Chromatography-mass Spectrometry Method Research Articles

Research on digital-visual evaluation method of down fibers odor

Down is often used as a natural filler for warm clothing, but the odor of down is one of the issues that affects the performance of warm clothing applications. At present, the evaluation of down odor mostly uses the human olfactory evaluation method, which has low reproducibility and accuracy. This article first uses the method of activated carbon gas extraction/gas chromatography–mass spectrometry to identify five down odor compounds that can be detected in a stable way, as representative compounds of down odor. Then, a simple direct impregnate extraction/gas chromatography–mass spectrometry method was used to determine the exact concentration of odor compounds in down fibers. Finally, an odor level radar chart was constructed by analyzing the concentration of odor representative compounds of levels 1–5 in down. The digital visual evaluation method was composed of direct impregnate extraction combined with radar chart to judge the down odor level and compared to the human olfactory method. The results indicate that the radar chart evaluation has relatively accurate evaluation results and is more objective and accurate than the human olfactory method. This method for evaluating the odor level of down is simple and reliable, and has certain promotion and application prospects in the down production industry.

Study of the impurity composition of silicon tetrachloride by gas chromatography-mass-spectrometry

Silicon tetrachloride is a sought-after substance in the semiconductor and optoelectronics industries. High demands placed on its purity entail the need for detail information about the impurities present. The impurity composition of silicon tetrachloride obtained by different technologies (chlorination of diatomite and charcoal, disproportionation of trichlorosilane and chlorination of isotopically enriched silicon) was studied using the method of chromatography-mass spectrometry. Study of the possibility of using a DB-5MS 30 m × 0.32 mm × 0.25 μm capillary column with methylsiloxane as a stationary liquid phase to separate impurities revealed that most of the identified substances are eluted in the form of separate chromatographic peaks, which simplifies their determination. The exceptions are impurities N2, O2, Ar, as well as CO2, SiF4, and CHClF2, HCl, H2S. They were registered using the characteristic peaks of the mass spectra. To identify impurities, experimental mass spectra were compared to data from the NIST library and those known from the literature. Information on the impurity composition of SiCl4 has been expanded. It contains permanent gases, aliphatic and chlorine-containing hydrocarbons, chlorides of elements, sulfur-containing substances, and organosilicon compounds. A total of 30 compounds are identified, 19 being discovered for the first time. The mass spectrum of C2H6Cl4OSi2, which is absent in the literature, was obtained and described. For the first time, data on the impurity composition of isotopically enriched silicon tetrachloride have been obtained. A comparative analysis of the impurity composition of the samples under study was carried out and the impurities characteristic of each of them were determined. The data obtained in the study can be used in developing the technology for deep purification of silicon tetrachloride and in characterization of SiCl4 by manufacturing enterprises.

Evaluation of the Capparis Herbacea Willd's Chemistry, Antioxidant and Cytotoxic Activity.

The Capparidaceae family includes the medicinal herb Capparis herbacea Willd. The aerial and underground parts of plant C.herbacea were studied for their chemical composition, antioxidant, and cytotoxic properties. Using gas chromatography with mass spectrometric detection (7890A/5975C), 94 chemicals were identified in ethanol extract from leaves, roots, seeds, and stems of C. herbacea. Main components were (leaves) phytol 18.16%, hexanedioic acid, bis(2-ethylhexyl) ester 16.75%, vitamin E 11.95%, (roots) sucrose 13.94%, hexadecanoic acid, ethylester 22.80%, octadecanoic acid, ethylester 37.77%; (seeds) hexadecanoic acid, ethylester 13.96%, ethyl9.cis.,11.trans.-octadecadienoate 48.54%, bis(2-ethylhexyl) phthalate 9.77%; (stems) 1-propene-1,2,3-tricarboxylic acid, tributyl ester 42.69%, and tributylacetylcitrate 19.63%. Nine components were identified in the makeup of the C. herbacea sample's essential oil using the method of chromatography-mass spectrometry. The main components were (in%): T-cadinol (29.56), meta-cymene (16.12), pulegone (14.11), and σ-amorphene (12.26). Chloroform and methanol extracts of Capparis herbacia roots at concentrations of 1 mg/ml showed higher average antioxidant activity, while ethyl acetate root extract at concentrations of 0.75 and 1 mg/ml showed higher average antioxidant activity compared to gallic acid AOA. In addition, plant extracts have cytotoxic activity. Essential oils of leaves and stems, fruit and roots of Capparis herbacia plants exhibited cytotoxicity, all larvae died, and larval mortality was 96%.

Thermal conversion of aviation oils

These days, strict requirements to aeronautical equipment are imposed to enhance reliability, durability, and environmental compatibility. Aeronautical equipment operation reliability depends not only on its structural and technologic abilities, but also on the fact how aviation oils, fuels and technical fluid meet quality requirements during operation. During the aircraft engine operation, oils are subjected to the thermal impact. As a consequence, their properties and composition change which can affect the engine operation, on the whole. The most promising means of improving thermal resistance of aviation oils is developing new ones and improving available oil compositions. Therefore, it is feasible to analyze the kinetic properties of the oil thermal conversion which will make it possible to predict their resistance within the extensive temperature range. The paper investigates thermal decomposition kinetics of aviation oils MS-8P, TN-98 and TN-600 used on different types of aircraft in civil aviation of the Republic of Belarus by the method of a thermo-gravimetric analysis. The composition of oil samples has been researched into by IR spectroscopy, chromatography-mass spectroscopy methods. A comparative analysis of research results of new oils and oils drained from aircraft engines indicates that even under insignificant overheat during the operation, a change in the hydrocarbon composition occurs, and the hydrocarbon content of basic types varies to some extent. The oil thermolysis research reveals that potential overheat after engine shutdown complies with the temperatures at which the decomposition commences. Thermal conversion products of oil carbohydrates will contribute to the defect formation in friction subunits. As a result of test data processing of thermal conversion of aviation oils MS-8P, TN-98, TN-600, the principles of their decomposition as well as macrokinetic parameters, allowing us to precisely evaluate the effect of oils operation temperature conditions on their conversion rate, have been specified. It is essential while simulating the aircraft engine operation and predicting variations of oil quality properties during their operation.

Сomparative analysis of oils from carbonate sediments of Upper Usolskaya subformation and ediacarian-cambrian productive horizons in central part of Nepsko-Botuobinskaya anteclise

The focus in study of the central part of Nepsko-Botuobinskaya anteclise is concentrated on the subsalt oil and gas bearing horizons of group B (Osinsky, Upper Ust-Kutsky, Lower Ust-Kutsky, Preobrazhensky horizons) and V (terrigenous formations of Vendian age). However, higher, in the Lower-Middle Cambrian carbonate-halogen deposits, there are also promising horizons of group A (Kelorsky, Atovsky, Khristoforovsky, Balykhtinsky), oil and gas presence of a sufficient amount of the Angara-Lena stage, the northern part of the Nepsko-Botuobinskaya anteclise and adjacent structures. The paper examines the results of geochemical studies of oil samples from the Osinsky horizon (layer B1) and the nameless dolomite layer located between the salts in the lower part of the Upper Usolskaya subformation, previously considered gas-bearing at best. The conducted studies by the method of chromatography-mass spectrometry and comparison of the geochemical parameters of oils from different reservoirs show the similarity of hydrocarbon fluids of the Upper Usolskaya subformation and lower productive horizons, which makes it possible to attribute them to a single oil and gas bearing system.

Advancements in Sample Preparation Methods for the Chromatographic and Mass Spectrometric Determination of Zearalenone and Its Metabolites in Food: An Overview.

Zearalenone and its metabolites are mycotoxins generated by Fusarium species while crops are growing and can typically be found in various foods, posing a risk to human health. Governments have implemented stricter regulations concerning the permissible levels of zearalenone in food products to safeguard public health. Stricter regulations on zearalenone levels in food have been implemented. However, detecting zearalenone and its metabolites remains challenging due to sample complexity and interference. Surprisingly few reviews of sample preparation methods for zearalenone in food have appeared in the past decade. In this overview, we outline the most recent developments in the sample pre-treatment technology of zearalenone and its metabolites in food samples based on chromatography-mass spectrometry methods since 2012. This review covers some prominent technologies, such as liquid-liquid extraction-based methods, solid-phase extraction-based methods, and QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction, providing valuable insights into their advantages and limitations for potential applications. The assessment of the methods discussed, along with an overview of current challenges and prospects, will guide researchers in advancing the field and ensuring safer food quality for consumers worldwide.

Comparative study on physicochemical properties, microbial composition, and the volatile component of different light flavor Daqu.

Baijiu, a type of liquor, is known for its pure fragrance and softness. Its unique style is attributed to the complex microbial flora and flavor precursors found in Daqu. In order to elaborate the nature of light flavor Daqu to guide the baijiu production, four Daqu samples (DQ1, DQ2, DQ3, and DQ4) from Shanxi province were analyzed to determine their microbial structure, physicochemical properties, and volatile flavors using high-throughout put seqencing and headspace solid-phase microextraction/gas chromatography-mass spectrometry method in this study. The findings indicated that there were no noticeable variations in the water content and esterase activity of the four Daqu. However, the DQ2 sample had a higher acidity value and saccharifying enzyme activity, whereas DQ3 had the highest protease activity. The microbial community structure of the four Daqu was similar, with Lactobacillus and Streptophyta as the dominant bacteria, but the abundance of bacteria was different among the four Daqu. Issachenkia was a common dominant fungus genus in all samples. Rhizopus and Lichtemia were higher in DQ1 and DQ2, while Torulaspora, Aspergillus, and Candida were more prevalent in DQ4. A total of 27 volatile components were detected in the four Daqu, including esters, alcohols, ketones, aldehydes, and acids. DQ2 had the most volatile components and ethyl lactate and ethyl acetate were the most significant esters in the four samples. In conclusion, the physicochemical indicators of the four light flavor Daqu had distinct differences. There were significant variations in the abundance of bacteria and fungi, leading to differences in the volatile component content. These research findings can serve as a theoretical foundation for blending different light flavors Daqu and hold great significance in enhancing the quality of baijiu.

СПОСОБ ПОЛУЧЕНИЯ ОПТИМАЛЬНОГО СОСТАВА СМЕСЕВОГО ЭКОЛОГИЧЕСКИ ЧИСТОГО ДИЗЕЛЬНОГО ТОПЛИВА

The issue of improving the quality and finding alternative resources in the fuel sector leads to the use of environmentally friendly materials with improved characteristics. The article presents a calculation method, the purpose of which is to determine the engine-optimal composition of environmentally friendly mixed diesel fuel with improved ecological characteristics consisting of three main components: hydrotreated diesel fuel, biodiesel obtained by transesterification and biodiesel obtained by hydrotreating of vegetable oils. During the work, the individual characteristics of the components were determined. Those characteristics are required to be in compliance with the requirements for diesel fuels (density, viscosity, lubricating properties, sulfur content, cetane number). The qualitative and quantitative composition was investigated by chromatographymass spectrometry method. Classes of hydrocarbons and their specific representatives in each of the components were determined. Using the results of the previous stages, the calculation of the optimal composition of the components was performed using the Ansys Reaction Workbench software. The algorithm for entering the necessary initial data for working with the program, utility-aided calculation of the coefficients of dependencies of individual and thermodynamic properties of substances used in calculations were considered, thereby complementing the basic library of chemical compounds for Ansys Surrogate Blend Optimizer. As a result, a group composition for hydrocarbons was obtained that meets the requirements of the standards for further calculation of the optimal component composition. The usage of mixed diesel fuel that meets GOST R 52368-2005 "EURO diesel fuel Specifications" will not only improve the performance characteristics required in modern diesel vehicles, but also meet the standards of environmental parameters when using it. The appliance of mathematical models for calculating the optimal composition of fuels makes it possible to predict the properties of mixed compositions without experimental determination of the properties and without spending additional resources.

The Use of Liquid Chromatography and Mass Spectrometry to Identify and Quantify Chemical Components in Tea Extracts

A fast, straightforward, efficient, and high throughput reverse-phase high-performance liquid chromatography and electrospray ionization mass spectrometry method has been developed to analyze tea extracts containing polyphenols. The polyphenols detected in green tea (GT), black tea (BT), and paradise tropical tea (PTT) were separated in 18 min at wavelengths 254 nm, 260 nm, and 280 nm with a gradient elution on the RP-HPLC system. Our approach detected, identified, and quantified three catechins in the tea extracts analyzed, and the response at 280 nm wavelength was the best. The ESI-MS data confirmed the fragmentation patterns of the catechins detected in the tea extract. The validation data showed that the limit of detection (LOD) and limit of quantitation (LOQ) of catechins ranged from 5.26 ± 0.02 to 36.44 ± 0.02 ppb, and 17.52 ± 0.03 to 121.45 ± 0.16 ppb, respectively, for six catechins studied. The standard addition calibration approach used to quantify the catechin content in the tea extract simultaneously showed that PTT has a higher catechin content than GT and BT. The content of polyphenols in GT, BT, and PTT are summarized. This approach holds great promise for quality control studies to quantify polyphenols in nutritional products.

Serum metabolomic profiling for patients with adenocarcinoma of the esophagogastric junction.

The incidence of adenocarcinoma in the esophagogastric junction (AEG) has increased in the recent years. AEG is reported to have a worse prognosis compared with tumor confined to the stomach (non-AEG). Although the metabolic changes of non-AEG have been investigated in extensive studies, little effort focused on the metabolic profiling of AEG serum. Here we report an untargeted gas chromatography-mass spectrometry (GC-MS) method to explore the abnormal metabolism underlying AEG. GC-MS-based untargeted metabolomics approach combined with multivariate statistical analyses were used to study the metabolic profiling of serum samples from AEG patients (n = 70), non-AEG patients (n = 70) and health controls (n = 71). A novel serum metabolic profiling of 18 metabolites from patients of AEG and non-AEG was indicated, in comparison with health controls. Moreover, AEG and non-AEG were also well-classified with 9 distinguishing metabolites including hypoxanthine, alanine, proline, pyroglutamate, glycine, lactate, succinic acid, glutamate and kynurenine, which produced a discriminatory model with an area under the Receiver Operating Characteristic (ROC) curve of 0.852, suggesting a distinct metabolic signature of AEG. Importantly, lactate and glutamate disclosed outcome-prediction values by multivariate cox-proportional hazard model and Kaplan-Meier method based on follow-up information for 2-5years. This is the first metabolomics study to identify serum metabolic signature of AEG. The distinguishing metabolites show a promising application on clinical diagnose and outcome prediction, and allow us to unveil several key metabolic variations coexisting in AEG, which may aid to understand the underlying metabolic mechanisms.

Why does an obligate autogamous orchid produce insect attractants in nectar? \u2013 a case study on Epipactis albensis (Orchidaceae)

BackgroundThe flowers of some species of orchids produce nectar as a reward for pollination, the process of transferring pollen from flower to flower. Epipactis albensis is an obligatory autogamous species, does not require the presence of insects for pollination, nevertheless, it has not lost the ability to produce nectar, the chemical composition of which we examined by gas chromatography-mass spectrometry (GC–MS) method for identification of potential insect attractants.ResultsDuring five years of field research, we did not observe any true pollinating insects visiting the flowers of this species, only accidental insects as ants and aphids. As a result of our studies, we find that this self-pollinating orchid produces in nectar inter alia aliphatic saturated and unsaturated aldehydes such as nonanal (pelargonal) and 2-pentenal as well as aromatic ones (i.e., syringaldehyde, hyacinthin). The nectar is low in alkenes, which may explain the absence of pollinating insects. Moreover, vanillin and eugenol derivatives, well-known as important scent compounds were also identified, but the list of chemical compounds is much poorer compared with a closely related species, insect-pollinating E. helleborine.ConclusionAutogamy is a reproductive mechanism employed by many flowering plants, including the orchid genus Epipactis, as an adaptation to growing in habitats where pollinating insects are rarely observed due to the lack of nectar-producing plants they feed on. The production of numerous chemical attractants by self-pollinated E. albensis confirms the evolutionary secondary process, i.e., transition from ancestral insect-pollinating species to obligatory autogamous.

A Study of some Morphological and Essential Oil Characteristics of Spartium junecum L.

Spartium junecum L. was collected from Baksa in Lattakia, Syria, and studied morphologically depending on characteristics of plant life-form, flowers, leaves, fruits and seeds according to specialized floras, in addition to some characteristics of stomata types, trichomes, pollen grains and fibers that have been demonstrated by this study. The study of the leaves stomata confirmed the presence of 4 types, namely; anisocytic, isotricytic, brachyparahexacytic, and tetracytic. The type of trichomes was the same in all the studied areas, which is: non-glandular trichomes with different densities. Pollen grains were, tricolpate, triangular, the dimensions of the polar axis and equatorial axis were (35µm), and (31µm), respectively. Spartium junecum L. cellulose fibers were extracted by DiCoDe method (digestion–compression–decompression). The morphology of the obtained fibers was studied by optical microscopy (OM). The results showed that Spartium junecum L. fibers are elementary fibers arranged in bundles. The diameter of a single elementary fiber ranged from 7 to 10μm approximately, while the diameter of the whole bundle was about (50μm). The cross-sections showed an irregular polygonal shape with a very much characterized lumen. The essential oil isolated by hydrodistillation from the dried flowers of Spartium junceum L. was investigated by Gas Chromatography-Mass spectrometry (GC/MS) method. The GC/MS analysis of the oil revealed the presence of 6 constituents, of which heptacosene (28.75%), 3-ethyl-5-(2-ethylbutyl)-octadecane (22.45%), heptacosane (21.2%) and heneicosane (18.82%) were the major compounds constituting altogether almost 91.22% of the total composition.

Insight into the Aroma Profile and Sensory Characteristics of ‘Prokupac’ Red Wine Aromatised with Medicinal Herbs

Autochthones grape variety of ‘Prokupac’ (Vitis vinifera L.) is being increasingly cultivated in the Republic of Serbia and is one of the predominant varieties in the vineyards of southern Serbia. ‘Prokupac’ grapes are used to produce red wine with specific and distinctive varietal aromatic characteristics. Medicinal herbs can be effectively combined in alcoholic beverages. The aim of this study was to evaluate the effect of medicinal herbs on the aroma profile and sensory characteristics of ‘Prokupac’ red wine. The analysis of the aromatic composition was conducted on ‘Prokupac’ wine (control) and ‘Prokupac’ wine aromatised with selected medicinal herbs: anise (Pimpinella anisum L.), cinnamon (Cinnamomum verum J. Presl.), wormwood (Artemisia absinthium L.) and licorice (Glycyrrhiza glabra L.). The analysis of volatile aromatic compounds in the wines, performed by the gas chromatography-mass spectrometry (GC/MS) method, identified 48 compounds that were classified in the following groups: alcohols, aldehydes, ketones, acids, ethyl esters and terpenes. Sensory analysis of wines was performed including visual, olfactory, gustatory and gustatory-olfactory perceptions. Terpenes were not identified in the ‘Prokupac’ control wine, while the highest content of all identified aromatic compounds was found in wines aromatised with anise, wormwood and cinnamon. The results indicated that selected medicinal herbs affected the composition and content of volatile aromatic compounds, as well as the sensory characteristics of analyzed wines. The unique aroma profile and pleasant taste of the wine aromatised with cinnamon contributed to its differentiation from other wines, and classification as very good wine.

A Potential Citrate Shunt in Erythrocytes of PKAN Patients Caused by Mutations in Pantothenate Kinase 2.

Pantothenate kinase-associated neurodegeneration (PKAN) is a progressive neurodegenerative disease caused by mutations in the pantothenate kinase 2 (PANK2) gene and associated with iron deposition in basal ganglia. Pantothenate kinase isoforms catalyze the first step in coenzyme A (CoA) biosynthesis. Since PANK2 is the only isoform in erythrocytes, these cells are an excellent ex vivo model to study the effect of PANK2 point mutations on expression/stability and activity of the protein as well as on the downstream molecular consequences. PKAN erythrocytes containing the T528M PANK2 mutant had residual enzyme activities but variable PANK2 abundances indicating an impaired regulation of the protein. Patients with G521R/G521R, G521R/G262R, and R264N/L275fs PANK2 mutants had no residual enzyme activity and strongly reduced PANK2 abundance. G521R inactivates the catalytic activity of the enzyme, whereas G262R and the R264N point mutations impair the switch from the inactive to the active conformation of the PANK2 dimer. Metabolites in cytosolic extracts were analyzed by gas chromatography–mass spectrometry and multivariate analytic methods revealing changes in the carboxylate metabolism of erythrocytes from PKAN patients as compared to that of the carrier and healthy control. Assuming low/absent CoA levels in PKAN erythrocytes, changes are consistent with a model of altered citrate channeling where citrate is preferentially converted to α-ketoglutarate and α-hydroxyglutarate instead of being used for de novo acetyl-CoA generation. This finding hints at the importance of carboxylate metabolism in PKAN pathology with potential links to reduced cytoplasmic acetyl-CoA levels in neurons and to aberrant brain iron regulation.

Potential of chromatography and mass spectrometry for the differentiation of three series of positional isomers of 2-(dimethoxyphenyl)-N-(2-halogenobenzyl)ethanamines.

N-(2-substituted benzyl)-2,5-dimethoxyphenethylamines often cause severe poisonings which has led to their legal prohibition in many countries. At the same time, their positional isomers can be studied as potential therapeutic drugs. In this regard, the search for various approaches to differentiate these isomers is an important practical task, the solution of which would guarantee from identification errors during laboratory analysis. In this paper, the possibilities of differentiation of isomers varying in the position of two methoxy groups in the phenylethyl part of the molecule are considered on the example of compounds of NBF, NBCl, and NBBr series by chromatography-mass spectrometry methods. Gas or liquid reverse-phase chromatography in the proposed chromatographic separation modes has demonstrated their ability to resolve this problem reliably. Data on retention indices of isomeric compounds and their derivatives can serve as an additional identification criterion for gas chromatography-mass spectrometry (GC-MS) analysis. Differentiation of NBF and NBCl isomers using electron ionization (EI) mass spectra is feasible only if both the spectrum of the compound and its N-trifluoroacetyl derivative are registered; differentiation of NBBr positional isomers under these conditions does not require obtaining the derivatives. Using electrospray ion source, the compounds can easily be differentiated based on the distinctive features of their collision induced dissociation (CID) spectra recorded at low energy values, which also does not require the synthesis of derivatives. The data presented in current paper will be useful for analysis in laboratories providing the determination of narcotic drugs.

Metabolic Characteristics of SM-1, a Novel PAC-1 Derivative, in Human Liver Microsomes

Background and Objectives: SM-1 is a new synthetic small molecule compound with antitumor activity. The metabolism of SM-1 is a key parameter that needs to be evaluated to provide further insight into drug safety and efficacy in the early phases of drug development. Methods and Results: In this study, the biotransformation process of SM-1, including the metabolic pathways and major metabolites, was investigated based on a liquid chromatography-mass spectrometry method. Upon incubation of SM-1 with human liver microsomes, five metabolites were identified, namely dihydrodiol formation (R1), hydroxylation (R2, R3, and R5), and debenzylation (R4) of SM-1, with R1 and R4 being the major metabolites. The enzyme kinetic parameters of SM-1 were determined by a liquid chromatography-tandem mass spectrometry method. The enzyme kinetics of SM-1 obeyed the Michaelis-Menten equation. The Vmax, Km, and CLint of SM-1 in HLMs were 14.5 nmol/mg protein/h, 6.32 μM, and 2.29 mL/mg protein/h, respectively. Results: The chemical inhibition studies showed that CYP450 isoenzymes were responsible for SM-1 metabolism in HLMs, and CYP3A4 was the major CYP450 isoenzyme involved in the metabolism of SM-1; these findings were confirmed by using the human recombinant CYP3A4. Conclusion: Through the identification of the biotransformation pathways and enzyme kinetics of SM-1, the metabolic enzymes for SM-1 in HLMs are characterized.

A Novel Gas Chromatography-Mass Spectrometry (Gc-Ms) Method for the Detection and Determination of Tamoxifen in Oral Fluid for Doping Control Purposes

A Novel Gas Chromatography-Mass Spectrometry (Gc-Ms) Method for the Detection and Determination of Tamoxifen in Oral Fluid for Doping Control Purposes

Simultaneous Estimation of Genotoxic Impurities 4-Nitrobenzene Trifluoride, 4-Aminobenzene Trifluoride, and Benzo Trichloride in Cinacalcet Hydrochloride by GC-MS/MS Method

The main objective of this study is to develop and validate a novel, fast, and more sensitive gas chromatography-mass spectrometry (GC-MS/MS) method for the simultaneous estimation of 4-Nitrobenzotrifluoride (4-NBTF), 4-Amino-benzotrifluoride (4-ABTF), and Benzotrichloride (BTC) impurities in Cinacalcet hydrochloride (CH). The chromate-graphic separations were performed on a DB-624, 30m × 0.32mm × 1.8µm column with injector temperature of 150°C, and mode of injection is split with asplit ratio 1: 20. The carrier gas used was helium with a flowrate 1.5 mL/min, and theinjection load was 1.0 µL. Mass spectrometry quantitation was achieved by aquadrupole analyser with EI (Electron Ionization) ion source atasource temperature of 250ºC and interface temperature of 250ºC. The retention times for 4-NBTF, 4-ABTF, and BTC were at 6.13, 6.74and 7.64min, respectively. The calibration curve was linear over the concentration ranging from LOQ level to 150 % level with the correlation coefficient (r) of > 0.99. The percentage recovery was found to be within the specified range, i.e., 70.0 to 130.0 for the three impurities. The limit of detection (LOD) was established to 0.19, 0.19, and 0.18 ppm, whereas thelimit of quantification (LOQ) was obtained to 1.14, 1.12, and 1.11 ppm for 4-NBTF, 4-ABTF, and BTC, respectively. The test solutions with impurities were found to be stable in the diluent for 24 hours. A simple GC-MS/MS method was developed and validated for simultaneous estimation of three impurities in CH. The method was accurate, precise, linear, specific, sensitive, robust, and rugged as per ICH guidelines. The method has been applied to the real-time batch analysis and found to be suitable for routine quality control analysis of CH.

Determination of Hexabromocyclododecane in Expanded Polystyrene and Extruded Polystyrene Foam by Gas Chromatography-Mass Spectrometry.

A gas chromatography-mass spectrometry (GC/MS) method for the determination of hexabromocyclododecane (HBCD) in expanded polystyrene and extruded polystyrene foam (EPS/XPS) was developed. The EPS/XPS samples were ultrasonically extracted with acetone and the extracts were purified by filtration through a microporous membrane (0.22 μm) and solid-phase extraction. The samples were analyzed using a GC/MS using the selected ion monitoring mode. The ions 157, 319 and 401 were selected as the qualitative ions, while ion 239 was chosen as the quantitative ion. An HBCD standard working solution with a concentration range of 1.0–50.0 mg/L showed good linearity. The detection limit of HBCD was 0.5 mg/kg, meeting the LPC limit (<100 or 1000 mg/kg). Six laboratories were selected to verify the accuracy of the method, and 10 samples were tested. The interlaboratory relative standard deviation range was 3.68–9.80%. This method could play an important role in controlling HBCD contamination in EPS/XPS.

Aspergillus flavus originated pure compound as a potential antibacterial

Problem BackgroundPenicillin was the first and most famous fungal secondary metabolite used as broad spectrum antibiotic that revolutionarised pharmaceutical research and also saved millions of lives. The over optimistic belief in 1967 that sufficient antibiotics had been discovered to defeat infectious diseases was quickly crashed with the appearance of multidrug resistant (MDR) bacteria in 1990s. This has posed a serious threat to mankind. Although scientists are making efforts to synthesize and discover new antibiotics there are not enough new drugs in pharmaceutical pipeline to beat the pace at which MDR bacteria are emerging. In view of this there is an urgent and serious medical need for new bioactive compounds to be discovered to treat infections caused by MDR pathogens. The present study is aimed to investigate the antibacterial potential of Aspergillus flavus originated compounds that may act as drug leads to treat future infections.MethodologyAmong the 6 isolated fungal strains from the rhizosphere of Mentha piperetta, one was processed for isolation of secondary metabolites on the basis of preliminary antibacterial testing. Observation of morphological and microscopic features helped in identification of the fungal strain as Aspergillus flavus. Potato Dextrose Agar (PDA) medium was used for fungal growth while Czapec Yeast Broth (CYB) medium was used for production of fungal metabolites. Column chromatography technique was utilized for purification of compound from crude fungal extract and the mass of the compound was determined using Liquid Chromatography Mass Spectrometry (LCMS) method. Structure elucidation of the pure compound was performed using 500 Varian Nuclear Magnetic Resonance (NMR) machine. Docking was performed using Glide SP algorithm. Agar well diffusion method was used to determine the invitro antibacterial potential of the compound against two MDR bacterial strains i.e. Staphylococcus aureus and Proteus vulgaris. For this a total of 4 dose concentrations i.e. (100, 250, 500, 1000 μg mL− 1) of the compound were prepared and applied to bacterial strains on Mueller Hinton agar using tetracycline as control.ResultsThe chemical name of the purified compound from A. flavus was determined as (2E)-3-[(3S, 4R)-8-hydroxy-3, 4-dimethyl-1-oxo-3, 4-dihydro-1H-2- benzopyran-7-yl] prop-2-enoic acid with the formula C14H14O5 and exact mass of 262.08. The in-Silico analysis showed that this compound has the potential to inhibit the binding pocket of S. aureus TyrRS (1JII) with docking score of − 8.67 Kcal mole− 1. The results obtained from invitro experiments were encouraging as at 1000 μg mL− 1 the compound showed 58.8% inhibition against S. aureus and 28% inhibition against P. vulgaris.ConclusionsThe pure compound with formula C14H14O5 and exact mass of 262 exhibited antibacterial potential both insilico and invitro against both Gram negative and Gram positive bacteria. The compound was more active against S. aureus in comparison to P. vulgaris. From the obtained results it is concluded that this compound can be used as potent antibacterial candidate but further studies will be needed prior to its use as antibiotic.