Carbon contaminations on surface & sub-surface of silicon (Si) are characterized using Auger method. The surface carbon atomic % on Si of post treatment with H 3 PO 4 (for nitride etch), BOE (buffer ...HF for oxide etch) & SC1 (standard clean for organic removal) is 4.0%, 6.0% & 1.7% respectively, with significantly higher for sample of post BOE. BOE chemicals of fresh, mid-processing & end-processing baths were sampled for gas chromatography-mass spectrometry (GC-MS) analysis where significant amount of cyclopentasiloxane & benzene were detected using hexane extraction. Cyclopentatsiloxane & benzene level was reduced from 1.7 x 10 5 to 0.45 x 10 5 & 0.7 x 10 5 to 0.4 x 10 5 count per second (cps) respectively, from fresh to end-processing chemicals. This indicates that the organic impurities in the solution might have been adsorbed or incorporated into the Si layers during oxide etching process. Auger & GC-MS proved to be efficient in monitoring & controlling of organic impurities in semiconductor process.
Trace amounts of sulphion can threaten the performance and lifespan of proton exchange membrane fuel cells (PEMFCs). The fuel mainly originates from refinery hydrogen, in which methyl mercaptan ...(MeSH), ethyl mercaptan (EtSH), dimethyl sulfide (DMS) and ethyl sulfide (EMS) inevitably exist. Herein, their negative effects are investigated on PEMFC and rotating disk electrode (RDE) levels, and the poisoning mechanisms are revealed by structural characterizations and density functional theory (DFT) calculations. The result indicates that MeSH and EtSH are 1.6 times more threatening than H2S, therefore, it is essential to limit the content of MeSH and EtSH. Nevertheless, the poisoning effect of DMS and EMS is weak enough to be tolerated. Moreover, the findings that the occupation of top site on Pt (111) weakly affects the hydrogen oxidation reaction (HOR) would contribute to the design of new catalysts with stronger toxicity resistance. This work is significant for the durability improvement of PEMFCs.
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•MeSH and EtSH are 1.6 times more threatening than H2S on PEMFC.•The effect of occupation of top site on Pt (111) on the hydrogen oxidation reaction (HOR) is very weakly.•The adsorption mechanisms of MeSH, EtSH, DMS and EMS on Pt/C catalysts are given.
Various organic solvents are widely used in the manufacturing, processing, and purification of drug substances, drug products, formulations, excipients, etc. These solvents must be removed to the ...lowest amount permitted, as they do not possess any therapeutic advantages and may cause undesirable toxicities. Therefore, a rapid and sensitive analytical method for the quantitation of residual solvents is needed. The following chapter presents a static headspace gas chromatographic (HSGC) method for determining the concentration of common residual solvents in various nanoformulations. An efficient and sensitive HSGC method has been developed using PerkinElmer's headspace autosampler/gas chromatographic system with a flame ionization detector (FID) and validated according to the International Conference for Harmonization (ICH) guideline Q3C. The method validation indicates that the method is specific, linear, accurate, precise, and sensitive for the analyzed solvents. The method is suitable for the analysis of 13 residual solvents (methanol, ethanol, acetone, diethyl ether, 2-propanol, acetonitrile, 1-propanol, ethyl acetate, tetrahydrofuran, dichloromethane, chloroform, 1-butanol, and pyridine) and utilizes an Elite 624 Crossbond 6% cyanopropylphenyl, 94% dimethylpolysiloxanes column with helium as a carrier gas.
In this paper, a model is developed for calculating pH in the presence of organic impurities due to dissolution of paint and/or continuous injection of organic impurities in the sump. The model is ...implemented in the AnCheBi code for the analysis of chemical behaviors of the iodine in the containment when the pH changes during a severe accident. Validation of the model is performed with P10T2 and P11T1 experiments carried out by AECL in Canada under the BIP project. Importance analyses of the pH calculation model in the AnCheBi code are then performed with the aforementioned experimental data via Latin hypercube sampling on the reaction coefficients, sensitivity analyses of AnCheBi, and calculation of the correlation coefficients between the reaction coefficients and figure of merits (the pH and the concentrations of the various iodine species). From the importance analyses, we provide the sensitivity of the pH calculation model to the change of pH and the concentrations of the various iodine species and the reaction coefficients related with the dominant phenomena underlying the change of pH and the concentrations of the species.
The efficient removal of organic impurities in waste salts is significant for their recycling and environmental protection. The pyrolysis process of organic impurities in waste salt was investigated ...by thermogravimetric experiment to analyze the reaction kinetics characteristics. The results indicate that the pyrolysis reaction temperature range for the present waste salt is between 641.15 K and 726.22 K. The activation energy is 177.59 kJ mol−1, and the pre-exponential factor is 2.98 × 1011 s−1. Based on this, a numerical model was established to investigate the pyrolysis performance of organic impurities in practical tubular reactor. The effects of configuration and operating parameters on reaction performance and energy consumption were revealed. It was discovered that increasing the heating rate and wall temperature can accelerate pyrolysis rate but results in higher energy consumption. To balance reaction time and energy consumption, the heating rate of 15 K/min and heating temperature of 773.15 K are recommended. The content of organic impurities and bed porosity have minimal impact on the reaction rate and energy consumption, indicating that the tubular reactor has wide applicability in various working conditions. Additionally, reducing bed porosity can improve the processing rate and daily processing capacity. This paper provides a method to analyze the pyrolysis performance of organic impurities in waste salt, which is significant for designing and selecting working conditions of practical reactor for waste salt treatment.
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•Pyrolysis kinetics characteristics of organic impurities were investigated.•Reaction temperature is between 641.15 K and 726.22 K.•Activation energy and pre-exponential factor are 177.59 kJ/mol and 2.98 × 1011 s−1.•Numerical model for pyrolysis process of organic impurities was established.•Effects of parameters on reaction rate and energy consumption were investigated.
Developing analytical methods to assure and control the quality of amino acids has long been a challenge for food ingredient, dietary supplement, and pharmaceutical industries due to the high ...polarity and the absence of chromophores in many amino acids; the situation worsens further by the lack of information of impurities that could potentially be introduced during the manufacturing processes. Herein we utilize a four-step strategy including impurity identification, method development, sample analysis, and targeted impurity detection and quantitation to demystify the impurity profiles of amino acids. The effectiveness of the approach is highlighted using histidine as an example. Analysis of histidine manufacturing and degradation processes led to the identification of 12 potential impurities of histidine, including amino acids (arginine, lysine, asparagine, aspartic acid, alanine, and glycine) and non-amino acid impurities (histamine, histidinol, 4-imidazoleacrylic acid, 4-imidazoleacetic acid, β-imidazolelactic acid, and urea). A HILIC method using Poroshell 120 HILIC-Z column (2.1 × 100 mm, 2.7 µm) and a mobile phase system consisting of ammonium formate buffer at pH 3.2 in water and 0.1% formic acid in acetonitrile coupled with a single quadrupole mass spectrometer was developed for the detection and quantitation of the proposed impurities. Evaluation of 11 commercial histidine samples using the developed method revealed distinct impurity profiles, as a fingerprint for each sample; seven of the 12 proposed impurities were detected in histidine samples tested. The developed method was evaluated in terms of specificity, linearity, range, accuracy, precision, and sensitivity (LOQ: 2.5–60.6 ng/mL) for its suitability for compendial applications. Given the high degree of overlap between the proposed and the detected impurities, the approach could be utilized to strengthen USP standards for controlling the quality of histidine. Extension of the strategy to the analysis of other amino acids is currently underway.
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•Implementation of a four-step strategy for impurity profiling of histidine.•Potential impurities of histidine were proposed and verified in actual samples.•A HILIC-MS method for the determination of 12 amino acids and non-amino acids impurities was developed.
This work describes the effect of some organic impurities on the quality of zinc deposits and on the efficiency of the electrowinning process. The presence of some organics (i.e., flotation ...collectors, flocculant and lubricating oil) in the sulfate electrolyte was shown to significantly decrease current efficiency, thereby increasing energy consumption. Microscopic and texture analyses revealed that the individual addition of these organics to the electrolyte leads to the formation of pores on the deposits, variations in their grain size, and orientation changes resulting in crystallographic randomization with a trend to reorient the crystals from a “perpendicular to the plane” to an “in plane” random distribution. The Zn electrodeposit's features are expected to affect mechanical properties and, in turn, the effectiveness of the stripping operation.
•Under continuous flow, organic impurities may strongly affect Zn electrowinning.•Some organics lead to the formation of porous Zn deposits.•Some organics caused variations in the grain size of Zn deposit.•Organics may cause orientation changes of the Zn deposit.
For assessing alfuzosin hydrochloride in the presence of organic contaminants and degradants by forced breakdown products, a novel, quick, precise, sensitive, specific, and stability-indicating ...reverse-phase (RP-UPLC) approach was established. Acquity BEH C18 (50 × 2.1 mm,1.7), BEH C8 (50 × 2.1 mm,1.7), Acquity CSH C18 (50 × 2.1 mm,1.8), and Acquity BEH C18 (100 × 2.1 mm,1.7) are among the rapid liquid chromatography columns that have been investigated. Low and neutral pH buffers were also used. Furthermore, the best chromatographic separation was achieved with a Waters Acquity HSS T3 C18, 100 mm × 2.1 mm, particle size 1.8, UV detection at As a mobile phase carrier, (acetonitrile, tetrahydrofuran) is used. The final technique conditions enable excellent impurity separation, which can be used to analyse the stability of alfuzosin hydrochloride commercial samples as well as for quality control throughout production. The gradient time was about 6.5 min, and the re-equilibration time was roughly 1.5 min, allowing for more than 100 samples each day to be analysed. Aside from that, the pH sensitive analytical approach addressed in both the US and European Pharmacopoeias was explored.
A low cost ultra-high performance reverse phase liquid chromatography (RPUPLC) method has been proven for the investigation of alfuzosin hydrochloride in the existence of organic pollutants and ...decomposition products due to forced decomposition products. Attempts have been made to develop several methods for separating drugs from organic impurities. In addition, the best chromatographic separation is Waters Acquity HSS T3 C18, 100 mm × 2.1 mm, UV detection at particle size 1.8, 254 nm, and Perchloric acid (pH 3.5 with sodium hydroxide) with a mixture of organic solvents. This method was endorsed for specificity / selectivity, linearity / range, reproducibility, recovery, and reliability. They can be utilized for quality control during manufacturing and for assessing the stability of commercially available alfuzosin hydrochloride samples. With a gradient time of about 6.0 min and an equilibration time of about 2.0 min, it was possible to analyze more than 100 samples per day. In addition, the pH susceptibility analysis methods referred to in the United States Pharmacopeia and the European Pharmacopoeia were discussed. The Method was successfully validated as per ICH Q2R1 guideline.
