Methyl Tert-butyl Ether Research Articles

Enhancing the Separation Performance of Chitosan Membranes Through the Blending with Deep Eutectic Solvents for the Pervaporation of Polar/Non-Polar Organic Mixtures.

This study explores the development of chitosan-based membranes blended with three distinct deep eutectic solvents (DESs) for the pervaporation separation of methanol and methyl tert-butyl ether. DESs were selected for their eco-friendly properties and their potential to enhance membrane performance. The chitosan (CS) membranes, both crosslinked and non-crosslinked, were characterized in terms of morphology, chemical composition, wettability, mechanical resistance, and solvent uptake. Pervaporation tests revealed that incorporating DESs significantly enhanced the membranes' selective permeability toward methanol, with up to a threefold increase in separation efficiency compared to pristine CS membranes. The membranes demonstrated a strong dependence on feed temperature, with higher temperatures improving permeation flux but reducing separation factor. Crosslinking with glutaraldehyde further increased membrane selectivity by reducing free volume into the polymer matrix. These findings underscore the potential of DESs as green additives for improving the performance of biopolymer membranes, making them promising candidates for efficient and eco-friendly organic-organic separations.

Solvent Dictated Organic Transformations.

Solvent plays an important role in many chemical reactions. The C-H activation has been one of the most powerful tools in organic synthesis. These reactions are often assisted by solvents which not only provide a medium for the chemical reactions but also facilitate reaching to the product stage. The solvent helps the reaction profile both chemically and energetically to reach the targeted product. Organic transformations via C-H activation from the solvent assistance perspective has been discussed in this review. Various solvents such as tetrahydrofuran (THF), MeCN, dichloromethane (DCM), dimethoxyethane (DME), 1,2-dichloroethane (1,2-DCE), dimethylformamide (DMF), dimethylsulfoxide (DMSO), isopropyl nitrile (iPrCN), 1,4-dioxane, AcOH, trifluoroacetic acid (TFA), Ac2O, PhCF3, chloroform (CHCl3), H2O, N-methylpyrrolidone (NMP), acetone, methyl tert-butyl ether (MTBE), toluene, p-xylene, alcohols, MeOH, 1,1,1-trifluoroethanol (TFE), 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), tert-amyl alcohol and their roles are discussed. The exclusive role of the solvent in various transformations has been deliberated by highlighting the substrate scope, along with the proposed mechanisms. For easy classification, the review has been divided into three parts: (i) solvent-switched divergent C-H activation; (ii) C-H bond activation with solvent as the coupling reagent, and (iii) C-H activation with solvent caging and solvent-assisted electron donor acceptor (EDA) complex formation and autocatalysis.

Applying newly suggested simultaneous analysis of metabolomics and lipidomics into perfluorooctanesulfonate-derived neurotoxicity mechanism in zebrafish embryos

Developing methodologies for performing multi-omics with one sample has been challenging in zebrafish toxicology; however, related studies are lacking. A new strategy for the simultaneous analysis of metabolomics and lipidomics in zebrafish embryos was proposed and applied to explore the neurotoxicity mechanisms of perfluorooctanesulfonate (PFOS). Metabolite and lipid profiled simultaneously with methyl tert-butyl ether (MTBE) were compared with individual results from other extraction solvents. Behavioral alterations were measured after the zebrafish embryos were exposed to 0.1–20 μM PFOS for 5 days. The metabolite-lipid profiles of the MTBE-based strategy analyzed with optimized larval pooling size of 30 were comparable to those of other extraction solvents, indicating the feasibility and efficiency of MTBE-based multi-omics analysis. Many metabolites and lipids, which were enriched more than those previously reported, completed the toxicity pathways involved in energy metabolism and sphingolipids, improving our understanding of PFOS-induced neurotoxicity mechanism manifested by increased movement under dark conditions. Our novel MTBE-based strategy enabled the multi-omics analysis of one sample with minimal use of zebrafish embryos, thereby improving data reliability on changes in multi-layered biomolecules. This study will advance multi-omics technologies that are critical to elucidating the toxicity mechanisms of toxic chemicals including per- and polyfluoroalkyl substances.

Expression of Concern “Structural modification of graphene material by silicon mono-doping and co-doping with heteroatoms as sensors for methyl tert-butyl ether (MTBE) as a fuel additive: Insight from DFT and MD simulation” [Comput. Theoret. Chem. 1239 (2024) 114669]

Expression of Concern “Structural modification of graphene material by silicon mono-doping and co-doping with heteroatoms as sensors for methyl tert-butyl ether (MTBE) as a fuel additive: Insight from DFT and MD simulation” [Comput. Theoret. Chem. 1239 (2024) 114669]

Explosion disaster at a pharmaceutical facility in Visakhapatnam, India

An industrial accident at a red category Escientia Advanced Sciences Pharmaceutical Company at Anakapalli district on 21st August claimed 17 lives due to blast injuries and 36 others sustained various degrees of thermal injuries. A Methyl-tert butyl ether (MTBE) heavy solvent leak while transiting from the second floor to the storage tank on the ground floor resulted in a vapour cloud around the power panel located there and ignited. The fire then spread through the ducts of the air handling unit to four other modules in the production block. Thick smoke and flames engulfed the facility, hampering rescue operations. 14 fire tenders and 50 fire personnel fought the blaze for an hour before arresting the blaze and preventing it from reaching the higher floors. Skylift, boom lifts and cranes were deployed by firefighters to break the plate glass windows and extricate 13 trapped workers. Around 380 employees work two shifts at the plant and most of them escaped because they were on lunch break when the explosion started the conflagration. The injured were treated at the NTR and private hospital at Anakapalli and the evacuated to tertiary hospital in the city and the Government Medical College at Visakhapatnam. No trauma or burns centre are available at the special economic zone housing the pharma city where 120 industrial accidents and equivalent number of deaths have been reported over the past five years. A detailed enquiry has been ordered into the incident by the State Government.

Assessing the Co-Exposure Patterns of Volatile Organic Compounds and the Risk of Hyperuricemia: An Analysis of the National Health and Nutrition Examination Survey 2003-2012.

Co-exposure to multiple volatile organic compounds (VOCs) is common in daily life. However, few studies have evaluated the associations between the patterns of simultaneous exposure to multiple VOCs and the risk of hyperuricemia. This study included 7490 adults from the National Health and Nutrition Examination Survey conducted between 2003 and 2012. The K-means clustering method was applied to cluster eight kinds of VOCs in the blood into various co-exposure patterns, including benzene, bromodichloromethane, chloroform, dibromochloromethane, 1,4-dichlorobenzene, ethylbenzene, methyl tertiary-butyl ether (MTBE), and o-xylene. Binary logistic regression analysis was utilized to assess the association between single VOCs, the co-exposure patterns of multiple VOCs, and the hyperuricemia risk. Restricted cubic spline functions were utilized to investigate the non-linear relationships. Based on eight VOCs, four characteristic co-exposure patterns were generated. Compared with the low-level exposure group, the levels of volatile organic compound (VOC) co-exposure in cluster 2, characterized by relatively high levels of MTBE and moderate levels of bromodichloromethane, chloroform, and dibromochloromethane, were associated with increased hyperuricemia risk, with an odds ratio of 1.32 (1.02, 1.71). Increasing levels of bromodichloromethane and chloroform were significantly associated with an increased risk of hyperuricemia. A strong J-shaped relationship was found between MTBE and hyperuricemia. This study indicated that blood bromodichloromethane and chloroform were positively associated with hyperuricemia risk. Blood MTBE had a J-shaped association with hyperuricemia. In addition, the significant association of the co-exposure patterns of multiple VOCs in the blood with hyperuricemia risk was observed. Changing VOC co-exposure patterns may play a crucial role in the occurrence of hyperuricemia.

Impacts of MTBE in gasoline on the tailpipe ammonia emissions from China-6 certified passenger vehicles

Postcatalyst ammonia emissions from gasoline vehicles recently received attentions because of their contribution to the formation of urban secondary aerosols. To better understand whether fuel formulation would curb ammonia, the influence of methyl tertiary-butyl ether (MTBE) additive in gasoline on the tailpipe ammonia emissions from six China-6 compliant vehicles was investigated over the World Harmonized Light-duty Test Cycle (WLTC) at −7 °C and 23 °C. Ammonia emissions were measured with MTBE-free and 10 % MTBE-containing China-6 compliant gasoline fuels on the test vehicles. At – 7 °C, the ammonia emissions with and without MTBE addition ranged from 0.15 – 17.07 mg/km and 0.81 − 25.13 mg/km, respectively. At 23 °C, ammonia emissions were 0 − 7.4 mg/km for MTBE-containing fuel and 0 − 8.76 mg/km for MTBE-free fuel. More ammonia emissions were often observed as a result of maneuvering of enriched air-fuel mixtures to improve the combustion stability after cold-start and for de-NOx purpose. Due to the oxygen-containing nature of MTBE, its addition favors ammonia reduction in cold-start tests at – 7 and 23 °C. It is noted that “λ sweep”, an engine control strategy injecting extra fuel to deplete stored oxygen in the catalyst and suppress transient NOx formation during reacceleration after prolonged deceleration, may contribute to ammonia emissions due to the use of enriched air-fuel mixtures.

Elevated Urinary Levels of Fungal and Environmental Toxins in Patients with Pancreatic Ductal Adenocarcinoma

BackgroundRisk factors for pancreatic ductal adenocarcinoma (PDAC) include tobacco/alcohol abuse, genetic predisposition, insulin resistance, and pancreatic cysts. Despite these well-established risk factors and the screening of high-risk individuals, some people still develop PDAC. This study aims to explore a potential risk factor for PDAC by investigating the association between fungal toxins (FT) and environmental toxins (ET) and the disease. We predicted that individuals with PDAC would have higher levels of these toxins compared to healthy controls. The rationale behind this hypothesis is that exposure to FT and ET might contribute to the development of PDAC by elevating cancer risk.MethodsA pilot retrospective cohort study was conducted at Moffitt Cancer Center from 2022 to 2023. This study compared FT and ET levels, demographic data, and PDAC features between subjects with PDAC and healthy controls.ResultsForty subjects were enrolled in the study, comprising 20 with pancreatic ductal adenocarcinoma (PDAC) and 20 healthy controls. Baseline demographics were similar between the two groups. Among the PDAC subjects, the most common tumor location was the head of the pancreas (55%); 30% had locally advanced disease, 45% were borderline resectable, and 10% had metastatic disease.Compared to the controls, subjects with PDAC had significantly higher levels of fungal toxins (FTs) including ochratoxin, gliotoxin, and citrinin (p < 0.05). Additionally, PDAC patients had significantly elevated levels of environmental toxins (ETs) such as methyl tert-butyl ether (MTBE), xylene, styrene, acrylonitrile, perchlorate, diphenyl phosphate, bromopropane, organophosphates, acrolein, tiglylglycine, and diethylphosphate (p < 0.05).ConclusionOur study demonstrates that subjects with PDAC, without other risk factors, have higher FT and ET levels than controls. Further studies are needed to evaluate whether ET and FT exposure can be clinically utilized as a risk factor for PDAC development.

Personalization of pharmacotherapy with sirolimus based on volumetric absorptive microsampling (VAMS) in pediatric renal transplant recipients—from LC-MS/MS method validation to clinical application

BackgroundThe benefits of pharmacotherapy with sirolimus (SIR) in pediatric transplant recipients are well established. Traditionally, whole blood samples have been used to measure SIR concentrations. Volumetric Absorptive Microsampling (VAMS) is an alternative sampling strategy suitable for Therapeutic Drug Monitoring (TDM). In this study, we developed and validated two liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods for determining SIR concentrations in whole blood (WB) and capillary whole blood samples collected using a VAMS-Mitra™ device.MethodsWe used protein precipitation during WB sample preparation and dispersive liquid-liquid microextraction (DLLME) with methyl tert-butyl ether for VAMS sample preparation to optimise the analyte extraction process. The described validation protocols were cross-validated, confirming the equivalence of the whole-blood and VAMS-based methods. Furthermore, the developed methods were evaluated in two three-level rounds of an external proficiency-testing scheme.ResultsThe analytical methods were successfully validated within the calibration range of SIR (0.5–60 ng/ml). The validation parameters met the European Medicines Agency (EMA) and the International Association of Therapeutic Drug Monitoring and Clinical Toxicology (IATDM&CT) acceptance criteria. No hematocrit (tested in the range of 24.3–64.1%), matrix, or carry-over effects were observed. Cross-validation confirmed the interchangeability between VAMS-LC-MS/MS and WB-LC-MS/MS methods. The developed methods were successfully implemented for SIR determination in 140 clinical samples (70 each of WB and VAMS) from pediatric renal transplant recipients, demonstrating their practicality and reliability.ConclusionThe VAMS-based method has been rigorously tested and is clinically equivalent to the reference WB-LC-MS/MS method. Additionally, clinical validation confirmed the utility of the presented methods for TDM of the SIR in the pediatric population after renal transplantation.Graphical abstract

Liquid-Liquid equilibrium Behavior and intermolecular interactions of Levulinic acid and water with isopropyl ether and methyl Tert-Butyl ether

Levulinic acid (LA) is a crucial bio-based chemical with extensive industrial applications. Due to its significant share in the cost of production, the development of efficient techniques for the separation of LA is essential. Traditional separation using sulphuric acid raises environmental and cost concerns, making liquid–liquid extraction a more sustainable and cost-effective alternative. liquid–liquid equilibrium (LLE) investigation was carried out for two ternary mixtures of water + LA + isopropyl ether / methyl tert-butyl ether (MTBE) at two temperatures and 101.3 kPa. The results indicated that the solvent MTBE, as an extractant, showed a higher partition coefficient and selectivity for LA than isopropyl ether, demonstrating its superior effectiveness in recovering LA. The interaction insights between LA and the extractants were explored using quantum chemistry calculations, which aligned well with the collected results. The ascertained LLE data was modeled using the NRTL equation, achieving the RMSD values below 0.01, demonstrating a good concordance between the collected data and computed values. The fitted NRTL model parameters are conducive to the designing and optimizing the LA separation process.

A-070 Evaluation of Plain and Serum-Separator Blood Collection Tubes for the Measurement of Steroid Hormones by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Abstract Background Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) is the preferred method for quantifying steroids. Commonly measured steroids 11-deoxycortisol, androstenedione, testosterone, 17-hydroxyprogesterone and dehydroepiandrosterone (DHEA). Although serum separator blood collection tubes may not be recommended but their frequent use is attributed to the ease of serum separation. Moreover, the serum separator tube may be the only available option for analysis, without the need for additional sample collection. Under such conditions, from certain serum separator tubes, we observed occasional interference in LC-MS/MS steroid method. We pursued to evaluate the performance of blood collection tubes without and those with serum separators, for the quantification of specified steroids by LC-MS/MS. Methods Blood samples were collected from 10 volunteers using both plain and serum separator blood collection tubes procured from two major suppliers (Greiner and BD). The specified steroids were measured by LC-MS/MS method. The procedure involved addition of labeled internal standards to the samples and extraction of steroids in methyl tert-butyl ether. Subsequently, the extract dried under a stream of nitrogen, and the residue was reconstituted in the mobile phase. LC-MS/MS analysis involved multiple reaction monitoring (MRM) for the specified steroids and their internal standards. Results The figure shows a sample chromatogram from a subject with blood samples collected in a plain (A) and serum separator tubes from Greiner (B) and BD (C1 and C2, a zoomed of C1). In this sample, from the plain tube, the concentrations of 11-deoxycortisol, androstenedione, testosterone, 17-hydroxyprogesterone and DHEA were 27, 55, 690, 99 and 283 ng/mL respectively. No significant interference was observed in Greiner serum separator tube. Whereas BD serum separator tube exhibited several erroneous peaks making the quantitation of several steroids challenging or inaccurate. Conclusions In the described LC-MS/MS method, BD serum-separator tubes exhibited erroneous peaks. These peaks were not seen in Greiner serum-separator tubes.

Thermodynamic excess properties of the methyl tert-butyl ether + benzene + cyclohexane ternary system and its binary subsystems at temperature T = (293.15, 298.15, 303.15, and 313.15) K and ambient pressure

ABSTRACT This work reports for the first time, the experimental densities and sound speeds for the ternary system {methyl tert-butyl ether + benzene + cyclohexane} within the temperature range (293.15 to 313.15) K and under ambient pressure conditions. The related binary subsystems have also been reported. Experimental data were used to derive excess molar volumes and excess isentropic compressibilities. Redlich-Kister and Cibulka’s equations correlated the binary and ternary excess properties, respectively, with standard deviations falling below the estimated uncertainties of the corresponding properties. The results have been interpreted in terms of molecular interactions between mixtures’ components and structural effects. Additionally, two symmetric (Kohler and Muggianu) and two asymmetric (Hillert and Toop) binary contribution models have been tested for their ability to predict the excess properties of the ternary excess properties.

A broad-spectrum LC-MS/MS method for screening and quantification of 100 analytes in clinical and autopsy blood samples

Liquid chromatography coupled with mass spectrometry (LC-MS) has been tremendously used for screening purposes in forensic toxicology, because of their great adaptability and reasonable time/resource consumption. Herein, a fully validated method based on liquid-liquid extraction (LLE) in human whole blood, by a multiple reaction monitoring (MRM) analysis through LC-MS/MS, is described. The proposed method simultaneously detects 100 analytes (plus three deuterated internal standard compounds) belonging to many different classes, including drugs of abuse, prescription and over-the-counter drugs commonly involved in poisoning and medical malpractice cases in our territory, as well as certain new psychoactive substances (NPS) and toxic substances potentially associated with adverse effects. The optimised LLE employs one extraction step of 200 μL blood using 0.1 M HCl methyl-tert-butyl-ether (MTBE) (acidified with concentrated HCl) proved to be suitable for the extraction of basic and neutral substances; as a reconstitution solvent a mixture of 88:12v/v, 0.1 % formic acid in 10 mM aqueous ammonium acetate, pH 3.5: 0.1 % formic acid in acetonitrile was used, yielding satisfactory recoveries for all analytes. The method was sensitive, showing low LOD/ LOQ for all substances ranging from 0.01 to 5/ 0.05–20 ng/mL, respectively. Linearity ranged between 0.05–500 ng/mL (R2 = 0.9811–0.9995), and the inter- and intra-day precisions ranged between 3–15 % and 7–18 %, respectively. Accuracy was evaluated in terms of percentage recovery, lying within acceptable range. The matrix effect expressed as ion suppression/enhancement of each analyte was in the range ±25 % for all analytes. Post-preparative stability of analytes was higher than 85 %, while no carryover between runs was observed. The developed method has been successfully applied in routine toxicological analyses for the analysis of biological samples from clinical and autopsy cases.

389 Impact of a Controlled Internal Drug Release device on circulating and local concentrations of progesterone

Abstract Controlled Internal Drug Release (CIDR) devices have become an important component of reproductive management programs in many beef herds. When a CIDR is inserted into a cow, circulating concentrations of progesterone mimic a functional corpus luteum. Some data, however, suggest that concentration of progesterone following insertion of a CIDR might have negative consequences on fertility in Bos indicus animals. Therefore, the objective of this study was to determine the impact of a CIDR device on circulating and uterine tissue concentrations of progesterone. A blood sample and a uterine biopsy were collected from non-suckled postpartum cycling Brahman cows (n = 10; Cycling) during the midluteal stage. A blood sample and a uterine biopsy were also collected from non-suckled postpartum cycling Brahman cows (n = 9; CIDR) after a CIDR had been in place for 5 d. To collect uterine biopsies from CIDR cows, the uterine biopsy tool was placed inside a plastic covering, both were passed into the cervix of the cow before the tool was extended through the covering and into the uterus. After the biopsy was collected, the tool was carefully removed to prevent sample contamination. Blood samples were centrifuged, and serum was collected to determine concentrations of progesterone. Uterine biopsies were snap frozen until extraction. Biopsies were weighted, thawed, and homogenized in assay buffer. Samples were then extracted with methyl tert-butyl ether and resuspended in assay buffer. Serum concentrations are reported as ng/mL and uterine concentrations are reported as ng/g. Statistical analysis was performed using the GLM procedure in SAS with treatment (CIDR vs Cycling), tissue type (uterine vs serum) and their interaction included in the model. There was a significant effect of treatment (P = 0.0062), tissue (P = 0.0063) and a treatment by tissue interaction (P = 0.0068). Animals with a CIDR had greater concentrations of progesterone than Cycling animals (274.77 vs 4.37 ng, respectively). Uterine samples had greater concentrations of progesterone than serum samples (274.40 vs 4.74 ng, respectively). These increased concentrations of progesterone were mainly from CIDR uterine samples (543.24 ng/g) which had greater (P &amp;lt; 0.001) concentrations of progesterone compared with all other samples, which did not differ from each other (P &amp;gt; 0.98; CIDR Serum 6.29 ng/mL, Cycling Serum 3.2 ng/mL, and Cycling Uterus 5.54 ng/g). In summary, CIDRs increased circulating concentrations of progesterone sufficient to keep animals from exhibiting estrus, and were not different from cows in the midluteal stage of their cycle. Local concentrations in uterine tissue; however, were significantly greater when a CIDR was in place compared with uterine tissue collected during the midluteal phase. The implications of these significantly greater concentrations of progesterone in uterine tissue warrant further investigation.

Kinetic insights into double-branched acyclic ether: Methyl tert-butyl ether and 2,2-dimethoxypropane

This study presents the first kinetic mechanism for methyl tert-butyl ether (MTBE) containing low-temperature chemistry, as well as the first mechanism for 2,2-dimethoxypropane (DMP). The mechanisms have been validated against ignition delay time experiments conducted in a high-pressure shock tube and rapid compression machine. The rapid compression machine conditions were set to 20 and 40 bar for MTBE, and 10 and 20 bar for DMP in a temperature range of 584 to 946 K. Shock tube experiments have been performed for DMP at 20 and 40 bar for stoichiometric and fuel-lean conditions in air at temperatures ranging from 913 to 1173 K. A pronounced negative temperature coefficient regime with two-stage ignition has been observed for both fuels. The developed mechanism consists of reaction rate constants that were primarily modeled in analogy to iso-octane and dimethoxymethane, and calculated thermodata on the G4//B3LYP-D3BJ/def2-TZVP level of theory. Simulations have been performed to analyze the fuel oxidation at different temperatures. Over the full temperature range, H-atom abstraction occurs mainly on the α-side for DMP and on the β-side for MTBE. At low temperatures, both fuels isomerize to the peroxy radical. The dominant MTBE radicals then tend to produce cyclic ether, while the DMP radicals react with O2, enabling significant chain branching and explaining the higher reactivity of DMP. With rising temperature, β-scission of the fuel radicals and unimolecular elimination reactions start to dominate the oxidation process.Novelty and Significance StatementThe novelty of this research is the first observation of a two-stage ignition of methyl-tert butyl ether (MTBE) in an RCM and a discussion of its fundamental ignition chemistry, which is based on a developed detailed kinetic mechanism. In addition, 2,2-dimethoxypropane (DMP) has been investigated experimentally and theoretically to explain the difference in reactivity to MTBE despite their strong molecular similarity. The experiments include RCM and shock tube experiments. The kinetic model is based on rate constant analogies and newly calculated thermo data on the G4//B3LYP-D3BJ/def2-TZVP level of theory. This work is significant, as MTBE is still a widely used octane booster and the developed model could help to improve engine simulations. Furthermore, the findings of DMP provide insights into future fuel design.

Distribution and Risk Assessment of VOCs in Road Dust Across Different Urban Areas

ABSTRACT Volatile organic compounds (VOCs) are significant pollutants in urban road dust, but their distribution and associated health risks remain unclear. VOC distribution in road dust from six distinct urban areas in Beijing Daxing District, China was systematically investigated. Eighteen VOCs were detected, with the highest load in commercial areas (7.73 μg/g), followed by industrial parks (6.38 μg/g), residential areas (3.35 μg/g), leisure areas (2.79 μg/g), traffic areas (2.01 μg/g) and urban-rural fringe (1.85 μg/g), much lower than in air and water phases. Typical VOCs in road dust include methyl tertiary butyl ether (MTBE) (0.82–1.24 μg/g), benzene series compounds (0.02–4.19 μg/g) and volatile halogenated alkanes (0.002-0.095 μg/g). Incomplete combustion of road vehicle fuels is the key source of VOCs. Particular attention was given to VOCs in typical sites within the urban-rural fringe, known for their unique pollution characteristics. The VOCs loads were ranked as follows: Gas Stations (2.61–2.62 μg/g) > Intersection (1.41 μg/g) > Main Road (1.34 μg/g) > University Gate (1.27 μg/g). Increased vehicle activity and frequent stalling contribute to higher VOCs accumulation in road dust. Health risk assessment indicates there is no appreciable non-carcinogenic risk associated with exposure to road dust VOCs. Further research should consider VOCs in the broader environmental context, including air and water.

LIPOPHILIC SUBSTANCES OF THE ROOTS AND RHIZOMES OF LEUZEA SAFFLOWER (RHAPONTICUM CARTHAMOIDES (WILLD.) ILJIN)

The qualitative composition of lipophilic secondary metabolites in the medicinal plant leuzea safflower (Rhaponticum carthamoides (Willd.) Iljin) has been studied by gas chromatography - mass spectrometry. The roots and rhizomes of this plant species were used as the raw material. Hexane and methyl tert-butyl ether (MTBE) were used as extractants. Two extraction schemes were used (exhaustive and sequential), which allowed us to obtain more detailed information on the composition of components of the raw material. The obtained lipophilic extracts were separated into acid and neutral components by treating with NaOH and KOH solutions. The acid components were transformed into methyl ethers by treatment with diazomethane. The neutral components of the unsaponifiable residue were analysed without derivatisation. The fractions enriched with hydrocarbons, ketones, sterols, aliphatic and triterpene alcohols were obtained by chromatographic separation through a column with silica gel. A series of low-polar compounds were identified that have not been detected previously in this kind of raw material. By comparing the mass spectra obtained in the work with the available databases, the following compounds were identified: aliphatic acids with chain length 10-30 carbon atoms (including unsaturated and dicarboxylic), the compounds of cinnamic series, as well as benzoic, salicylic, sterculic, 9,10-octadecadienic and phenylpropanoic acids. More than 90 triterpene and aliphatic compounds of the unsaponifiable residue and 33 components of free and bound acids were identified. In addition to n-alkanes, the hydrocarbon fraction contains also squalene, as well as saturated and unsaturated hydrocarbons with shorter chains. Aliphatic and terpene aldehydes and ketones were detected. Highly active triterpene alcohols and ketones are represented mainly by ursane and oleanane derivatives. The major sterol component (β-sitosterol) is accompanied by cholesterol, campesterol, stigmasterol, stigmast-7-en-3-β-ol and stigmastan-3-β-ol.

TERPENE AND ALIPHATIC PRODUCTS OF SAPONIFICATION OF THE ETHER EXTRACT OF EUPHORBIA VIRGATA WALDST. ET KIT

The composition of the lipophilic components of Euphorbia virgata Waldst. et Kit. has been studied. Acidic and neutral components have been identified using gas-liquid chromatography with mass spectrometric detection (GC-MS) following alkaline hydrolysis of the whole extract. The plant material was extracted with methyl tert-butyl ether (MTBE). Total acids isolated during sample preparation were analysed after methylation with diazomethane. The composition of the neutral components of unsaponifiable residue was studied without derivatisation, but after separation by column chromatography on silica gel into the groups of substances of different polarity. As a result, aliphatic acids with the chain length 10-30 carbon atoms, including unsaturated ones, were identified by comparison with databases. In addition, two compounds rarely occurring in plant materials were detected: ricinoleic and octadeca-9-en-12-ynic acids. More than 100 triterpene and aliphatic compounds of the unsaponifiable residue and 25 components of acidic fractions were identified. The hydrocarbon fraction was determined to contain, in addition to n-alkanes, also substantial amounts of unsaturated branched hydrocarbon squalene. Highly active triterpene alcohols and ketones are mainly represented by ursane, lupane and cycloartane derivatives. The main sterol component (β-sitosterol) is accompanied by cholesterol, campesterol, stigmasterol, stigmast-7-en-3-β-ol and stigmastan-3-β-ol. A substantial contribution from euphanic compounds characteristic of the plants of the Euphorbiaceae family has been revealed.

Fast and reliable quantification of aldosterone, cortisol and cortisone via LC-MS/MS to study 11β-hydroxysteroid dehydrogenase activities in primary cell cultures

Cell culture experiments can support characterization of enzymatic activities in healthy and tumorous human tissues. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) enables simultaneous measurement of several steroids from a single sample, facilitating analysis of molecular pathways involved in steroid biosynthesis. We developed a reliable but fast method for quantification of cortisol, cortisone and aldosterone in cell culture supernatant. Validation, including investigation of matrix-matched calibration, was performed for two different cell types. Utility of the method was demonstrated in the study of 11β-hydroxysteroid dehydrogenase type 2 (HSD11B2) activity under conditions of glucocorticoid and mineralocorticoid excess in different cell types. Aldosterone, cortisol and cortisone were extracted by liquid-liquid extraction (LLE) with methyl tert-butyl ether from 1 mL of cell culture supernatant. Steroids were separated on a Kinetex biphenyl column (50 ×2.1 mm, 2.6 µm) with gradient elution of water and methanol containing 2 mM ammonium format and analysed in multiple reaction monitoring mode after positive electrospray ionization. Application of the method included cell culture experiments with two different primary cell types, human coronary artery smooth muscle cells (HCSMC) and human coronary artery endothelial cells (EC). Cells were treated with different concentrations of cortisol, aldosterone and mifepristone, a glucocorticoid receptor antagonist and quantitative PCR was performed. The method exhibits high precision (CV ≤ 6 %) and accuracy (deviation from nominal concentration ≤ 6 %) for concentrations above the limit of quantification (LoQ) which is 0.11, 0.56 and 0.69 nmol/L for aldosterone, cortisone and cortisol, respectively. Calibration curves did not differ when prepared in media or solvent. The method enabled us to confirm activity of HSD11B2 and concentration dependent conversion of cortisol to cortisone in HCSMC (median conversion ratio at 140 nM cortisol = 1.46 %). In contrast we did not observe any HSD11B2 activity in EC. Neither addition of high aldosterone, nor addition of 1 µM mifepristone had impact on glucocorticoid concentrations. Quantitative PCR revealed expression of HSD11B1 and HSD11B2 in HCSMC but not in EC. We present a fast and reliable method for quantification of cortisol, cortisone and aldosterone in cell culture supernatants. The method enabled us to study HSD11B2 activity in two different cell types and will support future experiments investigating mechanisms of target organ damage in conditions of glucocorticoid and mineralocorticoid excess.

Mechanism analysis and performance comparison of extractive distillation with different extractants for separating methyl tert-butyl ether/methanol mixture

Methyl tert-butyl ether (MTBE) is an important chemical raw material and fuel additive commonly used in the chemical industry and can form minimum boiling azeotrope with methanol (MeOH). In this article, extractive distillation processes with common-extractant (diethylene glycol, DG), counter-extractant (chlorobenzene, CB) and ionic liquid ([MIM][HSO4]) for the separation of MTBE and MeOH binary azeotrope are investigated simultaneously for the first time. Moreover, five quantum chemical calculation methods of σ-profiles, electrostatic potential, interaction energy, Hirshfeld surface and weak interaction are used simultaneously for the first time to reveal the extractive distillation mechanism of different extractants in detail. Finally, three extractive distillation processes (CED-IL, CED-DG, CED-CB) are established and optimized with total annual costs (TAC) and CO2 emissions as objectives. Their performances are comprehensively compared from the aspects of economy, environment, energy, exergy and inherent safety under the optimal conditions. The results demonstrate that, in comparison to the CED-DG process, the CED-IL process reduces TAC by 31.0%, total energy consumption (TEC) and gas emissions by 27.7%, process route index (PRI) by 36.4% and increase thermodynamic efficiency by 46.4%, while the CED-CB process increases TAC by 29.1%, TEC and gas emissions by 23.2%, PRI by 22.1% and reduce thermodynamic efficiency by 11.4%.