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Molecules (Basel, Switzerland) Aug 2022Dinotefuran (DNT) is a neonicotinoid insecticide widely used in pest control. Identification of structurally related impurities is indispensable during material...
Dinotefuran (DNT) is a neonicotinoid insecticide widely used in pest control. Identification of structurally related impurities is indispensable during material purification and pesticide registration and certified reference material development, and therefore needs to be carefully characterized. In this study, a combined strategy with liquid chromatography high-resolution mass spectrometry and SIRIUS has been developed to elucidate impurities from DNT material. MS and MS/MS spectra were used to score the impurity candidates by isotope score and fragment tree in the computer assisted tool, SIRIUS. DNT, the main component, worked as an anchor for formula identification and impurity structure elucidation. With this strategy, two by-product impurities and one stereoisomer were identified. Their fragmentation pathways were concluded, and the mechanism for impurity formation was also proposed. This result showed a successful application for combined human intelligence and machine learning, in the identification of pesticide impurities.
Topics: Chromatography, High Pressure Liquid; Drug Contamination; Guanidines; Humans; Neonicotinoids; Nitro Compounds; Pesticides; Tandem Mass Spectrometry
PubMed: 36014490
DOI: 10.3390/molecules27165251 -
Cold Spring Harbor Protocols Mar 2020Quantifying RNA is an important and necessary step before most RNA analysis techniques. Methods for quantifying RNA can be classified into two categories: ultraviolet...
Quantifying RNA is an important and necessary step before most RNA analysis techniques. Methods for quantifying RNA can be classified into two categories: ultraviolet (UV) spectrophotometric methods, which are based on the absorption spectra of the purine and pyrimidine bases; and fluorescent dye-based methods, which measure the fluorescence intensity of dyes that selectively fluoresce when bound to nucleic acids. If the RNA sample is pure (i.e., without significant amounts of contaminants such as proteins, phenol, agarose, or other nucleic acids), UV spectrophotometric measurement of the amount of UV irradiation absorbed by the bases is simple and accurate. However, if the sample contains significant quantities of impurities or if the concentration of RNA is very low, it is better to use fluorescent dye-based methods. An overview of spectrophotometric and fluorescent dye-based RNA quantification methods is given here, as are several options for storing purified RNA preparations. Proper storage of RNA samples is important; it can help minimize RNase contamination and consequent sample degradation.
Topics: Drug Storage; Electrophoresis, Agar Gel; Ethidium; Fluorescent Dyes; Freezing; Organic Chemicals; RNA; Spectrophotometry, Ultraviolet
PubMed: 32123017
DOI: 10.1101/pdb.top101709 -
Food Science & Nutrition Jul 2022Anthocyanins are a group of water-soluble polyphenolic pigments found primarily in flowers, vegetables, and fruits. These pigments play critical roles in plant and human...
Anthocyanins are a group of water-soluble polyphenolic pigments found primarily in flowers, vegetables, and fruits. These pigments play critical roles in plant and human health. Spectrophotometric methods are a simple and inexpensive way to quantify anthocyanins in plant tissues. Two main spectrophotometric methods have been developed, organic solvent-based, and pH differential methods. Both of these methods are subject to interference from light-absorbing impurities and need to be optimized for different matrixes of different plant materials. Eight methods have been tested in this experiment to quantify anthocyanins in strawberry fruits. Six organic solvent-based methods tested methanol, chloroform-methanol, and MgO in different ratios. The other two methods were pH differential method and a combination of organic solvent-based and pH differential method. Two methods used organic solvents (methanol and chloroform-methanol) were the best in extracting anthocyanin from strawberry fruits. Adding MgO increased the pH of the extract and was less efficient in anthocyanin extraction. All other methods had lower anthocyanin yield compared with methanol and chloroform-methanol methods and are not recommended for strawberry fruit anthocyanin extraction.
PubMed: 35844903
DOI: 10.1002/fsn3.2065 -
Microbiome Mar 2023Arctic snowpack microbial communities are continually subject to dynamic chemical and microbial input from the atmosphere. As such, the factors that contribute to...
BACKGROUND
Arctic snowpack microbial communities are continually subject to dynamic chemical and microbial input from the atmosphere. As such, the factors that contribute to structuring their microbial communities are complex and have yet to be completely resolved. These snowpack communities can be used to evaluate whether they fit niche-based or neutral assembly theories.
METHODS
We sampled snow from 22 glacier sites on 7 glaciers across Svalbard in April during the maximum snow accumulation period and prior to the melt period to evaluate the factors that drive snowpack metataxonomy. These snowpacks were seasonal, accumulating in early winter on bare ice and firn and completely melting out in autumn. Using a Bayesian fitting strategy to evaluate Hubbell's Unified Neutral Theory of Biodiversity at multiple sites, we tested for neutrality and defined immigration rates at different taxonomic levels. Bacterial abundance and diversity were measured and the amount of potential ice-nucleating bacteria was calculated. The chemical composition (anions, cations, organic acids) and particulate impurity load (elemental and organic carbon) of the winter and spring snowpack were also characterized. We used these data in addition to geographical information to assess possible niche-based effects on snow microbial communities using multivariate and variable partitioning analysis.
RESULTS
While certain taxonomic signals were found to fit the neutral assembly model, clear evidence of niche-based selection was observed at most sites. Inorganic chemistry was not linked directly to diversity, but helped to identify predominant colonization sources and predict microbial abundance, which was tightly linked to sea spray. Organic acids were the most significant predictors of microbial diversity. At low organic acid concentrations, the snow microbial structure represented the seeding community closely, and evolved away from it at higher organic acid concentrations, with concomitant increases in bacterial numbers.
CONCLUSIONS
These results indicate that environmental selection plays a significant role in structuring snow microbial communities and that future studies should focus on activity and growth. Video Abstract.
Topics: Bayes Theorem; Ice Cover; Seasons; Bacteria; Biodiversity
PubMed: 36864462
DOI: 10.1186/s40168-023-01473-6 -
Forensic Science International Sep 2023The organic impurity profile of 3,4-methylenedioxyamphetamine (MDA) synthesised from helional via the "twodogs" method was examined to identify route-specific and...
The organic impurity profile of 3,4-methylenedioxyamphetamine (MDA) synthesised from helional via the "twodogs" method was examined to identify route-specific and condition-specific impurities. The synthesis used a condensation reaction, followed by a Beckmann rearrangement, then Hofmann rearrangement, and then conversion to a hydrochloride salt. Two chlorinating agents were investigated for the Hofmann rearrangement reaction, trichloroisocyanuric acid (TCCA) and sodium hypochlorite. Three route-specific impurities were identified in MDA using TCCA, and two of these impurities were condition-specific such that the impurities that formed were dependent on the alcohol used as solvent. Three additional impurities were identified as non-route-specific as they have previously been identified in MDA synthesised from 3,4-methylenedioxycinnamic acid or piperonal. These non-route-specific impurities were also identified in MDA synthesised using sodium hypochlorite. No impurities were detected in MDA hydrochloride. This study identified route- and condition-specific organic impurities in MDA synthesised via the "twodogs" synthetic route using helional as starting material. The results in this study provide further understanding into the illicit synthesis of MDA and highlight the expanding nature of precursors used for illicit drug manufacture. It provides valuable information to decision makers to enact legislative measures and restrict precursors of concern.
PubMed: 37499374
DOI: 10.1016/j.forsciint.2023.111788 -
Molecules (Basel, Switzerland) Apr 2020The presence of impurities can drastically affect the efficacy and safety of pharmaceutical entities. -Aminophenol (PAP) is one of the main impurities of paracetamol...
The presence of impurities can drastically affect the efficacy and safety of pharmaceutical entities. -Aminophenol (PAP) is one of the main impurities of paracetamol (PA) that can potentially show toxic effects such as maternal toxicity and nephrotoxicity. The removal of PAP from PA is challenging and difficult to achieve through regular crystallization approaches. In this regard, we report four new salts of PAP with salicylic acid (SA), oxalic acid (OX), l-tartaric acid (TA), and (1)-(+)-10-camphorsulfonic acid (CSA). All the PAP salts were analyzed using single-crystal X-ray diffraction, powder X-ray diffraction, infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The presence of minute amounts of PAP in paracetamol solids gives a dark color to the product that was difficult to remove through crystallization. In our study, we found that the addition of small quantities of the aforementioned acids helps to remove PAP from PA during the filtration and washings. This shows that salt formation could be used to efficiently remove challenging impurities.
Topics: Aminophenols; Crystallography, X-Ray; Drug Contamination; Models, Molecular; Molecular Structure; Organic Chemicals; Pharmaceutical Preparations; Powders; Salts
PubMed: 32326160
DOI: 10.3390/molecules25081910 -
Polymers Apr 2022Pervaporation is one of the most active topics in membrane research, and it has time and again proven to be an essential component for chemical separation. It has been... (Review)
Review
Pervaporation is one of the most active topics in membrane research, and it has time and again proven to be an essential component for chemical separation. It has been employed in the removal of impurities from raw materials, separation of products and by-products after reaction, and separation of pollutants from water. Given the global problem of water pollution, this approach is efficient in removing hazardous substances from water bodies. Conventional processes are based on thermodynamic equilibria involving a phase transition such as distillation and liquid-liquid extraction. These techniques have a relatively low efficacy and nowadays they are not recommended because it is not sustainable in terms of energy consumption and/or waste generation. Pervaporation emerged in the 1980s and is now becoming a popular membrane separation technology because of its intrinsic features such as low energy requirements, cheap separation costs, and good quality product output. The focus of this review is on current developments in pervaporation, mass transport in membranes, material selection, fabrication and characterization techniques, and applications of various membranes in the separation of chemicals from water.
PubMed: 35458354
DOI: 10.3390/polym14081604 -
Chemosphere Aug 2023Plastic packaging contains residues from substances used during manufacturing, such as solvents, as well as non-intentionally added substances (NIAS), such as... (Review)
Review
Plastic packaging contains residues from substances used during manufacturing, such as solvents, as well as non-intentionally added substances (NIAS), such as impurities, oligomers, or degradation products. By searching peer-reviewed literature, we found that at least 10,259 chemicals were related to plastic packaging materials, which include chemicals used during manufacturing and/or present in final packaging items. We then summarized and discussed their chemical structures, analytical instruments, migration characteristics, and hazard categories where possible. For plastic packaging chemicals, examination of the literature reveals gas and liquid chromatography hyphenated to a variety of accurate mass analyzers based on the use of high-resolution mass spectrometry is usually used for the identification of unknown migrants coming from plastic packaging. Chemical migration from food packaging is affected by several parameters, including the nature and complexity of the food, contact time, temperature of the system, type of packaging contact layer, and properties of the migrants. A review of the literature reveals that information on adverse effects is only available for approximately 1600 substances. Among them, it appears that additives are more toxic than monomers to wildlife and humans. Neurotoxicity accounted for the highest proportion of toxicity of all types of chemicals, while benzenoids, organic acids, and derivatives were the most toxic types of chemicals. Furthermore, studies have demonstrated that hydrocarbon derivatives, organic nitrogen compounds, and organometallic compounds have the highest proportions of dermatotoxicity, and organohalogen compounds have the highest proportions of hepatotoxicity. The main contributors to skin sensitization are organic salts. This study provides a basis for comprehensively publicizing information on chemicals in plastics, and could be helpful to better understand their potential risks to the environment and humans.
Topics: Humans; Plastics; Food Contamination; Food Packaging; Mass Spectrometry; Food
PubMed: 37116723
DOI: 10.1016/j.chemosphere.2023.138795 -
Advanced Science (Weinheim,... Jan 2020Organic light emitting diodes (OLEDs) have been well known for their potential usage in the lighting and display industry. The device efficiency and lifetime have... (Review)
Review
Organic light emitting diodes (OLEDs) have been well known for their potential usage in the lighting and display industry. The device efficiency and lifetime have improved considerably in the last three decades. However, for commercial applications, operational lifetime still lies as one of the looming challenges. In this review paper, an in-depth description of the various factors which affect OLED lifetime, and the related solutions is attempted to be consolidated. Notably, all the known intrinsic and extrinsic degradation phenomena and failure mechanisms, which include the presence of dark spot, high heat during device operation, substrate fracture, downgrading luminance, moisture attack, oxidation, corrosion, electron induced migrations, photochemical degradation, electrochemical degradation, electric breakdown, thermomechanical failures, thermal breakdown/degradation, and presence of impurities within the materials and evaporator chamber are reviewed. Light is also shed on the materials and device structures which are developed in order to obtain along with developed materials and device structures to obtain stable devices. It is believed that the theme of this report, summarizing the knowledge of mechanisms allied with OLED degradation, would be contributory in developing better-quality OLED materials and, accordingly, longer lifespan devices.
PubMed: 33437576
DOI: 10.1002/advs.202002254 -
Chemosphere Mar 2022The taste and odor (T&O) problem represented by 2-methylisoborneol (2-MIB) and geosmin (GSM) in water is the multiple undesirable substances in the drinking water and...
The taste and odor (T&O) problem represented by 2-methylisoborneol (2-MIB) and geosmin (GSM) in water is the multiple undesirable substances in the drinking water and the aquatic industry. In this study, the UV-assisted photoelectrochemical, a prospective advanced oxidation process (AOP), was evaluated for the degradation of 2-MIB and GSM. In contrast to UV photochemical and electrochemical, the degradation ratio of GSM (2-MIB) increase to 96% (95%) in 25 min. The removal ratio and rate depended on reaction time, electrolyte concentration, current density, and water quality parameters (e.g. pH, HCO, natural organic matter, and tap water). Among these parameters, a high concentration of electrolyte and acidic solutions could accelerate the rate and increase the ratio, while alkaline conditions and the impurity content had negative effects. Furthermore, the significant role of various reactive species (e.g. HO∙, Cl, ClO, etc) were highlighted by scavenging experiments. Complex free radicals exist was further verified by electron paramagnetic resonance spectroscopy (EPR) experiments. The intermediates were identified and the possible degradation pathways during the UV-assisted photoelectrochemical reactions of both compounds were proposed. Overall, the UV-assisted photoelectrochemical is beneficial to the removal of GSM and 2-MIB in water.
Topics: Camphanes; Naphthols; Odorants; Prospective Studies; Water Pollutants, Chemical; Water Purification
PubMed: 34922967
DOI: 10.1016/j.chemosphere.2021.133325