Trace Impurities Research Articles

Universal Research Cryogenic Unit for Xenon Production

Xenon is a cryogenic product that is currently in short supply. Requirements for its purity are increasing. Its consumption in microelectronics, medicine, and space technology and for high-energy particle physics research is rising. The permissible impurity contents in Xe for various applications were analyzed. A universal research cryogenic unit for Xe production of throughput up to 10 Nm3/h of feedstock mixture was designed. A scheme with separation by rectification and preliminary catalytic and adsorptive purification of the feedstock was chosen. The unit was built in blocks so that processing schemes for Xe production from various mixtures, e.g., Kr–Xe, Xe–N2, Xe–O2, could be studied. Trace impurities in Xe were analyzed by gas chromatographs with thermal conductivity (TCD), He-ionization (HID), and flame-ionization detectors (FID). Water vapor in the analyzed gases was measured using laseroptical and coulometric hygrometers. The first runs showed that the unit could produce Xe of purity up to 99.9999 %. Experimental data for rectification of Xe to a purity of 99.999 % are presented. Xe could be purified experimentally from traces of CF4, C2F6, SF6, hydrocarbons, CO2, and H2 to 0.05; O2 and N2, 0.1; Kr, 0.01; and water vapor, 0.2 ppm.

High Temperature Oxidation Behavior of Nickel and Iron Based Superalloys in Helium Containing Trace Impurities

A high-temperature gas-cooled reactor (HTGR) is recognized as the best candidate reactor for next generation nuclear reactors. Helium is used to be the coolant in the core of the HTGR with temperature expected to exceed 900 °C at the core outlet. Several iron- and nickel-based superalloys, including Alloy 800H, Hastelloy X, and Alloy 617, are potential structural materials for intermediate heat exchanger (IHX) in an HTGR. Oxidation behaviors of three selected alloys (Hastelloy X, Alloy 800H, and Alloy 617) were investigated at four different temperatures from 650℃ to 950 ℃ under helium environments with various concentrations of O2 and H2O. Preliminary results showed that chromium oxide as the primary protective layer was observed on surfaces of the three tested alloys. Based on results of mass gain and SEM analyses, Hastelloy X alloy exhibited the best corrosion resistance in all corrosion tests. Further details on the oxidation mechanism of these alloys are presented in this study.

Data trend shifts induced by method of concentration for trace metals in seawater: Automated online preconcentration vs. borohydride reductive coprecipitation of nearshore seawater samples for analysis of Ni, Cu, Zn, Cd, and Pb via ICP‐MS

AbstractThis research compares performance, reproducibility, and detection limits of ambient seawater analysis for trace metals using both borohydride reductive coprecipitation and an automated chelation column (seaFAST™ 2) preconcentration for matrix interferent elimination on total and dissolved grab samples in nearshore to marine waters, over a broad concentration range, prior to inductively coupled plasma mass spectrometry (ICP‐MS) injection. A move to an online preconcentration method both minimizes sample preparation, and eliminates correction errors when accounting for trace impurities in precipitated samples, induced via reagents. The reproducability of the online preconcentration method described, coupled with low blanks and method detection limits (MDLs), demonstrates the effectiveness of the automated procedure using ethylenediaminetriacetic and iminodiacetate acid chelation exchange resin and multianalyte determination by ICP‐MS for total and dissolved Ni, Cu, Zn, Cd, and Pb in marine water samples. Average CASS‐5 recoveries using the online preconcentration method (n = 9) were 109% ± 7%, 104% ± 5%, 103% ± 7%, 101% ± 3%, and 86% ± 8%, respectively. The MDLs obtained from the automated method for Ni, Cu, Zn, Cd, and Pb were 3.3, 1.8, 13.5, 4, and 10 times lower, respectively, than for the Borohydride method. There were statistically significant differences between the methods for CASS‐5 recoveries of Ni, Cu, Zn (p < 0.0001), and Pb (p = 0.0024). Comparison of methods gave high concordance (rC ≥ 0.90) between methods for total and dissolved Ni, Cu, Zn, and Pb, and total Cd.

Analysis of radioactive waste generated during the cyclotron production of 99mTc

Past and prospective shortages of medical radioisotopes have driven recent developments in the direct production of 99mTc via the 100Mo(p,2n)99mTc reaction. The cyclotron-based production method has been shown to successfully produce 99mTc, however trace impurities present in the enriched molybdenum target can also lead to the unintended creation of other radioisotopes which constitute waste. The isotopic composition of the waste has to be investigated in order to determine how it can be handled, transported and safely stored. In this article, we report which waste radioisotopes are created alongside 99mTc during target irradiation. Results are based on the gamma spectroscopy of waste produced. Significant complexities in the emission spectra made automated identification of radioisotopes inaccurate; complexities were resolved using a manual radioisotope identification procedure. The impact of target composition, integrated beam current and duration of target irradiation on the waste produced was studied. Results indicate that an average of 0.059 ± 0.003 GBq of waste is generated per 1 GBq of 99mTc produced. Two-thirds of the total waste activity produced was attributed to 99Mo (T1/2 = 66 h) alone, while a total of fifty radioisotopes were found in the waste. Long-lived isotopes (T1/2 > 2 months) constituted only 1% of the total waste activity at end of beam (EOB). In conclusion, it was determined that the waste generated during cyclotron-based 99mTc production was acceptably low for routine clinical production.

The exchange bias effect in CoFe2O4/NiO nanocomposites prepared by chemical co-precipitation method

In this work, we report the synthesis of CoFe2O4/NiO nanocomposite systems via soft chemical co-precipitation method. Four samples (RM-1, RM-2, RM-3 and RM-4) were prepared with different weight percentage of NiO varying from 10% to 40%. Room temperature x-ray diffraction patterns of all the samples showed the presence of cubic spinel phase of cobalt ferrite with NiO phase without trace of any kind impurities. The magnetization M-H loops were recorded under field cool regime at 5 K and room temperature for all samples. Enhanced coercivity and exchange bias were observed with decrease of NiO weight percentage in the systems. Magnetic measurements showed that nanocomposite system RM-1 has high coercivity HC = 13.12 kOe and exchange bias HEB = 555 Oe at 5 K. Small amount of exchange bias was found in all nano composite system due to presence of weak interfacial spins coupling at room temperature.

Validated method for trace impurities analysis in bulk gas using Gas Chromatography with Pulse Discharge Helium Ionization Detection

Pulse discharge helium ionization detector (PDHID) is developed to respond the need of many applications in the area of chromatographic quantitative analysis. The PDHID is a general type of detector with very high detectability property covering a wide range of chemical compounds. Based on ISO/IEC 17025, a reliable and accurate of measurement result can be obtained by applying a validated method. This paper reports a validation study with regard to the application of GC-PDHID for trace impurity analysis in bulk gases. An optimized operating condition of GC was used to evaluate the method performance with parameters including precision (repeatability and reproducibility), linearity, limit of detection (LoD), and limit of quantification (LoQ). In this study, six trace compounds (CO2, H2, Ar, O2, CH4, and CO) in bulk gas were analyzed. The results show that the validated of the GC-PDHID method was repeatable and reproducible for the analysis of trace impurities in bulk gas. The %RSD of repeatability and reproducibility were found to be < 3.00% and < 10.50%, respectively. Good linearity of the validated method was obtained with the correlation coefficient (R2) higher than 0.99 for all six trace compounds. In addition, the calculated LOD and LOQ of the GC-PDHID were found to be < 0.60 and < 2.00 μmol mol−1 respectively. In conclusion, validated method of the GC-PDHID for the measurement of the six trace compounds in bulk gas is reliable and fit for its purpose, implying that the validated method can be used in daily measurement in the testing laboratory.

GC with FI and PDHI detection for trace impurity analysis in bulk gases: a comparative evaluation

Some experimental problems challenge the users when using a GC equipped with FID or PDHID detector in the context of trace level impurity analysis in ultra high purity bulk gases. In this study, a comparative evaluation of GC-FID and GC-PDHID is conducted based on both author’s experiment and literature review in terms of two technical aspects i.e., imitation and capability. Findings shows that both GC-FID and GC-PDHID reflect capability aspect through a pretty detection sensitivity and quantification at trace level of the impurity compounds. Regarding detectability range of compounds, the GC-FID has relatively lower than the GC-FID since the FID responds to only hydrocarbon-type impurity compound, while PDHID can detect almost any compound, except neon. In case of limitation aspect for these two instruments, detectable range of target compounds and operating cost are remarkable. In addition, in context of operating cost and maintenance, however, the FID is relatively inexpensive in comparison to that of PDHID. Besides aforementioned technical aspects, other capabilities and limitations of both FID and PDHID are also evaluated and compared.

Trace impurities measurement in ultra-high purity gases and their uncertainties: case study on permanent gas impurities in pure nitrogen

Trace measurement for gas impurities plays an important role in the quality determination of pure-gases. High purity gases will certainly have a higher economic value than gases with lower purity, especially for the ultra-high purity gases used in the preparation of standard gas mixtures. These types of gases shall have a maximum limit for their impurities, which should be verified by a validated method. In this study, an experiment was conducted to determine the impurities in three cylinders of ultra-high purity nitrogen (UHP N2) gases using a validated gas chromatography equipped with pulse dicharge helium ionization detector (GC-PDHID) method. The impurities detected by the GC-PDHID in the aforementioned UHP N2 samples consist of argon (Ar), oxygen (O2), methane (CH4), and carbon monoxide (CO). Meanwhile, hydrogen (H2) and carbon dioxide (CO2) cannot be seen on the chromatogram, then assumed to be lower than the PDHID’s detection limit. Concentrations of the impurities, along with their uncertainties, were found to be 0.987 ± 0.104; 5.818 ± 0.807; 3.163 ± 0.449; and 1.289 ± 0.158 μmol/mol for Ar, O2, CH4, and CO, respectively for the first N2 cylinder. H2and CO2 were estimated to be half of the limit of detection, and H2O component was quoted from the UHP N2 manufacturer’s certificate of analysis. The other two N2 cylinders showed almost similar amounts of impurities. Based on the results, the actual purity for each of the three N2 gases can be estimated as 99.9987% mol/mol; 99.9987% mol/mol; and 99.9988% mol/mol. It is expected that the results of this study could useful as reference for both pure-gas manufacturers and consumers to properly determine the quality of their products.

Impact of H2S in Predicting the Storage Efficiency of CO2 Injection in a High Pressure High Temperature (HPHT) Carbonate Aquifer - A Case Study in a Sarawak Offshore High CO2 Gas Field, Malaysia

Carbon capture and storage (CCS) has been identified as transformative technologies to achieve maximum reductions in CO2 emissions specified under the Kyoto Protocol. Historically, CO2 was first stored in reservoir indirectly back in 1970s during Enhanced Oil Recovery (EOR) process. Subsequently in 1996, the Sleipner CO2 storage project was officially implemented in Norway providing reference to future CO2 storage projects. As one of the main players in the oil and gas industries, PETRONAS has been proactive in finding an end-to-end technology development for CCS. The S field, a non-associated gas field, located 250km Offshore Sarawak Malaysia has recently been identified as a potential pilot for hydrocarbon production and CO2 storage as well as for surface and subsurface technologies maturation. The S field, a carbonate builds up platform is considered heterogeneous type of reservoir with porosity ranging from 15% to 40% and permeability ranging from 10md to 1300md. The S field contains 70mol% CO2 gas contents/30mol% hydrocarbons with some amount of impurities, N2, H2S and Hg. As a baseline development strategy to support this technology project, pure CO2 injection was considered, taking into account the separation technology efficiency to separate CO2 from other contaminants back into the same reservoir aquifer. However, due to some limitation on the surface technologies and economy limits, traces of impurities might be present in the system. There is a possibility of CO2 being co-injected with impurities, for instance H2S. The effect of the contaminant in the injected CO2 stream needs to be accessed to ensure the success of the CCS operation. Changes in base CO2 solubility may ultimately affect storage integrity and capacity. Since abundant solubility data of CO2 in water or brine are available in the literature and less data for this ternary system indicates that the understanding in quantifying the impact of this H2S impurity on CO2 solubility is essential. In this communication, extensive laboratory experiments on vapour-liquid equilibrium on the binary CO2-H2O (for experimental method validation) and ternary systems, CO2-H2S-H2O and CO2-H2S-Brine (0.35M) have been conducted at 423.15K, under pressure range of 1-35 MPa. The experimental method used in this work is the static-analytic type, taking advantage of two magnetic capillary samplers (Rolsi®, Armine’s Patent) developed in the CTP laboratory. This method allows the sampling of the mixture in both vapour and liquid phases and their analysis by Gas Chromatograph (GC). Thermodynamic modelling using the simplified Cubic Plus Association (sCPA) equation of state was able to satisfactorily describe the phase behaviour of the ternary systems. The impact of this H2S on CO2 injection for CCS has been further evaluated using numerical reservoir simulation. Existing reservoir dynamic modelling has been improved by incorporating the new experimental data. Simulations results were analysed based on the volume of CO2 dissolved in water and the total volume of CO2 gas injected. It shows that the introduction of H2S in injected CO2 promote a reduction of CO2 dissolved in water by 15%, however it eventually offers a similar amount of CO2 storage over long period of time.

Qualitative identification of impurities and principal component quantitative analysis of zearalanone on purity certified reference material

A liquid chromatography method was established for the determination of zearalanone (ZAN) raw material. The qualitative analysis of ZAN and its trace impurities was performed by ultra performance liquid chromatography-diode array detector (UPLC-DAD) and ultra performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS), and the response factors of each impurity were calculated. The three main organic impurities in the ZAN raw material were identified as β -zearalanol, α -zearalanol and a dehydration product of zearalanol with relative response factors of 0.5352, 0.8594 and 0.6973, respectively. The main component of the ZAN raw material was determined by the calibration factor normalization method. The purity of zearalanone was determined to be 99.6% with a standard deviation of 0.01%. This method can provide a technical support for the development of ZAN standard materials.

Origins of optical defects in rapidly grown DKDP crystals

Origins of the optical perturbations observed in slabs cut from rapidly grown DKDP crystals were identified. One is related to a post growth aging specific to DKDP and the other is a growth related segregation of traces of impurity. In addition, we propose a model which allows estimating the contribution of both origins to the observed optical heterogeneities.

A Review of Lanthanum Nanoparticles Impregnated Compound Arsenic Fixation Behaviour in Copper Aqueous Solution

Mining is a strategic sector of the global economy. However, the effects of mining and mineral processing activities on human health and environment cannot be overemphasized. The prevailing areas of concern include: air quality, water quality, water quantity and the ecological impacts of these activities. Mines activities bring about the release of used water into the environment, nearby rivers or into the ground. Streams, wells and lakes surrounding the mines and the underground water are affected by these mining and mineral processing activities. Arsenic is a major trace impurity that contaminates the air and water surrounding copper mines as a result of the various activities of mining and mineral processing. It therefore poses a worrisome threat to human health and sustainability of the environment. The use of lanthanum nanoparticles impregnated compound has been identified as an effective adsorption technique for the immobilization of arsenic from numerous aqueous solutions. The leaching behaviour of copper and arsenic were analyzed in this review to provide a knowledge on the behaviour of different adsorbents such as lanthanum nanoparticles impregnated compounds during the adsorption reactions. Lanthanum compounds have been applied in the arsenic fixation of different aqueous solutions in previous studies. Lanthanum nanoparticles impregnated compound changes the valence state of arsenic in aqueous solution and the establishment of the ability of the lanthanum nanoparticles impregnated compound to change the valence state of arsenic in aqueous solution suggest the possibility of successfully applying it in the arsenic fixation of hydrometallurgical processing of copper oxide and copper carbonate ores.

Optimizing luminescence sensitivity and moisture stability of porous coordination frameworks by varying ligand side groups

Hydrophobic ethyl, butyl or hexyl groups were introduced into the dicarboxylate ligand in the fluorescent porous coordination framework [Zn2(fda)2(bpy)] (LMOF-202, H2fda=9 H -fluorene-2,7-dicarboxylic acid, bpy=4,4′-bipyridine) for improving water stability and tuning oxygen sensitivity. The long hexyl groups gave satisfactory water stability but its oxygen sensitivity is low (70.8% fluorescence quenched at 1 bar O2 (1 bar = 105 Pa)). In contrast, the shorter side groups gave high oxygen sensitivity (93.9% fluorescence quenched at 1 bar O2) and low water stability. The derivation of the Stern-Volmer curves of the O2 luminescence quenching data from the linear form can be used for detecting trace impurities in the luminescent framework, being much more sensitive than conventional methods such as powder X-ray diffraction. Mixing the ethyl and hexyl groups in the solid-solution manner brought high oxygen sensitivity (96.4% fluorescence quenched at 1 bar O2) and high water stability simultaneously in the same coordination framework.

Three-dimensional modelling of edge multi-component plasma taking into account realistic wall geometry

A 3D multispecies fluid model has been implemented in the SOLEDGE-TOKAM suite of codes to address Scrape-off layer turbulent impurity transport. Zhdanov closure is used to address multi-component plasma modeling without any mass ordering or trace impurity assumption. Thanks to immersed boundary conditions, up to the wall simulations with non-axisymmetric plasma facing components are performed, in particular in the WEST configuration. A first proof of principle of interchange turbulence simulation of a Deuterium+Carbon plasma is also reported.

The Role of Ultrafine Crystalline Behavior and Trace Impurities in Copper on Intermetallic Void Formation

In the microelectronic component industry, because of the miniaturization of functional units, the interaction of materials and interfaces play a much more significant role in their performance. The result of this is that ultrafine crystalline and trace impurity behavior impact a device's operation to a much greater extent. This is the case with micro-connects for 3D integration, such as micro-bumps. Any unwanted crystalline behavior or interfacial segregated impurities can drastically alter a micro-connect's performance, with a particular issue being intermetallic void formation, often known as Kirkendall voiding. Currently, it is unclear under what conditions voids form and how to prevent them. This work studies the microstructural and compositional differences between samples with different voiding densities. Results show that samples that exhibit an ultrafine crystalline have a higher propensity to exhibit voiding. Also, there is a high concentration of trace impurities located in the electrochemically deposited Cu layer. After isothermal annealing, high concentrations of impurities are located at the interface between Cu and the Cu-Sn intermetallic compound of Cu3Sn. An alternative explanation to the traditional Kirkendall void formation theory is presented. The explanation is based on the interaction of trace impurities from the electroplating process and the microstructural evolution.

Enhanced Universal Quantification of Biomolecules Using Element MS and Generic Standards: Application to Intact Protein and Phosphoprotein Determination.

Tools that provide absolute quantification of biomolecules, particularly of proteins and their post-translational modifications, without needing suitable specific standards, are urgently demanded nowadays. To this end, we have significantly improved the recently introduced strategy based on CH4 addition to the plasma for absolute quantification of biomolecules using HPLC-ICP-MS. Addition of CO2 has been optimized and finally selected as a safer, more efficient quantitative strategy that is able to provide constant (<6% error) signal response factor for the six elements assayed (S, P, As, Se, Br, I) under compromised conditions. In the particular case of absolute protein quantification, accuracy and precision attainable for S-based absolute determination of intact proteins using internal and external S-generic standards were compared. Potential for real sample analysis was demonstrated by the high-sensitivity analysis of toxins present in snake venoms. Finally, multielemental speciation capabilities of the approach have been also demonstrated through P and S simultaneous analysis in phosphoproteomics. Simultaneous accurate determination of both absolute protein amount and corresponding phosphorylation degree for intact β-casein, and even impurity traces of κ and α-s1 isoforms present, has been successfully achieved using a simple mixture of inorganic P and S standards. The lowest detection limits (<1 fmol protein) ever published for S- and P-based intact protein quantification with ICP-MS are reported.

Crystal structure and magnetic properties of the ternary rare earth metal-rich transition metallides RE 14 T 3Al3 (RE = Y, Gd–Tm, Lu; T = Co, Ni)

Abstract The rare earth metal-rich RE 14 T 3Al3 series (RE=Y, Gd–Tm, Lu; T=Co, Ni) have been prepared by arc-melting the rare earth metals with appropriate amounts of TAl precursors. All compounds crystallize in the tetragonal crystal system with space group P42/nmc in the Gd14Co3In2.7-type structure. Two structures (Y14Co2.78(1)Al3.22(1): a=952.99(4), c=2292.98(10) pm, wR2=0.0423, 2225 F 2 values, 63 variables; Y14Ni3.07(2)Al2.93(2): a=955.06(5), c=2298.77(10) pm, wR2=0.0416, 2225 F 2 values, 63 variables) have been refined from single-crystal data, indicating T/Al mixing on one crystallographic site. The lattice parameters of all members have been refined from powder X-ray diffraction experiments. The Y and Lu containing compounds for T=Co and Ni exhibit Pauli paramagnetic behavior, indicating that the Co and Ni atoms exhibit no localized magnetic moment in line with a filled 3d band. The other compounds show paramagnetism, in line with the rare earth atoms in the trivalent oxidation state. Detailed magnetic investigations, however, were impossible due to the presence of e.g. RE 3 T trace impurities.

3D global impurity transport modeling with WallDYN and EMC3-Eirene

The global impurity migration code WallDYN was coupled to the 3D scrape off layer plasma solver EMC3-Eirene in order to make WallDYN applicable to 3D, non-toroidally symmetric, geometries. To make EMC3-Eirene suitable for migration studies its impurity transport module was extended to not just compute the impurity density in the plasma but also their deposition on the wall tiles. Originally EMC3 treats the impurity transport in the plasma as a diffusion convection problem thereby assuming immediate equilibration with the local background plasma in order to derive the local parallel convection velocity. While this is a reasonable approximation for light elements, it is not suitable for the treatment of heavy element which need significant time to equilibrate their velocity and temperature with the background plasma. Therefore EMC3-Eirene was augmented by a new kinetic impurity transport module that handles acceleration and thermalisation in a manner similar to what is implemented in the 2D trace impurity transport code DIVIMP. This paper will first describe the modification introduced in EMC3-Eirene and then show the differences between the impurity transport models and the new possibilities now available in WallDYN to interpret migration studies in non-toroidally symmetric geometries .

Synthesis of Goethite (α-FeOOH) Pigment by Precipitation Method from Iron Lathe Waste

&lt;p&gt;Lathe waste contains high iron content potential to be further processed into goethite pigment. The purpose of the research was to determine the effect of synthesis temperature on the structure, colour values, and morphology of goethite pigment. The synthesis was conducted with temperature variations of 60, 70, 80and 90°C. The XRD diffraction pattern shows that crystal structure of the product of all synthesis temperatures are goethite (α-Fe-OOH) with orthorhombic structure. The crystal size of the pigment ranges between 11.17 – 12.32 nm. Colour value analysis shows that product of 70°C synthesis temperature exhibits the highest lightness value about 40.5. Based on SEM-EDX imaging, the morphology of the samples is not uniform and forming agglomerates. Traces of impurities were detected, such as C and Na.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;p&gt;Keywords: Iron lathe waste, goethite, temperature, precipitation&lt;/p&gt;

Quantification of Trace and Ultra-trace Impurities in U-Zr Alloy by Inductively Couple Plasma Time of Flight Mass Spectrometry (ICP-TOF-MS) After Simultaneous Separation of U and Zr

Quantification of Trace and Ultra-trace Impurities in U-Zr Alloy by Inductively Couple Plasma Time of Flight Mass Spectrometry (ICP-TOF-MS) After Simultaneous Separation of U and Zr