Impurity Elements Research Articles

Itemized determination of As, Sb, Bi, Se, and Ge in graphite sample by HG-AFS with high-temperature microwave digestion.

In this paper, we optimized a method for fast and accurate determination of five impurity elements (As, Sb, Bi, Se, and Ge) in graphite samples to overcome the shortcomings of existing methods, such as complicated equipment, cumbersome process, multiple-time preparation, separate determination, and large error in results. Graphite samples were digested with HNO3-H2SO4-HClO4-HF in a high-temperature and high-pressure microwave digestion apparatus, and the elements were extracted and determined separately by AFS (atomic fluorescence spectrometry). There is no element loss during the processing and analysis of this method. The spike recoveries (As: 90.30%-102.3%, Sb: 90.73%-110.0%, Bi: 90.00%-99.67%, Se: 93.33%-110.0%, Ge: 92.26%-104.2%) and precision (RSD%; As: 1.34%-8.96%, Sb: 2.67%-7.10%, Bi: 1.83%-4.58%, Se: 0.36%-3.25%, Ge: 4.41%-8.65%) meet the requirements of the corresponding quality specifications. The method has some advantages (such as no elemental loss, fast testing, strong element targeting, and accurate results), and thus can achieve batch determination of graphite samples. The optimized method for graphite sample and final solution preparations can be used for diverse spectrometric technologies, and that for spectrometer conditions have reference value for HG-AFS instruments.

ВЛИЯНИЕ ПРИМЕСЕЙ НА ДЕГРАДАЦИЮ СОЕДИНЕНИЙ В СИСТЕМЕ Al – Au

Typical reasons for degradation of micro–welded bimetallic compounds of the aluminum-gold binary system are considered. These types of compounds are often used in the manufacture of semiconductor products (SCPs) and integrated circuits (ICs). Degradation of compounds, revealed during screen tests or during products operating, leads to failures, which dramatically reduces the reliability of electronic equipment (EE). The majority of degradation processes are based on diffusion phenomena, which are mainly determined by temperature, chemical composition and microstructure of metals and alloys. Impurity elements included in the gold coating have a significant effect on the degradation of the wire connections such as crystal contact pads – traverses of package terminals of SCPs. In this regard, it is worth analyzing the effect of various impurities on the diffusion processes and changes in the microstructure of the coating in order to find out the most dangerous chemical elements and determine their role in the degradation of compounds. The paper presents a review of references on the research subject. In the conclusion, the results of analysis in the field of the influence of impurity elements on the degradation of compounds in Al – Au system are summarized, conclusions are drawn about the key role of grain-boundary diffusion on the degradation of micro-welded bimetallic compounds.

Monitoring of Essential and Toxic Elements in Multivitamin/Mineral Effervescent Tablet Supplements and Safety Assessment.

Multivitamin/mineral (MVM) supplements are the most commonly utilized dietary supplements by many populations. However, there is a severe concern about their adverse effects due to elemental impurities. In the present study, it was aimed to determine the levels of 11 elemental impurities (Cd, Pb, As, Hg, Co, V, Ni, Se, Mo, Cu, and Cr) by inductively coupled plasma-mass spectrometry (ICP-MS) and evaluate the human health risk associated with the consumption of 33 MVM effervescent tablet supplements available in Turkey. The precision of the method in terms of relative standard deviation (RSD) was less than 4.6%. The accuracy of the method was tested with recovery experiments, and the results ranged between 86 and 107%. The impurity levels for Cd, Pb, As, Co, V, Ni, Se, Mo, Cu, and Cr were found between 0.011-0.050, 0.025-0.098, 0.018-0.056, 0.010-0.626, 0.027-0.290, 0.026-1.65, 1.92-21.83, 0.034-34.09, 0.140-183.9, and 0.033-13.10µg/g, respectively, and Hg was not detected in any sample. The calculated concentrations for elemental impurities complied with EMA and USP guidelines, except one supplement for Se (21.83µg/g) with a permitted limit of 15µg/g. The hazard quotient (HQ) and hazard index (HI) levels were below 1 for all samples within the ranges of 3.4 × 10-1-1.4 × 10-6 for HQ and 7.8 × 10-1-1.4 × 10-6 for HI indicating that there is no risk for consumption. The carcinogenic risk (CR) of As was between 1.7 × 10-6 and 5.9 × 10-6, below the threshold value of 1 × 10-4. The results showed that there is no risk to human health.

Trace element impurities in anode copper from Olympic Dam, South Australia

Anode copper is the intermediate product between copper smelting and electrorefining. Anodes are typically 98.5 to 99.8 % pure and require electrorefining to high-purity copper cathode that can be sold to customers. Impurity elements, including Ag, Au, As, Sb, Bi, Se, Te, Sn, Pb, Co, and Ni (alongside minor Fe, Al, and Si), are either dissolved within anode copper, or contained within micron-scale inclusions. To better understand the distribution of these impurities, a study of anode copper was undertaken on representative samples from the Olympic Dam anode plant, South Australia. Bulk assay for 61 elements of 269 sub-samples collected on a grid across a single anode, including the ‘ears’, shows homogeneity irrespective of location. The five most abundant impurity elements are As (mean 1279 ± 41 ppm), Se (218 ± 11 ppm), Sb (211 ± 8 ppm), Bi (202 ± 9 ppm), and Ni (195 ± 6 ppm). The assay data demonstrate that reliable, representative compositional data on the anode can be obtained from sampling and assay of only a limited part of the whole, including the ‘ears’.Trace element analysis of copper metal by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) allows quantification of dissolved minor components. Some metals, notably Ni, occur almost completely dissolved in copper. Other elements occur only partially in dissolved form, but the proportions measured in copper metal relative to bulk assay vary significantly from only ∼ 9 % for Pb, 13 % for Bi and Te, 25 % for Se, 29 % for Sn, 34 % for Sb, 55 % for As, and 60–70 % for Au, Ag, and Co. These results are consistent with the observation of a diverse suite of 1–10 µm-sized, rounded impurity inclusions containing Pb, Bi, As, Sb, Te, Se etc. that are associated with cuprite, Cu2O, and largely follow copper grain boundaries. The inclusions, each containing one or more crystalline (e.g., Cu-selenides, some Cu-Bi-arsenates, Sn-oxides and cuprite) and/or glassy phases (e.g., Cu-Pb-As-Sb-Bi-oxides), represents a trapped melt droplet, leading to the observed broad range of compositions.

Enhanced CMAS and hot corrosion degradation of YSZ thermal barrier coating with nano powders

Thermal barrier coatings are used to protect hot section parts of gas turbine engines. These coatings are subject to corrosion due to impurity elements in the fuel and dust absorbed from the atmosphere into the engine. The rough and porous surface nature of plasma-sprayed coatings facilitates the penetration of these factors into the coating. Coatings are damaged prematurely as a result of corrosion. In this study, nano-structure YSZ, YSZ + Al2O3, YSZ + TiO2, and YSZ + Al2O3 + TiO2 coatings were deposited on plasma sprayed YSZ coating by electrophoretic deposition method. Hot corrosion and CMAS resistance were investigated. The coatings were characterized by SEM, XRD, AFM, and microhardness before corrosion tests. The changes in the coatings after corrosion tests were characterized by SEM and XRD. The penetration behavior of corrosive factors was examined by elemental mapping with EDS. Nanostructure coatings deposited on APS YSZ made the surfaces of as-sprayed coatings more stable. The ability of these nanolayers to prevent pure penetration into coatings during hot corrosion and CMAS is limited. However, the Al2O3 + TiO2-doped nanostructure YSZ reduced the bond-layer oxidation. In addition, the addition of Al2O3 + TiO2 to the EPD deposited layer also reduced the tetragonal-monoclinic phase transformation that occurred in YSZ as a result of corrosion. Al2O3 and TiO2 additives alone are not effective in improving the corrosion behavior of coatings. Nanostructured coatings deposited with the EPD technique can help protect plasma-sprayed thermal barrier coatings against corrosion.

High-Performance N-Polar GaN/AlGaN Metal–Insulator–Semiconductor High-Electron-Mobility Transistors with Low Surface Roughness Enabled by Chemical–Mechanical-Polishing-Incorporated Layer Transfer Technology

High-Performance N-Polar GaN/AlGaN Metal–Insulator–Semiconductor High-Electron-Mobility Transistors with Low Surface Roughness Enabled by Chemical–Mechanical-Polishing-Incorporated Layer Transfer Technology

The comprehensive strategy in the human health risk assessment of total chromium impurities in cough syrups with Marshmallow Root (Althaea officinalis) available in Polish pharmacies: regulatory aspects and special emphasis on Cr(VI) mode of action

Chromium, which can currently only be considered pharmacologically active and not an essential element, is a very intriguing elemental impurity in final pharmaceutical products, especially traditional herbal medicinal products. This kind of traditional herbal medicinal product with Marshmallow root (Althaea officinalis L., radix) registered in the EU is widely used among the European population. The aim of this article is to propose a double regulatory strategy in assessing the human health risk of total chromium impurities in cough syrups with Marshmallow Root (Althaea officinalis) available in Polish pharmacies. We applied the strategy based on the requirements of the ICH Q3D (R1) guideline for the assessment of Cr impurities in final traditional herbal medicinal products with Marshmallow Root registered in the EU. Furthermore, we applied the strategy based on the concept of margin of exposure (MoE) considering Cr(VI) genotoxicity mode of action (MOA) and based on BMD10 for Cr(VI) as a point of departure (PoD). The total Cr content was in the range: 1.12–9.61 µg/L (in comparison with the ICH Q3D R1 guidelines: 1100 µg/g). Total Cr levels in a single dose were relatively high compared to raw results, but were not a threat to patients. Comparison of estimated results with oral PDE value for Cr in final drugs suggested by the ICH Q3D R1 guideline (10,700 µg/day) show that all the products analyzed were below this value (the highest result was 278.40 ng/day). Despite conservative assumptions, the MoE values obtained for Cr in daily dose for each Marshmallow Root cough syrup were above 10,000; therefore, exposure to Cr would not cause a health risk for specific population groups (children and adults). It can be summarized that each of the phytopharmaceuticals analysed with Marshmallow root available in Polish pharmacies does not represent a health hazard to patients. We confirm the safety of Cr impurities by applying a double regulatory strategy without the application of an expansive and demanding HPLC-ICP-MS technique for Cr speciation.

Features of rare earth elements geochemistry in coals of Central Kazakhstan

AbstractThis research presents the results of a comprehensive study of mineralogical and geochemical features of REE distribution in coals of Central Kazakhstan deposits—Karaganda coal basin and Shubarkol deposit, which have large hard coal reserves and are industrially important for the coal industry of Kazakhstan; the research is based on 205 samples of clayey interlayers and coal seams. It shows basic patterns of distribution and features of concentration for impurity elements, gives an estimate of the impurity elements concentration, including REE, defines conditions and factors of their accumulation, and studies features of their forms in coal and coal-bearing rocks, which allows estimating the mechanisms of their migration and conditions of accumulation. According to the results of geochemical indicators, the article establishes the factors of REE dislocation, reveals the composition of margin rocks that have influenced REE concentration in coal seams, and the presented latest data on mineralogy allowed to establish the ways of their transportation to the paleobasin during the syn- and epigenetic periods of formation of the coal deposits of Central Kazakhstan being researched. It was found that the coals are insignificantly enriched with heavy lanthanides from Ho to Lu. The distribution curves of UCC normalized REE values in the coals are similar and coincide, but they are less than the average value for world coal, and amount to only one-third of the UCC. It was found that the highest concentrations of all REE are characteristic of clayey interlayers and oxidized coals. The La/Yb ratio in this case increases upwards along the section, indicating mainly clastogenic mechanism of REE delivery to the coals. In coal and clay samples, the predominant mineral form of REE is light lanthanide phosphates. Identified particles of REE from minerals and their composition peculiarities suppose autigene nature of their formation. The formation of the bulk of autigene minerals occurred during the maturation of brown coals and their transformation into hard ones.

Phase-field simulation for evolution of iron-rich phase during solidification of Al–Si–Fe alloys

Iron is a common impurity element in Al–Si alloys. The existence of Fe promotes the formation of needle-like iron-rich phase, which has an adverse effect on the macroscopic mechanical properties. In this study, the effects of casting temperature, Fe content and melt ultrasonic treatment on the morphology of β-Al9Fe2Si2 were investigated by phase-field simulation and experiment. The results show that when the casting temperature is close to the liquidus temperature, the grain size of the precipitated phase will be refined. The increase of iron content in the alloy will promote the increase of average grain size and volume fraction of iron-rich phase by inhibiting the growth of α-Al grains. In addition, the elevation of both casting temperature and Fe content promotes the transformation of the β-Al9Fe2Si2 from short rod-like to needle-like with large scale. The melt ultrasound inhibits the transformation to β-Al9Fe2Si2 by promoting the nucleation and growth of α-Al8Fe2Si. Melt ultrasound, casting temperature and iron content together cause the change of needle-like iron-rich phase morphology.

Study on Removal Rule of Impurity Elements in Preparation of Ferromolybdenum from Calcium Molybdate

Study on Removal Rule of Impurity Elements in Preparation of Ferromolybdenum from Calcium Molybdate

Gamma-enhancement of reflected light images as a routine method for assessment of compositional heterogeneity in common low-reflectance Fe-bearing minerals

Abstract Incorporation of impurity elements into minerals impacts on their physical properties (e.g., reflectance, hardness, and electrical conductivity) but the quantitative relationships between these features and compositional variation remain inadequately constrained. Prior work has shown that gamma-enhancement of reflected light images represents a simple yet powerful tool to assess the compositional heterogeneity of single pyrite crystals as it can enhance subtle differences in reflectance between distinct domains with different minor element concentrations. This study extends the gamma correction method to several other common Fe-bearing minerals, magnetite, garnet, wolframite, and tetrahedrite-tennantite, which all have far lower reflectance than pyrite. Gamma-enhanced optical images reveal clear variations in reflectance that are either systematic with increased minor element concentration as the change in gray value on backscatter electron (BSE) images (in the case of magnetite, garnet, and tetrahedrite-tennantite) or contrasting (as in pyrite), yielding a convincing linkage between reflectance variation and compositional heterogeneity. Reflectance variation is an expression of the distribution of the average effective number of free electrons on the mineral surface that can re-emit light when excited by visible light. Gamma-enhanced images can reveal compositional heterogeneity in minerals such as wolframite where small atomic mass differences between substituting elements (Mn and Fe, in the case of wolframite) are virtually impossible to observe as a variation of gray values on BSE images. Results also demonstrate that Fe-rich domains in these minerals can be expected to have higher reflectance than Fe-poor domains whenever Fe is a major constituent. The greater reflectance is attributed to Fe ions having a greater effective number of free electrons than many other elements (e.g., Co, Ni, Si, Ca, Al, Mg, Mn, and As). The research highlights the utility of gamma correction as an inexpensive tool for routine evaluation of compositional heterogeneity in common Fe-bearing minerals, potentially obviating the necessity of a microbeam platform to correlate textures and composition.

Characteristics of the Discoloration Switching Phenomenon of 4H-SiC Single Crystals Grown by PVT Method Using ToF-SIMS and Micro-Raman Analysis.

The discoloration switching appearing in the initial and final growth stages of 4H-silicon carbide (4H-SiC) single crystals grown using the physical vapor transport (PVT) technique was investigated. This phenomenon was studied, investigating the correlation with linear-type micro-pipe defects on the surface of 4H-SiC single crystals. Based on the experimental results obtained using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and micro-Raman analysis, it was deduced that the orientation of the 4H-SiC c-axis causes an axial change that correlates with low levels of carbon. In addition, it was confirmed that the incorporation of additional elements and the concentrations of these doped impurity elements were the main causes of discoloration and changes in growth orientation. Overall, this work provides guidelines for evaluating the discoloration switching in 4H-SiC single crystals and contributes to a greater understanding of this phenomenon.

Assessment of the accuracy of the method of fundamental parameters for XRF analysis of soil samples using an ARL Quant’X energy dispersive spectrometer with the UniQuant software

X-ray fluorescent (XRF) analysis is one of the most widely used methods for analytical control of soil and rock samples, which allows determining a wide range of elements using a single sample with minimum costs. This work is aimed to expand the XRF capabilities in terms of obtaining calibration dependences for various types of samples. The work presents the results of the experimental assessment of the accuracy of the method of fundamental parameters for analysis of soil samples on a Quant’X energy dispersive spectrometer with the UniQuant software using artificial samples. The suggested methodical approach has shown the potentiality of using a Quant’X energy dispersive spectrometer with the UniQuant software for analysis of soil samples prepared by different methods (fused, pressed and bulk). The systematic deviation from the target value and a random error were estimated. For fused soil samples, deviations from the target value for most of the major components were (1.01) with a random error of 0.01 – 0.06. A Quant’X spectrometer with the UniQuant software allows determining light elements in fused samples with an error of up to 0.06. For the majority of impurity elements, a significant deviation was found, more than one (an underestimation of the determination results by an average of 1.18 times). This requires correction of the results obtained and the analysis error will be determined by values?? ranging from 0.01 to 0.1. In most cases, the deviation from the target value and the error of the element determination decreased as the sample preparation became more complex. After adjustment, bulk soil samples showed the highest error of the analysis results (from 0.1 to 0.2 for the major elements and 0.05 – 0.10 for impurity elements). The detection limits of some elements in fused soil samples were estimated. When the component content in the soil is more than 0.1%, the best option is to analyze fused samples. To determine concentration levels of about 50 ppm, it is proposed to measure pressed samples and take into account the increased error.

Development of a technique for X-ray fluorescence analysis of zinc-aluminum-magnesium alloys

A technique for X-ray fluorescence spectral analysis of zinc-aluminum- magnesium alloys has been developed, which allows the determination of Mg, Al, Pb, Si, Cu, Mn, Fe, Ni content in the alloy. The effect of the sample preparation method on the linearity of calibration graphs is revealed. The conditions for determining the main alloying (Al, Mg) and impurity (Pb, Fe, Cu, Si, Mn, Ni) elements by X-ray fluorescence spectrometry were studied. It is proposed to use the correction of the matrix effect by selecting alpha coefficients for the intensity of X- ray radiation with subsequent automatic conversion of the function into a linear form. Calibration graphs for determination of the elements in the corresponding ranges, i.e., Mg (0.00019 – 5.04%), Al (0.0002 – 12.4%), Pb (0.0012 – 2.07%), Si (0.0005 – 0.12%), Cu (0.0006 – 5.95%), Mn (0.0004 – 0.00524%), Fe (0.0009 – 0.41%), Ni (0.0009 – 0.27%), were obtained using standard reference samples and production samples of the alloys, the chemical composition of which was previously determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The correctness of the developed methodology was confirmed by analysis of standard samples and comparative analysis of the obtained results using the Student’s t-test.

Study on the Causes and Control Measures of Mg–Al Spinel Inclusions in U75V Heavy Rail Steel

U75V heavy rail steel production uses an aluminum-free deoxidation process; however, large particles of MgO–Al2O3 inclusions form in the steel, which has a great impact on product quality. In this paper, we try to explain how spinel inclusions, which affect the metallurgical quality of heavy rail steel, are produced by thermodynamic and experimental methods, and then determined measures for avoiding such inclusions. The formation mechanism of spinel inclusions in U75V heavy rail steel was determined through the analysis of nozzle clogging in the pouring process and typical inclusions in steel. The results show that there are two types of spinel inclusions in heavy rail steel: one is pure Mg–Al spinel inclusions and the other is Mg–Al spinel inclusions coated with calcium aluminate. The small, pure Mg–Al spinel inclusions were precipitated during the solidification of the molten steel, and the precipitation temperature was related to the composition of the molten steel. The large spinel inclusions were derived from clogging of the submersed nozzle. Mg–Al spinel inclusions coated with calcium aluminate were transformed from CaO–SiO2–Al2O3–MgO complex inclusions in the steel during cooling, and the formation temperature was related to the content of Al2O3 and MgO in the inclusions. The content of Al2O3 and MgO in the inclusions was the key to the formation of the Mg–Al spinel inclusions. Therefore, in order to control the production of spinel inclusions in steel, it is necessary to strictly control the content of impurity elements such as magnesium and aluminum in the alloy auxiliary materials, to reduce the secondary oxidation of liquid steel and to reduce the erosion of refractory materials.

Copper diffusion into epoxy under high temperature

High reliability is critical for semiconductors, especially power semiconductors, which usually work in high temperature conditions. One important reliability issue for power semiconductors is the copper diffusion into polymers. Copper diffusion accelerated polymer decomposition. Also, severe copper diffusion even causes short circuits. Although copper diffusion has been identified, the reason for the initiation of copper diffusion is still not well understood. Here, we encapsulated copper substrate with five different epoxies to investigate the reason for the initiation of copper diffusion. The influence of epoxy impurity elements and epoxy cross-link density was investigated. The results show that the initiation of copper diffusion into epoxy is highly related to the impurity elements, sulfur (S) and chlorine (Cl). In contrast, the low cross-link density of the epoxy cannot initiate copper diffusion. It implies that using S-free and Cl-free epoxy is necessary for semiconductors requiring high reliability.

Alkali-metal-based molecular-ion secondary ion mass spectrometry for precise quantitative analysis of low-dimensional materials without standards

Advancement in the understanding of fundamental aspects of Secondary Ion Mass Spectrometry (SIMS) has made this technique to be extremely powerful for quantitative materials analysis. The secondary ion emission process is a complex phenomenon involving various mechanisms to understand the mechanism. Among the existing mechanisms, the “electron-tunneling model” is the most accepted concept in the understanding of ionization probability for positive and negative ions. This model essentially concerns the survival probability of an ion emitted from the surface. As the intensity of secondary ions of a certain element depends strongly on the efficiency of ionization of a sputtered atom or molecule, the “local surface chemistry” plays a significant role in the secondary ion emission. This is purported as the “Matrix Effect” in SIMS, making the technique extremely challenging for quantification of materials in spite of the fact that it has the highest detection sensitivity (<ppb) and exceptional depth-resolution (<1[Formula: see text]nm). Therefore, it is required to correct the “matrix effect” for quantitative analysis. If the probing element (M) in its close proximity sees an alkali element (such as Li, Rb, K, Na and Cs, referred to as “A”) on the sample surface, the sputtered neutral atom (M0) of the probing element can attach an alkali-ion forming a quasi-molecular (MA)[Formula: see text] ion. Such a phenomenon can also occur if an alkali ion beam is chosen as the primary beam for sputtering. The MA[Formula: see text] molecular ion formation is directly related to the atomic polarizability of the element M. Since the sputtering of neutral atom (M0) is unconnected with the formation of MA[Formula: see text] ion, the “matrix effect” decreases dramatically in the analysis using MA[Formula: see text] ions. The phenomenon is very similar to the mechanism of “secondary neutral mass spectrometry” (SNMS). Although these (MA)[Formula: see text] molecular ions are potentially applicable in the direct quantification of materials without the need for “calibration standards”, it generally has a weak intensity. In such a case, the (MA)[Formula: see text] molecular ions are preferred in the analysis because of their higher detection sensitivity (by a few orders of magnitude in some cases), compared to that of (MA)[Formula: see text] molecular ions. Monitoring of the molecular ions is routinely preferred in conventional SIMS experiments to discriminate the sputtered ion species which are affected by mass interference or have poor dynamic ranges. For example, while making the SIMS analysis of GaAs, carbon as an impurity element is detected by monitoring (AsC)[Formula: see text] molecular ions instead of C− ions, because the C− ions have high background arising from the carbon-containing residual-gas species in the analysis chamber. Caesium is decidedly chosen for MCs[Formula: see text] or MCs[Formula: see text] molecular ions in SIMS because of the strongest reactivity and electropositive nature of caesium. This paper deals with a comprehensive discussion on the ion-emission phenomena in sputtering, the “matrix effect” and its compensation, and the potential application of the “MCs[Formula: see text]-SIMS” ([Formula: see text]) in the effective quantitative chemical analysis of materials. A special prominence has been given to the quantification of low-dimensional materials, superlattices and quantum-confined structures using this state-of-the-art “MCs[Formula: see text]-SIMS” approach in all complexities.

A simple and fast method for measurement of elemental impurities in powdered U-oxide materials by means of ns-UV laser ablation coupled to a sector-field ICP-MS

A simple and fast method for measurement of elemental impurities in powdered U-oxide materials by means of ns-UV laser ablation coupled to a sector-field ICP-MS

DEVELOPMENT OF APPROACHES TO THE ANALYSIS OF ELEMENTAL IMPURITIES IN TITANIUM DIOXIDE (BARIUM AND LEAD DEFINITION)

Relevance. Titanium dioxide (TiO2) is widely used in the pharmaceutical industry as a drug excipient (DE). Therefore, control of its content of ele-mental impurities (EI) plays an important role in ensuring the stability of quality and safety of drugs. The lack of harmonized pharmacopoeial require-ments for the content of EIs in TiO2, as well as the need for specialized validated methods of their analysis determine the actual task in the field of quality control of this substance. Research objective. This work is devoted to the development and validation of a method for the determination of barium and lead in TiO2 sub-stance. Material and Methods. The inductively coupled plasma atomic emission spectrometry (ICP-AES) method was used to determine the barium and lead content in the TiO2 substance. Acid extraction was used in the sample preparation process. All used reagents and materials were in accordance with pharmacopoeial requirements. A sample of TiO2 substance, manufactured by Venator Germany GmbH, Germany, was used as an object of study. Validation of the method was carried out in accordance with the requirements of GF RF for the following characteristics: specificity, linearity, LOQ, correctness, repeatability, intra-laboratory precision and range of the technique. Results. The method of barium and lead determination in TiO2 substance using ICP-AES demonstrates high accuracy and sensitivity. The results ob-tained during validation meet the acceptance criteria, which confirms the applicability of the technique for control of barium and lead content in TiO2 substance. Conclusions. A method for the determination of barium and lead impurities in TiO2 substance using the ICP-AES method and acid extraction during sample preparation has been developed. This approach enables the determination of barium and lead at the specification level (20 ppm and 5 ppm, re-spectively). The validation results meet the acceptance criteria for all characteristics investigated, confirming the ability to quantify barium and lead in the range of 50% to 150% of the specification level.

Thermodynamic Modeling of Solid Flux Interactions with Molten Aluminum

Oxide and dross formation during aluminum melt processing results in a considerable amount of loss of metallic aluminum. The total melt loss generated during melt processing can be greatly reduced by efficient use of flux, particularly for melting aluminum scrap or secondary alloys. Effective use of cover fluxes can significantly reduce dross generation by creating a barrier between the metallic aluminum and the atmosphere. The amount of metallic aluminum trapped within the dross layer can also be reduced by up to 50% using drossing fluxes. However, reducing the industrial average melt loss has remained difficult. To evaluate flux ingredients used in the casting industry, computational thermodynamic software ThermoCalc was used to calculate the driving force for reactions between twenty-one flux ingredients and eighteen common alloying and impurity elements in foundry alloys. The thermodynamic calculations, combined with other properties, were used to provide a desirable list of cover and drossing ingredients, which are being experimentally validated.