Total Impurity Content Research Articles

Use of LC‐MS for the quality control of radiopharmaceuticals: example of [18F]ML10

[(18)F]ML10 is a promising novel low molecular weight positron emission tomography probe for apoptosis. As part of the quality control to support clinical studies for cancer therapy monitoring in the GSK Clinical Imaging Centre, a simple and sensitive liquid chromatography mass spectrometry method has been developed and validated for the quantification of total ML10 and impurity content in the final product. Chromatographic separation of ML10 and its radiolabelling precursor and impurities was achieved. Mass curves were constructed from a concentration range of ML10 and known impurities and were linear. Quantification was achieved by comparison of the area under the curve for ML10 content (m/z = 205) and the mass curve. The method was validated over a concentration range of 0.1-1 µg/ml.

Structural properties of boehmite produced by hydrothermal oxidation of aluminum

The structural properties of boehmite produced by hydrothermal oxidation of aluminum micron powder at 230–360°C and 3–20MPa in experimental flow reactor were studied depending on synthesis temperature. It was found that temperature increasing leads to less-ordered structure, particle agglomeration increasing, average crystal size increasing, specific surface decreasing, micropore volume decreasing and mesopore and macropore volumes increasing that corresponds with each other and correlates with the results of kinetic experiments. It was shown that reaction rate and conversion degree is given not only by temperature factor but also by product structural properties, which influence on the diffusion of water to the surface of reactive aluminum. It was shown an important role of flow reaction system in the providing of high rate of hydrothermal oxidation of aluminum and its conversion degree. The results of analysis of structural properties of boehmite confirmed in general that hydrothermal oxidation of aluminum is a promising method of the production of catalyst carriers and sorbents. It was established the possibility to assign the structural properties of nanocrystalline product by thermodynamic parameters within the experimental reactor. The results of mass spectrometric analysis showed that total impurity concentration in produced boehmite decreases in comparison with initial aluminum powder.

Crystal structure of the intermetallics produced by a calcium hydride method

Practically important intermetallics TiNi, NiAl, Ni3Al, TiAl, and Zr3Al2 (St 101 alloy for gas absorbers) produced by the calcium hydride method are comprehensively studied. The total content of impurities in these intermetallic powders does not exceed 1 wt %, and the fraction of the main phase in compounds with a narrow homogeneity region is at least 93–96 vol %. The main phases in all powders under study have a defectless crystal lattice, and their lattice parameters point to a low content of dissolved impurities in all intermetallics except for Zr3Al2. A high degree of homogeneity of the phase compositions of the intermetallic powders is supported by a scanning electron microscopy investigation.

Analysis of metal ion impurities in liquid crystals using high resolution inductively coupled plasma mass spectrometry

We have developed a method, using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS), to directly analyze metal ion impurities in liquid crystals (LCs). From measurements of resistivity, a commonly used technique for quality control of liquid crystal display (LCD) cells, we found that the resistivities of the LCs decreased significantly upon progressing through the different stages of the LCD cell manufacturing process. We determined the levels of metal ion impurities in the LCs through direct loading of diluted LC samples into the HR-ICP-MS system at a steady flow rate. Solutions featuring LC contents of 10% (v/v) were formed by dissolving each LC in isopropanol (IPA) containing acetone as a modifier. We quantified the trace metal ion impurities in the LC samples using a certified standard of metal ions diluted in IPA (external calibration) without the need for digestion pretreatment. Next, we compared the levels of metal ion impurities with the resistivities of the LCs at the different stages of the LCD cell manufacturing process. We confirmed that the resistivities of the LCs decreased as the total levels of metal ion impurities in the LCs increased. The total content of metal ion impurities added into the LC was higher in the siphoning process than in the one-drop filling process during the fabrication of LCD cells. The HR-ICP-MS method could, therefore, be used to directly measure metal ion impurities in LCs during the LCD cell manufacturing process, potentially replacing resistivity measurements of LCs as a means of quality control. We suggest setting 1400 ng L−1 as the limit of the total metal ion concentration in LCs used for LCD cell manufacturing. We used the HR-ICP-MS method to analyze a stained LCD panel to confirm that the content of metal ion impurities was indeed significantly greater in the stained area of the defected LCD. HR-ICP-MS appears to be a promising technique for the direct and effective analyses of metal ion impurities in LCs.

Atomic Layer Deposition of Amorphous Niobium Carbide-Based Thin Film Superconductors

Niobium carbide thin films were synthesized by atomic layer deposition (ALD) using trimethylaluminum (TMA), NbF5, and NbCl5 precursors. In situ quartz crystal microbalance (QCM) measurements performed at 200 and 290 °C revealed controlled, linear deposition with a high growth rate of 5.7 and 4.5 A/cycle, respectively. The chemical composition, growth rate, structure, and electronic properties of the films were studied over the deposition temperature range 125–350 °C. Varying amounts of impurities, including amorphous carbon (a-C), AlF3, NbFx, and NbClx, were found in all samples. A strong growth temperature dependence of film composition, growth rate, and room temperature DC resistivity was observed. Increasing film density, decreasing total impurity concentration, and decreasing resistivity were observed as a function of increasing deposition temperature for films grown with either NbF5 or NbCl5. Superconducting quantum interference device (SQUID) magnetometry measurements down to 1.2 K revealed a superc...

Formation of ultrafine SiO2 glass fibers by direct oxidation and combustion of Si particles in air flow

Ultrafine SiO2 glass fibers have been produced by direct oxidation and combustion of Si particles in air flow. Two kinds of fibers are observed, including submicron nodulated fibers and rod-like nanofibers. EDS analysis reveals that the chemical composition of the fibers agrees well with SiO2 and the total content of impurities is below 2.0%. It is proposed that the formation of the fibers is related to air flow and includes three steps, viz. spherical process and attachment of Si particles, oxidization, and smoothing of SiO2 chains. Due to the short reaction period and fast cooling rate, the SiO2 fibers have no time to crystallize and remain as glass.

Preparation of high pure zinc for electronic applications using selective evaporation under vacuum

m6N pure (99.9999%) zinc (Zn) was obtained through multiple vacuum distillations using 99.9% (m3N) pure Zn as input material at 2 kg batch-size. The soaking (distillation) temperature and the time of distillation at a dynamic vacuum level of 2.1 * 10 −3 Torr were optimized to achieve the desired purity, distillation rate and yield. The detailed analysis of input as well as purified Zn was carried out by inductively coupled optical emission spectroscopy (ICP-OES) technique for 14 major impurity elements. This confirmed the reduction of total impurity content from ∼983 to <1.53 μg/g (∼m6N) upon three consecutive distillations. The major impurities separated from the distilled zinc were Al, Cu, Fe, Sn, Pb, Si, Ca, As, Ag, Sb, Ni, Bi, Mg, Mn, etc. The trace oxygen as determined by O–N analyzer reduced from (230–350) μg/g for raw Zn to (20–27) μg/g for distilled Zn and the nitrogen impurity from (34–45) to (15–19) μg/g. Carbon determined by GD-OES reduced from (60–70) to (5–8) μg/g on purification. The overall yield of distillation was found to be 67.5%. Analysis results, i.e. yield and purity are discussed with respect to vapor pressure of impurities and mean free path. ( λ) of Zn vapor. Crystalline structure of distilled Zn was studied by XRD.

High-purity TeO 2–WO 3–(La 2O 3, Bi 2O 3) glasses for fiber-optics

TeO 2–WO 3, TeO 2–WO 3–La 2O 3 and TeO 2–WO 3–La 2O 3–Bi 2O 3 glasses were produced by high-purity oxides mixtures melting in crucibles of gold or platinum in purified oxygen atmosphere. The total content of Cu, Mn, Fe, Co and Ni impurities was not more than 0.1–2 ppm wt in glasses and below 0.1 ppm wt in the initial oxides. The hydroxyl groups absorption coefficients of the tellurite glasses at the maximum of the absorption band ( λ ∼ 3 μm) lay in the region of 0.01–0.001 cm −1. Stability to crystallization characterized by T x − T g = 150–190 °C was demonstrated for high purity 75TeO 2–25WO 3 glasses by DSC-measurements. There were no thermal effects of crystallization and crystallized phases fusion in case of La 2O 3-containing glasses. The optical absorption losses, measured by the laser calorimetry method at λ = 1.06, 1.56 and 1.97 μm, did not exceed 40–120 dB/km for glass samples. The multimode optical fibers with optical losses of 50–250 dB/km at 1.2–2.2 μm were produced from high-purity TeO 2–WO 3–(La 2O 3, Bi 2O 3) glasses.

Production and properties of high purity TeO 2− WO 3−(La 2O 3, Bi 2O 3) and TeO 2− ZnO−Na 2O−Bi 2O 3 glasses

TeO 2–WO 3 (TW), TeO 2–WO 3–La 2O 3 (TWL), TeO 2–WO 3–La 2O 3–Bi 2O 3 (TWLB) and TeO 2–ZnO–Na 2O–Bi 2O 3 (TZNB) glasses were produced by high-purity oxide mixtures melting in platinum or gold crucible at 800 °C in the atmosphere of purified oxygen. The total content of Cu, Mn, Fe, Co and Ni impurities was not more than 0.1–0.5 ppm wt in the initial oxides and glasses. The stability of TZNB glasses to crystallization, characterized by (T x − T g) value more than 150 °C, was demonstrated by DSC measurements at heating rate 10 K/min. In the case of La 2O 3-containing glasses the thermal effects of both crystallization and fusion of the crystallized phases were not observed. The hydroxyl groups absorption coefficients of pure tellurite glasses at the maximum of the absorption band (λ ~ 3 μm) were in the region of 0.012–0.001 cm −1. The optical absorption losses, measured by the laser calorimetry method at λ = 1.56 and 1.97 μm, did not exceed 100 dB/km.

Temperature‐concentration oscillations as a result of nanoheterophase structure of concentrated aqueous solutions of salts

AbstractDetailed precision investigation of aqueous solutions of NaBr·2H2O, KBr, RbNO3, and K2SO4 salts showed oscillations of crystal‐solution phase equilibria in the temperature range of 15–45 °C. The maximum deviations from the smooth correlation between the saturation temperature and the salt concentration (up to 4% of concentration and up to 10 °C) were found to correspond to simplest salt‐water ratios. Recently, similar trends were observed for NaNO3, KNO3 and K2CrO4 solutions. Oscillation amplitudes for saturation temperature in the investigated series decreased in the following orders: Na+→K+, Rb+, NH4+ (nitrate systems), CrO42–→SO42– and Br–→NO3– (potassium systems), and NO3–→Br– (sodium systems). Increase in total content of impurities (2‐4‐fold) in solution results in 1.5‐2‐fold elevation of the oscillation amplitudes. A concept of nanoheterophase solution was suggested to account for the observed temperature‐concentration oscillations. The concept is based on the original experimental data on interrelated variation of different properties of aqueous salt solutions depending on their concentrations. Characteristic features of the phase diagrams are discussed and influence of the oscillations on crystal growth is elucidated. (© 2010 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Improving the reliability of welded joints in bulk-quenched electrosteel rail

Metallurgical methods of improving the reliability of the weld seam in bulk-quenched electrosteel rail are considered: optimization of the chemical composition in terms of the basic elements and total impurity content; improvement in plastic properties of the rail by reducing the hardness; and removal of nonmetallic inclusions from the steel. Instability is seen in the weldability of the rails and also in the composition, with the same set of mechanical properties. The need for improvement in welding technology is shown; without the elimination of existing problems, the weldability of electrosteel rail cannot be guaranteed.

Substatiation of technological modes for effective operation of oxidative-sorption units of water treatment

The paper assessed the degree of oxidative-sorption purification of model waters on a local unit of drinking water conditioning, capacity up to 1 m3/h. It is shown that the quality of the effluent in terms of generalized indicators characterizing the total content of organic impurities, corresponds to regulatory requirements for drinking water. The replacement of ozonization with O3/UV treatment increases the fraction of absorbed ozone and the destruction degree of organic impurities. The degree of oxidative-sorption of water treatment by all parameters being controlled is higher than the adsorption one.

Iron Gettering in CZ Silicon during the Industrial Solar Cell Process

We investigated the impact of using low quality feedstock such as recycled silicon and simplified pulling condition on the performance of CZ silicon solar cells. Groups of wafers carefully chosen from different ingots were analyzed after different solar cell process steps by minority carrier lifetime measurements, by measurements of the interstitial iron content and by measurements of the total impurity content using NAA. Our results show that the main electronic properties of the ingots, namely the carrier lifetime, interstitial iron content and base resistivity are strongly affected by feedstock quality. Surprisingly, high solar cell efficiencies were achieved using highly contaminated silicon. These positive results are due to the beneficial effect of impurity segregation gettering by phosphorous diffusion and aluminum alloying. Post-diffusion gettering by an additional annealing step was demonstrated to enhance the charge carrier lifetime.

Compensation-driven superconductor-insulator transition

The superconductor-insulator transition in the presence of strong compensation of dopants was recently realized in La doped yttrium barium copper oxide. The compensation of acceptors by donors makes it possible to change independently the concentration of holes $n$ and the total concentration of charged impurities $N$. We propose a theory of the superconductor-insulator phase diagram in the $(N,n)$ plane. It exhibits interesting features in the case of strong coupling superconductivity, where Cooper pairs are compact nonoverlapping bosons. For compact Cooper pairs the transition occurs at a significantly higher density than in the case of spatially overlapping pairs. We establish the superconductor-insulator phase diagram by studying how the potential of randomly positioned charged impurities is screened by holes or by strongly bound Cooper pairs, both in isotropic and layered superconductors. In the resulting self-consistent potential the carriers are either delocalized or localized, which corresponds to the superconducting or insulating phase, respectively.

Numerical study and experimental investigation of zone refining in ultra-high purification of gallium and its use in the growth of GaAs epitaxial layers

A numerical study has been carried out to optimize the zone refining process parameters such as zone length, zone travel rate, number of passes and the effect of molten zone stirring in ultra-high purification of gallium. Theoretical interpretation of the impurity concentration profile along the refined gallium ingot is also ascertained. Based upon the optimized parameters obtained through the study, 5N2 (99.9992% pure) gallium is subjected to zone refining for 50 passes and mechanically stirred at 20–35 rpm by a rotational mechanism in the directional freezing system. The refined gallium has a purity level of 7N2 (99.999992%) and the total impurity concentration is reduced to 77.7 ppb with respect to 24 impurities, as analyzed by glow discharge mass spectrometry (GDMS). The purified gallium is used as the starting material to grow GaAs epitaxial layers by liquid phase epitaxy technique. The quality of the grown layer is tested by secondary ion mass spectroscopy (SIMS), Hall measurements and low-temperature photocapacitance techniques.

Optimization of gettering processes of metallurgical-grade silicon for solar cell applications

AbstractConversion efficiency of a solar energy in the electric is substantially determined not only by the total impurity concentration in solar cell element, but also by impurity chemical and physical state. Gettering processes, which are included in the technology of solar cell manufacturing, are usually used for such impurity redistribution. In order to optimize gettering processes we developed a program tool based on the fundamental physical and chemical laws. The description of physical and chemical behaviour of impurities in silicon is based both on known experimental data, and on calculations of necessary parameters by means of present-day thermodynamic and quantum-chemical methods. Developed tool helps to choose a gettering regime (a temperature profile, time, getter layer thickness) for optimization of these processes for the given initial chemical composition of the silicon wafer. Possibility of analysis of recombination activity of various types of defects in silicon on the basis of carrier lifetime criterion allows to obtain an estimation of efficiency of the gettering processes. Using this program tool we demonstrated that solar cell efficiency can be significantly increased by optimal choice of gettering conditions.

A study of Lux-Flood acid-base reactions in KBr melts at 800°C

The dissociation of CO32− (pK = 2.4 ± 0.2) and precipitation of MgO (pLMgO = 10.66 ± 0.1) in a KBr melt at 800°C were studied potentiometrically with the use of a Pt(O2)|ZrO2|(Y2O3) membrane oxygen electrode. The direct calibration of the electrochemical circuit allowed only the equilibrium concentration of O2− (of strong bases) to be determined in the melt. The total concentration of oxygen-containing impurities, including CO32− and CO42− weak bases, can be found by the potentiometric titration of a sample of KBr by adding MgCl2 (Mg2+), a strong Lux-Flood acid, which causes the decomposition of these oxygen-containing anions. This reaction can also be used to remove oxo anions from alkali metal halide melts.

An evaluation of the purity of volatile compounds on the elemental composition of impurities

By the example of chemical elements in the form of elementary substance it was shown that the total content of elemental impurities can be considered as an objective and generalized index of the purity of individual matter. Impurity composition of the volatile compounds evaluated on the experimental results was presented in the form of two information files: (i) the content of chemical elements for low-volatile impurities, and (ii) the content of impurities with specified molecular structure (taking into account that the volatility of impurity and base is comparable). A unified approach to the presentation of the impurity composition data of volatile compounds, which considers the elemental composition of both groups of impurities and allows estimating of the total content of elemental impurities in compound, has been developed. In the framework of this approach the average total impurity content of the high-purity volatile chloride samples, which are available at the Collection Exhibition of Special Purity Substances, were evaluated.

Stability of doripenem in vitro in representative infusion solutions and infusion bags

Background: Doripenem, a new parenteral carbapenem with broad-spectrum antibacterial activity, is indicated for the treatment of complicated intra-abdominal infections and complicated urinary tract infections, including pyelonephritis. According to the US prescribing information, the carbapenems imipenem and meropenem are stable in sodium chloride for 4 hours.Objective: The aim of this study was to assess the stability of doripenem following constitution (50 mg/mL) and in injection solutions in vitro (0.9% sodium chloride and 5% dextrose) at a concentration of 5 mg/mL in room and refrigerated conditions.Methods: The stability of doripenem was assessed (1) under room-temperature conditions (25°C ± 2°C, 60% ± 5% relative humidity, under fluorescent light) immediately after constitution in vials with sterile water; (2) under room conditions and refrigerated conditions (5°C ± 3°C, 60% relative humidity, protected from light) immediately after constitution with sodium chloride or dextrose in 3 different infusion bags (polyvinyl chloride [PVC], PVC with vial adapter, and polyethylene); and (3) under room and refrigerated conditions using 500-mg doripenem vials that had been stored for 12 months in room temperature and protected from light before constitution with water and dilution in sodium chloride or dextrose injection. Doripenem 5 mg/mL and related substances (degradation products and impurities related to doripenem) were measured using a validated high-performance liquid chromatography method. Doripenem was considered stable if its concentration remained within 90% to 110% of the initial concentration and the total concentration of degradation products and impurities related to doripenem was ≤5%. Appearance of the solutions was assessed using clarity and comparison to color standards; pH, using standard methodologies; and particulate matter, using light-obscuration and microscopy.Results: Three lots of doripenem were assessed. Doripenem potency in constituted suspension (50 mg/mL) remained unchanged (means, 99.2% and 99.3%, respectively, of initial doripenem amount) for up to 60 minutes in room or refrigerated conditions prior to transfer to infusion bags. The doripenem 5-mg/mL infusion solution retained its potency for 12 and 72 hours under room and refrigerated conditions, respectively, in 0.9% sodium chloride injection, and for 4 and 48 hours under room and refrigerated conditions, respectively, in 5% dextrose injection (mean percentages of initial doripenem concentration, 95.5% and 96.6% under room and refrigerated conditions, respectively). Comparable results were obtained with vials of doripenem that had been stored for 12 months at room temperature and protected from light and then constituted (50 mg/mL). Doripenem 5 mg/mL in 0.9% sodium chloride injection or 5% dextrose injection retained its potency in room conditions at the end of a 4-hour drip period when used with conventional infusion sets (mean, 96.6%) or Di(2-ethylhexyl)phthalate-free infusion sets (mean, 99.3%).Conclusions: Doripenem 5 mg/mL was stable for up to 12 hours in vitro in 0.9% sodium chloride at room temperature. Therefore, doripenem can be constituted, mixed with infusion fluids in the pharmacy, stored, delivered, and infused into a patient within a time frame suitable for 4-hour extended infusions.

Influence of Structure Changes in E110 Alloy Claddings on Ductility Loss Under LOCA Conditions

Abstract Microstructural changes are analyzed in specimens of E110 cladding tubes that have varying total impurity contents and differing residual ductility after interaction with steam at 1100 and 1200°C to 10–18 % ECR. It is shown that characteristics of the microstructure and the fracture behavior of tube specimens substantially depend on attendant impurities (C, Si, Ni, P, Cl, etc.). The total content of impurities available in the E110 alloy tubes varied from 35 to 140 ppm. With an increase in steam temperature from 1100 to 1200°C the influence of impurities on ductility of the tubes becomes weaker. The results of X-ray spectral examinations of niobium and oxygen distributions and microhardness measurements within the cladding wall after high temperature oxidation are presented. Methods of optical and electron microscopy were used to quantitatively analyze the interrelation between microstructural changes and fractures characteristics as a result of interaction with the high temperature steam environment. This work has suggested the likely reason for the losses of ductility in the studied specimens is the different contents of impurities that govern the types of microstructures formed as a result of the β →α transformation in the prior-β region of the specimens. The primary microstructural characteristics that govern the residual ductility of the E110 specimens is the morphology of the α phase platelets in the prior-β region (parallel plate or basket weave), and the quantity and brittleness of a second “dark” phase precipitate in the prior-β region.