Determination Of Trace Impurities Research Articles

Quantitative evaluation of low-concentration OH impurities in quartz glass by infrared photothermal deflection spectroscopy

.Impurity control in materials is of great importance to achieve excellent performance, yet the quantitative determination of trace impurities, especially OH, is extremely difficult using today’s characterization techniques. Here we report the determination of trace amounts of OH in quartz glass plates by photothermal deflection spectroscopy (PDS) extended to the IR region. PDS detects trace OH based on the amount of heat generated during non-radiative processes during light irradiation. IR absorption spectra of quartz glasses with five different OH concentrations were investigated. In addition to the standard OH band around 3640 cm−1, we find that there are combination modes, overtones, and water-induced IR features. The presence and OH concentration dependence of these species reveal the role of impurities in quartz glass. The PDS is effective in quantifying OH concentrations below 1 ppmw (parts per million weight) in quartz glass plates.

ICP-OES-Analysis for Humic Substance

The possibilities of optical emission spectrometry with inductively coupled plasma (OES-ICP analysis) (in radial plasma observation) of humic preparations (HP) are evaluated, the proposed technique allows quantifying up to 24 elements (As, Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, Si, S, Sr, Ti, V and Zn). The list of these elements will allow determining the value of such preparations for soil nutrition, and will also help to avoid danger if the content of toxic impurities in them goes beyond their maximum permissible concentrations. In the absence of standard samples with certified contents of the elements to be determined, the correctness of the analysis for the macrocomponent composition is confirmed by comparing the results of gravimetric determination of the ash content of the studied objects with the calculated data obtained when processing the results of OES-ICP analysis. Systematic errors in the determination of trace impurities were minimized by using the method of adding standard solutions (from matrix influences), as well as 6 parallel measurements of samples prepared independently of each other. The correctness of the methodology was also evaluated by using model solutions close to the possible micro-impurity mineral composition of HP using the Student’s t-test. The results obtained for the isolated fraction of humic acids are compared with the literature data.

Determination of critical trace impurities in “uranium silicide dispersed in aluminium” nuclear fuel by inductively coupled plasma mass spectrometry (ICP-MS)

Development of an indigeneous matrix separation system for the determination of trace impurities in U3Si2–Al dispersed nuclear fuel by inductively coupled plasma mass spectrometry.

Trace impurities analysis in UF4 via standard addition and 103Rh internal standardization techniques combined with ICP-MS

In order to determine trace impurities in the nuclear grade UF4, an analysis method based on the standard addition and 103Rh internal standardization techniques combined with ICP-MS has been established. The examination tests, including comparison with the quantity of trace impurities assigned in a certified reference uranium oxide and determination of the standard addition recovery, were performed to validate the accuracy and precision of the method. Total 42 trace impurity elements from Li to Bi were determined, with the method detection limit for the 42 impurities were found in the range of 0.0004–0.072 μg g−1. The recoveries were varied from 92% to 111%, and the relative deviations for most of the impurity elements were less than 10%. The method has been verified to meet the requirements of quality control for the UF4 and will be used in the molten salt reactor.

Matrix-assisted photochemical vapor generation for determination of trace bismuth in Fe[sbnd]Ni based alloy samples by inductively coupled plasma mass spectrometry

As the impurities in alloy may affect its mechanical and physical properties, the determination of trace elements is important to ensure the quality of alloy. However, accurate determination of trace impurities in alloy samples is a big challenge due to their complicated matrix and low concentrations. In this work, matrix-assisted photochemical vapor generation (PVG) was developed for the determination of impurity in alloy samples by inductively coupled plasma mass spectrometry (ICPMS). Bismuth was selected as the target element, which is detrimental to the strength of alloy even at very low concentration. The transition ions existed in alloy worked as the “sensitizers” for the efficient PVG of bismuth, and only formic acid and acetic acid were required for the analysis of alloy samples after digestion. This largely reduced the risks of sample contamination and analyte loss in multiple sample pretreatment involved in conventional analytical methods. The PVG efficiency of bismuth was greatly enhanced, making the sensitive and simple determination of trace analytes in alloy samples feasible. The limit of detection (LOD, 3σ) for Bi was found to be 0.4 ng L−1 corresponding to 0.54 ng g−1 for analysis of 0.5 g of alloy sample. A relative standard deviation (RSD) of 1.1% was obtained from seven replicate measurements of 0.5 μg L−1 Bi3+ in sample matrix. The proposed method was successfully applied for the determination of Bi in two certified reference materials (FeNi based alloys GBW01621 and GBW01622).

Gas Chromatography in Technology of High-Purity Noble Gases

The article presents the classification of the gas stream contaminant types in noble gas enrichment and purification units. For the safe and efficient system operation, it is necessary to choose the right method of multicomponent mixture separation and the optimal corresponding equipment operating parameters, also to offer a method to verify the absence of the undesirable contaminant in the gas stream. The methods to control the obtaining of required noble gas purity during cryogenic rectification are indicated. Application of various gas analysis methods is necessary to obtain high purity (up to 99.9999%) gases: gas chromatography, mass spectrometry, and their combination. The effect of the state of various components of a gas chromatograph on the analysis result are discussed. Recommendations are provided for noble gas analysis methodology, including the conditions for the determination of trace impurities. The article presents examples of practical application of gas chromatography to control the processes of noble gas enrichment and purification, using the example of production of pure xenon.

Determination of Trace Elements in High Purity Silver Granules Using Sector Field Inductively Coupled Plasma Mass Spectrometry

Abstract The trace impurities in high-purity silver granules were determined by fast scanning single collector sector field high-resolution inductively coupled plasma mass spectrometry (HR-ICPMS) after selective separation of the major matrix and silver as silver metal by hydroxylamine hydrochloride. In the filtrate, 32 major and minor metallic impurities including silver were determined using NIST SRM 1643e, Trace Elements in Water, VHG SM75 and SM90 (VHC Labs, Inc., Manchester, NH), and internal standards 7Li, 9Be, 45Sc, 72Ge, 115ln, 209Bi, and 238U. To minimize the matrix effect, reagent blank was measured and subtracted from the samples. The spectral interferences have been resolved by measuring the isotopes 55Mn, 56Fe, 75As, and 78Se in high-resolution mode (m/Δm = 10,000); 52Cr, 63Cu, and 64Zn in medium-resolution mode (m/Δm = 4,000); and others in low-resolution mode (m/Δm = 300). In the present study, the purity of the tested silver granules was found to be 99.9898 ± 0.00007 % with 95 % confidence level. The purity results obtained from impurity assessment by HR-ICPMS were compared with those of the results of the conventional gravimetric method and found to be comparable. Though the gravimetric process is a primary technique for purity determination and the results obtained are directly traceable to SI units, HR-ICPMS provides more information about the impurities present in the silver granules. The proposed method is convenient, accurate, and precise and can be used for purity as well as for determination of trace impurities in silver metal.

Fourier Transform Infrared and Raman and Hyperspectral Imaging Techniques for Quality Determinations of Powdery Foods: A Review.

Fourier transform infrared (FT-IR) and Raman and hyperspectral imaging (HSI) techniques have emerged as reliable analytical methods for effectively characterizing and quantifying quality attributes of different categories of powdery food products (such as milk powder, tea powder, cocoa powder, coffee powder, soybean flour, wheat flour, and chili powder). In addition to the ability for gaining rapid information about food chemical components (such as moisture, protein, and starch), and classifying food quality into different grades, such techniques have also been implemented to determine trace impurities in pure foods and other properties of particulate foods and ingredients with avoidance of extensive sample preparation. Developments of corresponding quality evaluation systems based on FT-IR, Raman, and HSI data that measure food quality parameters and ensure product authentication, would bring about technical and economic benefits to the food industry by enhancing consumer confidence in the quality of its products. Accordingly, a comprehensive review of the mushrooming spectroscopy-based FT-IR, Raman, and HSI literature is carried out in this article. The spectral data collected, the chemometric methods used, and the main findings of recent research studies on quality assessments of powdered materials are discussed and summarized. Providing a review in such a flourishing research field is relevant as a signpost for future study. The conclusion details the promise of how such noninvasive and powerful analytical techniques can be used for rapid and accurate determinations of powder quality attributes in both academical and industrial settings.

Ultra-low background mass spectrometry for rare-event searches

Inductively Coupled Plasma Mass Spectrometry (ICP-MS) allows for rapid, high-sensitivity determination of trace impurities, notably the primordial radioisotopes 238U and 232Th, in candidate materials for low-background rare-event search experiments. We describe the setup and characterisation of a dedicated low-background screening facility at University College London where we operate an Agilent 7900 ICP-MS. The impact of reagent and carrier gas purity is evaluated and we show that twice-distilled ROMIL-SpATM-grade nitric acid and zero-grade Ar gas delivers similar sensitivity to ROMIL-UpATM-grade acid and research-grade gas. A straightforward procedure for sample digestion and analysis of materials with U/Th concentrations down to 10 ppt g/g is presented. This includes the use of 233U and 230Th spikes to correct for signal loss from a range of sources and verification of 238U and 232Th recovery through digestion and analysis of a certified reference material with a complex sample matrix. Finally, we demonstrate assays and present results from two sample preparation and assay methods: a high-sensitivity measurement of ultra-pure Ti using open digestion techniques, and a closed vessel microwave digestion of a nickel–chromium-alloy using a multi-acid mixture.

Detection of trace impurities by time-of-flight mass spectrometry with laser-induced evaporation

A method for the determination of trace impurities of tens of ppm in solid materials is proposed, based on laser-induced evaporation of the substance in a vacuum in the forced congruence mode with simultaneous analysis of the evaporation products using a time-of-flight mass spectrometer. The results of measurements of the relative composition of impurities in α-corundum obtained from aluminum hydroxide (AlOOH) powder by high-temperature annealing (1500 and 1800°C) are presented. The necessity of comparative analysis is caused by a substantial difference in the measurement results for impurities in the initial material obtained by conventional methods. The reported values of the relative composition of impurities are in a good agreement with the results of inductively coupled plasma mass spectrometry.

Determination of trace impurities in U 3 0 8 by using the chromatograph of TBP-levextrel separation and ICP-OES

Determination of trace impurities in U 3 0 8 by using the chromatograph of TBP-levextrel separation and ICP-OES

Determination of trace impurities in advanced metallic nuclear fuels by inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS)

Development of a common analytical methodology for the determination of trace impurities in U–Ti, U–Zr and U–Mo alloy fuels by inductively coupled plasma mass spectrometry.

Spectrometric estimation of sample amount in aliquot for a direct solid sampling system and its application to the determination of trace impurities in silver nanoparticles by ETV-ICP-OES

A method based on a tungsten boat furnace vaporiser, tungsten sample cuvettes, and an inductively coupled plasma (ICP) optical emission spectrometer has been developed for the direct determination of silicon, phosphorus, and sulphur in silver nanoparticles. The important point in the proposed method is that the entire sample in each batch is vaporised, which enables simultaneous measurement of the emission of not only the analyte but also the silver matrix. Furthermore, since the silver nanoparticles are sufficiently pure, the contribution of impurities to the sample amounts will be negligible. Therefore, this estimation is suitable for measuring the sample amount in each aliquot instead of the conventional weighing procedure using a microbalance; therefore, no tedious weighing procedures for estimating the sample amount introduced into the ETV device are needed. An additional advantage is that pretreatment and/or predigestion are unnecessary. The sample throughput is approximately 35 batches per hour. The detection limits of silicon, phosphorus, and sulphur in the silver nanoparticles (dry powder) are 15, 4.2, and 62µgg−1, respectively. Analytical results for various silver nanoparticles as both dry particles and in suspended solutions are described, and these values are compared to those obtained by conventional weighing with a microbalance. This methodology is useful for rapid screening and accurate analysis of silver nanoparticles, especially for industrial applications.

Plutonium oxalate precipitation for trace elemental determination in plutonium materials

An analytical chemistry method has been developed that removes the plutonium (Pu) matrix from the dissolved Pu metal or oxide solution prior to the determination of trace impurities that are present in the metal or oxide. In this study, a Pu oxalate approach was employed to separate Pu from trace impurities. After Pu(III) was precipitated with oxalic acid and separated by centrifugation, trace elemental constituents in the supernatant were analyzed by inductively coupled plasma-optical emission spectroscopy with minimized spectral interferences from the sample matrix.

Direct determination of trace impurities in high-purity silicon nitride by axial viewed inductively coupled plasma optical emission spectrometry using a slurry nebulization technique

A simple, rapid and reliable method was developed for the determination of trace impurities in high-purity silicon nitride (nm- and μm-sized) by ICP-OES using a slurry nebulization technique.

ICP-OES: Why spectral lines are true peaks and how this can fool the user.

ICP-OES: Why spectral lines are true peaks and how this can fool the user.

Determination of Trace Impurities in Germanium Dioxide by ICP-OES, ICP-MS and ETAAS after Matrix Volatilization: A Long-run Performance of the Method

High-purity germanium compounds (e.g. germanium dioxide) are used these days in several applications (e.g. germanium-based detectors, semiconductors, fiber-optic systems). Thus, reliable methods for the routine determination of trace element impurities from germanium compounds must be developed. In this study, inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectrometry and/or electrothermal atomic-absorption spectrometry was used for the determination of fifteen impurity elements in germanium dioxide. Possible interference effects due to a germanium matrix were eliminated/minimized by a simple open-vessel volatilization of germanium tetra chloride before the determinations. The results, based on the data gathered over a period of one year, showed that the long-run performance of the method is good, and it can be used for routine analysis of impurity elements in high-purity germanium dioxide.

Оценка оптимальных параметров многоэлементных твердотельных детекторов для сцинтилляционного атомно-эмиссионного спектрального анализа

Introduction. In recent years, there has been an increased use of atomic emission spectral ( AES ) scintillation analysis with multi-element solid-state detectors ( SSD ) recording sequences of spectra for the rapid determination of trace impurities in powdered geological samples. The objectives of this study were to evaluate the optimal exposure time that provides the maximum signal-to-noise ratio ( SNR ) of the recorded spectral scintillations and, hence, the lowest detection limits of elements, and to estimate the effect of the SSD performance on this ratio. Derivation of the formula of the SNR. The time variation of the spectral line intensity is represented by a Gaussian function with the following parameters: the scintillation time and the number of photoelectrons generated by the scintillation. The SNR as a function of the scintillation intensity and time, spectral background intensity, exposure time, readout noise, and SSD area and dark current was determined for the two cases where the scintillation peak occurs at the beginning and middle of the exposure period. Analysis of the effect of the exposure time and SSD parameters on the SNR. The analysis was performed using three SSDs: BLPP-369M1 and BLPP-4000 photodiode arrays produced by VMK-Optoelektronika and a TCD1304DG charge-coupled device array produced by Toshiba. The experimentally obtained parameters of a 1 ms duration gold spectral line scintillation, during powder samples excitation on the spill injection method realizing equipment “Potok”, have been used in analysis. Results. It has been found that for achieving the maximum SNR for a 1 ms duration scintillation, the optimal exposure time is 0.8 ms for BLPP-4000, 1.1 ms for BLPP-369M1, and 1.2 ms for TCD1304DG. The expected reduction of the detection limits in the AES scintillation method compared to the conventional AES techniques is a factor of 30 for TCD1304DG, a factor of 50 for BSSA-369M1, and a factor of 110 for BSSA-4000. To obtain the AES method lowest detection limits, the intrinsic noise of the SSD (readout noise and dark current noise) should be less than the spectral background shot noise, the exposure time should be optimal, and the height of the photocell should be equal to the spectral line height. Keywords: time-resolved spectroscopy, atomic emission spectral analysis, scintillation, multi-element solid-state detectors, optimal exposure time. (Russian) DOI: http://dx.doi.org/10.15826/analitika.2014.18.1.004 S. A. Babin 1, 2 and Labusov 1, 2, 3 1 Institute of Automation and Electrometry, SB RAS, Novosibirsk, Russian Federation 2 VMK-Optoelektronika, Novosibirsk, Russian Federation 3 Novosibirsk State Technical University, Novosibirsk, Russian Federation

Trace amounts of impurities in electrolytic manganese metal by sector field inductively coupled plasma mass spectrometry

An analytical method, using sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) for rapid simultaneous determination of Be, Na, Mg, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, As, Sn, Sb, Pb and Bi in electrolytic manganese metal, was described. At the beginning, the samples were decomposed by HNO3 and H2SO4, and then analyzed by SF-ICP-MS. Most of the spectral interferences could be avoided by measuring in different mass resolution modes. The matrix effects due to the excess of sulfuric acid and Mn were evaluated. Correction of matrix effects was conducted by using the internal standard elements. The optimum condition for the determination was investigated and discussed. The detection limit is in the range of 0.001–0.169 μg/L. The current method is applied to the determination of trace impurities in electrolytic manganese metal. And experiments show that good results can be obtained much faster, more accurately and conveniently by current method.

A new method for on-line dissolution and determination of trace impurities in high silica material using inductively coupled plasma atomic emission spectrometry

A simple and rapid method has been developed for on-line dissolution of high silica material followed by the determination of trace impurities in ICP-AES. High silica material was placed in a mixture of HF and water (1 : 2) inside a polypropylene bottle. After capping the lid, the bottle was kept at room temperature (25 +/- 5) degrees C for 45 min with occasional manual shaking. The resultant solution in HF was tested for metallic trace impurities directly in ICP-AES. The test result of the rapid dissolution technique was checked with those obtained by conventional dissolution of the material in supra pure HF. The results obtained by two different sample dissolution techniques were in very good agreement. Accuracy of the method has been verified by analyzing certified reference high silica materials like quartz, SAB, SARM 49 and high purity silica, BCS-CRM.313/1.