0.714% ²³⁵U), the accuracy and precision were 7% and 5% (460 shots), respectively, limited by the continuum emission background from the laser-induced plasma.     

Atmospheric pressure microwave induced plasma ionization source for molecular mass spectrometry

An atmospheric pressure microwave induced plasma ionization (AP-MIPI) source design for molecular analysis is presented. It consists of three sections: the torch, the microwave cavity, and the vacuum interface. The torch uses an oscillating capillary nebulizer for introduction of aqueous solutions into the afterglow of the MIP. Samples introduced into the afterglow of the plasma are ionized by protonated solvent molecules in a fashion similar to the chemical ionization process. The ions are then transported into the mass spectrometer using a heated capillary tube. The combination of an improved torch design and the heated capillary tube provides a stable ionization source for direct aqueous solution introduction with flow rates of up to 0.5 mL/min. The system works well with solvent compositions similar to those used in high performance liquid chromatography. For most samples studied, the protonated molecules were the base peaks of the mass spectra. A linear dynamic range of at least two orders of magnitude and an upper limit of quantitation of 5 ng were observed for alanine. The technique was shown to maintain reproducibility and moderate loss of sensitivity (33% reduction) when an amino acid solution containing a sodium phosphate buffer was analyzed. The optimization of experimental parameters with respect to the torch and vacuum interface is discussed.     

Calibration graphs for steels by IR laser ablation inductively coupled plasma atomic emission spectrometry

Infrared laser ablation (IRLA) was studied as a sample-introduction technique for the analysis of steels by inductively coupled plasma atomic emission spectrometry (ICP–AES). A comparison of two IRLA–ICP–AES systems based on Q-switched nanosecond Nd?:?YAG lasers was performed. The beam of the Lina-Spark atomizer (LSA Sarl, Cully, Switzerland) based on the Surelite I-20 laser (Continuum, USA) was moved along a circle. A Perkin–Elmer Optima 3000 DV ICP system was used both with lateral and axial viewing modes. A laboratory-made ablation system based on the Brilliant laser (Quantel) was coupled to a Jobin-Yvon 170 Ultrace ICP (lateral viewing, polychromator part employed). A sample was rotated along a circle during ablation. Linearity of calibration plots was verified at least up to 19% Cr and 12% Ni without internal standardization for both LA–ICP–AES systems. Other elements examined were Mo up to 3%, Mn up 1.5%, Si up to 1.7%, and Cu up to 0.15%. The reproducibility was in the range 5–1 %RSD for a mass percentage 0.5–20% of steel constituents. The relative uncertainty of the centroids of the calibration lines was in the range from ± 4% to ± 12% for Cr, Ni, Mn, Mo, and Si, and from ± 8% to ± 19% for Cu. The lowest determinable quantities were calculated for calibration dependencies. Performances of both the IR-LA–ICP–AES were comparable.     

Calibration graphs for steels by IR laser ablation inductively coupled plasma atomic emission spectrometry

Infrared laser ablation (IRLA) was studied as a sample-introduction technique for the analysis of steels by inductively coupled plasma atomic emission spectrometry (ICP-AES). A comparison of two IRLA-ICP-AES systems based on Q-switched nanosecond Nd: YAG lasers was performed. The beam of the LINA-Spark atomizer (LSA Sarl, Cully, Switzerland) based on the Surelite 1-20 laser (Continuum, USA) was moved along a circle. A Perkin-Elmer Optima 3000 DV ICP system was used both with lateral and axial viewing modes. A laboratory-made ablation system based on the Brilliant laser (Quantel) was coupled to a Jobin-Yvon 170 Ultrace ICP (lateral viewing, polychromator part employed). A sample was rotated along a circle during ablation. Linearity of calibration plots was verified at least up to 19% Cr and 12% Ni without internal standardization for both LA-ICP-AES systems. Other elements examined were Mo up to 3%, Mn up 1.5%, Si up to 1.7%, and Cu up to 0.15%. The reproducibility was in the range 5-1 %RSD for a mass percentage 0.5-20% of steel constituents. The relative uncertainty of the centroids of the calibration lines was in the range from +/- 4% to +/- 12% for Cr, Ni, Mn, Mo, and Si, and from +/- 8% to +/- 19% for Cu. The lowest determinable quantities were calculated for calibration dependencies. Performances of both the IR-LA-ICP-AES were comparable.     

A mobile mass spectrometry laboratory for isotopic ratio measurements of uranium and plutonium

A modified quadrupole mass spectrometer is housed in a van that serves as a mobile laboratory to provide on-site determinations of isotopic ratios and concentrations of uranium and plutonium. Each element can be determined at 1–3 ng levels with precisions of 1–2%.     

Investigation of multi-layered silicate ceramics using laser ablation optical emission spectrometry,laser ablation inductively coupled plasma mass spectrometry,and electron microprobe analysis

The applicability of laser ablation (LA) inductively coupled plasma (ICP) spectrometry for assessing elemental distributions in layered ceramics was investigated and compared with electron probe microanalysis (EPMA). Ordinary glazed wall tiles were employed as model specimens due to their defined structure and composition. They were used for calibration in the analysis of ancient pottery. A qualitative depth profile was acquired by single-spot laser drilling perpendicular to coatings with a Nd:YAG (1064 nm) laser coupled with an ICP optical emission spectrometer (OES). The lower lateral resolution associated with the laser spot diameter of 1.0 mm led to smoothing of the depth profile due to the averaging of local irregularities. In addition, transverse line scans by ablation across the tile section using an ArF* (193 nm) laser coupled with an ICP mass spectrometer (MS) were performed. LA-ICP-OES depth profiles and LA-ICP-MS transverse scans were validated by EPMA section scans and 2D back-scattered electrons images. The LA-ICP-OES acquisition was less dependent on sample surface and layer irregularities, whereas the transverse line scan over the tile section with the small-spot beam offered insight into the micromorphology of the individual layer. The combined approach revealed the occurrence of individual mineral grains, micro-heterogeneities and the character of interfaces between layers.     

Internal standardization with yttrium spectral lines using axial-viewing inductively coupled plasma atomic emission spectrometry for plant certified reference materials analysis

The performance of yttrium as internal standard was investigated when aspirating digested samples or alternatively slurries of certified plant reference materials. The stability of the yttrium signal used for analyte signal normalization was examined for three ionic emission lines of yttrium. The results showed that the use of yttrium was beneficial; however for the slurry sample introduction technique it was not equivalently efficient in terms of overall recovery. In this case, the employment of a cyclonic instead of a double-pass spray chamber in combination with yttrium internal standardization leads to quantitative recoveries of the analytes.     

Kalman滤波技术校正电感耦合等离子体原子发射光谱分析中严重重叠的谱线干扰

针对ICP-AES中严重重叠谱线干扰的校正, 研究了若干因素对Kalman滤波器性能的影响。减小扫描步长可以增强Kalman滤波法解析重叠谱线的能力。当重叠线轮廓基本相同且扫描窗口内干扰元素只有一条谱线时, Kalman滤波法能分辨的重叠线对的最小峰间距为扫描步长的2～3倍。扫描窗口内较多的干扰元素谱线和重叠线对轮廓的显著差异有利于Kalman滤波器正确识别分析信号和干扰信号, 可以利用这两个因素有效地分辨峰间距很小甚至完全重叠的谱线。     

An improved method for determination of uranium isotopic composition in urine by alpha spectrometry

A comparative study of source preparation techniques to determine uranium isotopic composition by alpha spectrometry, namely electrodeposition and chemical stripping with polymeric membranae containing trioctylphosphine oxide (TOPO), is presented. The mean yield obtained for electrodeposition and TOPO deposition were 85% and 74%, respectively. The mean activity ratio²³⁵U/²³⁸U were 0.044 and 0.042 and the ratio²³⁴U/²³⁸U were 0.994 and 1.009, using electrodeposition and TOPO deposition techniques, respectively. The method of uranium separation from urine using an ion-exchange resin Dowex 1×8, chloride form and citrate form, was also studied. The obtained global yields of these methods were 50% and 41%, respectively.     

Characterizing uranium oxide reference particles for isotopic abundances and uranium mass by single particle isotope dilution mass spectrometry

Uranium and plutonium particulate test materials are becoming increasingly important as the reliability of measurement results has to be demonstrated to regulatory bodies responsible for maintaining effective nuclear safeguards. In order to address this issue, the Institute for Reference Materials and Measurements (IRMM) in collaboration with the Institute for Transuranium Elements (ITU) has initiated a study to investigate the feasibility of preparing and characterizing a uranium particle reference material for nuclear safeguards, which is finally certified for isotopic abundances and for the uranium mass per particle. Such control particles are specifically required to evaluate responses of instruments based on mass spectrometric detection (e.g. SIMS, TIMS, LA-ICPMS) and to help ensuring the reliability and comparability of measurement results worldwide. In this paper, a methodology is described which allows quantifying the uranium mass in single micron particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS). This methodology is characterized by substantial improvements recently achieved at IRMM in terms of sensitivity and measurement accuracy in the field of uranium particle analysis by TIMS. The use of monodisperse uranium oxide particles prepared using an aerosol generation technique developed at ITU, which is capable of producing particles of well-characterized size and isotopic composition was exploited. The evidence of a straightforward correlation between the particle volume and the mass of uranium was demonstrated in this study. Experimental results have shown that the uranium mass per particle can be measured via the ID-TIMS method to a relative expanded uncertainty of about 10% (coverage factor k = 2). The availability of reliable and validated methods for the characterization of uranium particles is considered to be essential for the establishment of SI-traceable measurement results. It is therefore expected that the method developed in this study is valuable for the certification of particulate materials in which the isotopic composition and the content of uranium must be accurately known.     

Element selective detection of molecular species applying chromatographic techniques and diode laser atomic absorption spectrometry

Tunable diode laser atomic absorption spectroscopy (DLAAS) combined with separation techniques and atomization in plasmas and flames is presented as a powerful method for analysis of molecular species. The analytical figures of merit of the technique are demonstrated by the measurement of Cr(VI) and Mn compounds, as well as molecular species including halogen atoms, hydrogen, carbon and sulfur.