Methyl Tert-butyl Ether Research Articles

Analysis of tetrabromobisphenol A and bisphenol A in plant sample-method optimization and identification of the derivatives.

Tetrabromobisphenol A (TBBPA) is the most abundant brominated flame retardant and bisphenol A (BPA) is often identified as the metabolic product of TBBPA. Both of them are highly bioconcentrated and show serious biological toxicity. In this study, an analytical method was optimized to simultaneously determine TBBPA and BPA in plant samples. Moreover, the uptake and metabolism of TBBPA in maize were investigated through hydroponic exposure experiment. The whole analysis procedure included ultrasonic extraction, lipid removal, purification by solid-phase extraction cartridge, derivatization, and detection by GC/MS. Optimizations were conducted for each pretreatment step above. After improvement, methyl tert-butyl ether (MTBE) was chosen as the extraction solvent; the lipid removal was conducted by repartition between organic solvent and alkaline solution. The best suitable pH condition is 2-2.5 for the inorganic solvent before used for further purification by HLB and silica column with the optimized elute solvent of acetone and mixtures of acetone and hexane (1:1), respectively. The recoveries of TBBPA and BPA spiked in maize samples were 69±4% and 66±4% with the relative standard deviation less than 5%, respectively, for the entire treatment procedure. Limits of detections were 4.10 ng/g and 0.13 ng/g for TBBPA and BPA in plant samples, respectively. In the hydroponic exposure experiment (100 μg/L, 15 d), the concentrations of TBBPA in maize cultivated in pH 5.8 and pH 7.0 Hoagland solutions were 1.45 and 0.89 μg/g in roots and 8.45 and 6.34 ng/g in stems, while they were all below the detection limit for leaves, respectively. The distribution of TBBPA in different tissues was as the following order: root>>stem>leaf, illustrating the accumulation in the root and the translocation to the stem. The uptake variations under different pH conditions were attributed to the change of TBBPA species, now that it shows greater hydrophobicity at lower pH condition as a kind of ionic organic contaminant. Monobromobisphenol A and dibromobisphenol A were identified as metabolisms products of TBBPA in maize. The efficiency and simplicity of the method that we proposed characterize its potential application as a screening tool for environmental monitoring and contribute to a comprehensive study of the environmental behavior of TBBPA.

Sensitive LC-MS/MS method for the temporal profiling of bile acids, fatty acids and branched-chain alpha-keto acids in maternal plasma during pregnancy and cord blood plasma at delivery

Background and aimsThere are significant changes to the maternal inflammatory profile across pregnancy. Recent studies suggest that perturbations in maternal gut microbial and dietary-derived plasma metabolites over the course of pregnancy mediate inflammation through a complex interplay of immunomodulatory effects. Despite this body of evidence, there is currently no analytical method that is suitable for the simultaneous profiling of these metabolites within human plasma. Materials and methodsWe developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the high-throughput analysis of these metabolites in human plasma without derivatization. Plasma samples were processed using liquid–liquid extraction method with varying proportions of methyl tert-butyl ether, methanol, and water in a 3:10:2.5 ratio to reduce matrix effects. ResultsLC-MS/MS detection was sufficiently sensitive to quantify these gut microbial and dietary-derived metabolites at physiological concentrations and linear calibration curves with r2 > 0.99 were obtained. Recovery was consistent across concentration levels. Stability experiments confirmed that up to 160 samples could be analyzed within a single batch. The method was validated and applied to analyse maternal plasma during the first and third trimester and cord blood plasma of 5 mothers. ConclusionThis study validated a straightforward and sensitive LC-MS/MS method for the simultaneous quantitation of gut microbial and dietary-derived metabolites in human plasma within 9 minutes without prior sample derivatization.

A LC-MS/MS method for determination of clenbuterol enantiomers in animal tissues and its application to the enantioselective distribution in Bama mini-pigs

ObjectivesTo establish and validate a simple and reliable analytical method for separation and determination of clenbuterol enantiomers (R-(-)-clenbuterol &S-(+)-clenbuterol) in animal tissues, and apply it to the enantioselective distribution of clenbuterol in Bama mini-pigs. MethodsA LC-MS/MS analytical method was developed and validated in positive multiple reaction monitoring mode with electrospray ionization. After perchloric acid deproteinization, samples were pretreated only by one step liquid–liquid extraction using tert-butyl methyl ether under strong alkaline condition. Teicoplanin was used as chiral selector and 10 mM ammonium formate methanol solution was used as mobile phase. The optimized chromatographic separation conditions were completed in 8 min. Two chiral isomers in 11 edible tissues from Bama mini-pigs were investigated. ResultsR-(-)-clenbuterol and S-(+)-clenbuterol can be baseline separated and accurately analyzed with a linear range of 5–500 ng/g. Accuracies ranged from −11.9–13.0% for R-(-)-clenbuterol and −10.2–13.2% for S-(+)-clenbuterol, intra-day and inter-day precisions were between 0.7 and 6.1% for R-(-)-clenbuterol and 1.6–5.9% for S-(+)-clenbuterol. R/S ratios in edible tissues of pigs were all significantly lower than 1. ConclusionsThe analytical method has good specificity and robustness in determination of R-(-)-clenbuterol and S-(+)-clenbuterol in animal tissues, and can be used as a routine analysis method for food safety and doping control. There is a significant difference in R/S ratio between pig feeding tissues and pharmaceutical preparations (racemate with R/S ratio of 1), which makes it possible to identify the source of clenbuterol in doping control and investigation.

Pyrolysis behaviors of di-tert-butyl peroxide in gas and liquid phases: A ReaxFF molecular dynamics simulation

Di-tert-butyl peroxide (DTBP) is widely used for various purposes, including as an initiator, vulcanizator, and fuel additive, but is susceptible to triggering fires and explosions owing to its high thermal risk. Therefore, understanding its atomistic pyrolysis mechanisms is of great importance. In this work, the pyrolysis of DTBP is investigated using ReaxFF molecular dynamics simulations with a validated reactive force field. The effect of temperature on the pyrolysis of DTBP is first investigated, followed by the product and intermediate distributions. The results reveal that the system density is crucial in the pyrolysis behaviors of DTBP. The pyrolysis products of gaseous DTBP are found to be acetone, ethane, and methyl tert-butyl ether, while those of liquid DTBP include acetone, tert-butanol, methyl tert-butyl ether, methane, 2-methoxypropene, isobutene, and methyl ethyl ketone, which is in reasonable agreement with the results of previously reported experiments. The detailed reaction pathways are then analyzed. In the initial reactions, the tert-butoxy radical ((CH3)3CO⋅) is generated by the homolysis of the O–O bond in all cases. In comparison to the gaseous phase, where the majority of subsequent reactions involve the decomposition of (CH3)3CO⋅, the liquid phase exhibits additional H-abstraction reactions leading to the formation of tert-butanol. This can be attributed to a stronger interplay between the radicals in the liquid environment. The findings from this work are anticipated to contribute valuable data for enhancing the process safety of DTBP.

Distribution, source identification, and health risk of emerging organic contaminants in groundwater of Xiong'an New Area, Northern China

Groundwater contamination in China has been greatly concerned due to dramatically increasing fresh water demand accompanied by economic development. However, little is known about aquifer vulnerability to hazardous matters especially in previously contaminated site of rapidly urbanizing cities. Here, we collected 90 groundwater samples from Xiong'an New Area during wet and dry seasons of 2019 and characterized the composition and distribution of emerging organic contaminants (EOCs) in this strategically developing city. A total of 89 EOCs, assigned to organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and volatile organic compounds (VOCs), were detected with the frequencies ranging from 1.11 %–85.6 %. Methyl tert-butyl ether (16.3 μg/L), Epoxid A (6.15 μg/L), and α-Lindane (5.15 μg/L) could be identified as major contributors to groundwater organic pollution. Significant aggregation of groundwater EOCs along Tang River were found due to historical residue and accumulation from wastewater storage there before 2017. Significant seasonal variations (p < 0.05) in the types and concentrations of EOCs could be attributed to discrepant pollution sources between varying seasons. Human health effects from exposure to groundwater EOCs were further evaluated with negligible risk (<10−4) in most samples (97.8 %) and notable risk (10−6–10−4) in several monitored wells (2.20 %) located along Tanghe Sewage Reservoir. This study provides new evidences for aquifer vulnerability to hazardous matters in historically contaminated sites and is of significant to groundwater pollution controlling and drinking water safety for rapidly urbanizing cities.

Preparative Fractionation of Phenolic Compounds and Isolation of an Enriched Flavonol Fraction from Winemaking Industry By-Products by High-Performance Counter-Current Chromatography.

High-performance counter-current chromatography (HPCCC) was used as a tool for the isolation and fractionation of phenolic compounds (PCs) in extracts from wine lees (WL) and grape pomace (GP). The biphasic solvent systems applied for HPCCC separation were n-butanol:methyl tert-butyl ether:acetonitrile:water (3:1:1:5) with 0.1% trifluoroacetic acid (TFA) and n-hexane:ethyl acetate:methanol:water (1:5:1:5). After refining the ethanol:water extracts of GP and WL by-products by ethyl acetate extraction, the latter system yielded an enriched fraction of the minor family of flavonols. Recoveries of 112.9 and 105.9 mg of purified flavonols (myricetin, quercetin, isorhamnetin, and kaempferol) in GP and WL, respectively, from 500 mg of ethyl acetate extract (equivalent to 10 g of by-product) were obtained. The HPCCC fractionation and concentration capabilities were also exploited for the characterization and tentative identification of constitutive PCs by ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS). In addition to the isolation of the enriched flavonol fraction, a total of 57 PCs in both matrixes were identified, 12 of which were reported for the first time in WL and/or GP. The application of HPCCC to GP and WL extracts may be a powerful approach to isolate large amounts of minor PCs. The composition of the isolated fraction demonstrated quantitative differences in the individual compound composition of GP and WL, supporting the potential exploitation of these matrixes as sources of specific flavonols for technological applications.

Effect of Blending Aromatic and Oxygenates Additives with Fuels to Enhance Fuel Properties

This work aims to show the influence of several oxygenates and aromatic additives in different types of unleaded fuels in the Kurdistan region of Iraq on upgrading the physicochemical properties of blends. Consuming super-grade gasoline as a fuel for automotive cars can produce large amounts of environmental emissions, a severe global problem, especially in the Kurdistan region in recent years. The physicochemical properties of mixtures, such as the research octane number (RON), Motor Octane number (MON), density, and distillation curves, will be tested by using ERASPEC spectroscopy as a fuel properties analyzer. As a result, the blending process has improved the gasoline grade to super grade by enhancing the physicochemical properties of blends. The additives used in this work as oxygenators are; Ethanol and Methyl Tertiary Butyl Ether (MTBE) added to two base fuels, light Naphtha, and unleaded Gasoline, in various ratios of (5%, 10%, 15% and 20%). An aromatic component (Aniline) is also mixed with light Naphtha and base gasoline in low concentrations (1%, 3%, and 5%). The results of blending Ethanol, MTBE, and Aniline with fuels demonstrate that the Research Octane Number RON and Motor Octane Number MON of fuels increase with the addition of different ratios of all-octane boosters. The best-recorded result of both types of octane numbers (13 points increased from the bases) is recorded by blending 3% of Aniline with the fuels. However, Ethanol can provide a more significant increase in (RON) and (MON) than MTBE for the same blending ratio. The Density of the mixtures also increases because both additives have a higher density than the fuel due to the presence of different hydrocarbon compounds. The mixture's distillation curves are distorted, especially when the low to the middle percent of blenders are added to fuels. However, higher percentages of additives show lower distillation temperatures.

Sequential isolation of metabolites and lipids from a single sample to achieve multiomics by using TRIzol reagent

Simultaneous extraction of various types of biomolecule from a single sample can be beneficial for multiomics studies of unique specimens. An efficient and convenient sample preparation approach must be developed that can comprehensively isolate and extract biomolecules from one sample. TRIzol reagent is widely used in biological studies for DNA, RNA, and protein isolation. This study evaluated the feasibility of using TRIzol reagent for the simultaneous isolation of not only DNA, RNA, and proteins but also metabolites and lipids from a single sample. Through the comparison of known metabolites and lipids obtained using the conventional methanol (MeOH) and methyl-tert-butyl ether (MTBE) extraction methods, we determined the presence of metabolites and lipids in the supernatant during TRIzol sequential isolation. Finally, we performed untargeted metabolomics and lipidomics to examine metabolite and lipid alterations associated with the jhp0417 mutation in Helicobacter pylori by using the TRIzol sequential isolation protocol and MeOH and MTBE extraction methods. Metabolites and lipids with significant differences isolated using the TRIzol sequential isolation protocol were consistent with those obtained using the conventional MeOH and MTBE extraction methods. These results indicated that TRIzol reagent can be used to simultaneously isolate metabolites and lipids from a single sample. Thus, TRIzol reagent can be used in biological and clinical research, especially in multiomics studies.

Evaluation of Spark Ignition Engine Performance and Operation Stability with Low Octane Gasoline and Methyl Tert-Butyl Ether Additive

Evaluation of Spark Ignition Engine Performance and Operation Stability with Low Octane Gasoline and Methyl Tert-Butyl Ether Additive

Low-pressure air plasma-assisted acrylic grafted polyetherimide ultrafiltration membranes with excellent oil-water separation and high anti-fouling performances

This paper reports the first surface modification of polyetherimide (PEI) ultrafiltration membranes using low-pressure air plasma-treated surfaces to induce acrylic acid (AA) graft polymerization, significantly improving their retention and fouling resistance properties. The successful formation of graft layers was verified by water contact angle (WCA) measurement of hydrophilic changes and Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis of the surface chemistry. Scanning electron microscopy (SEM) was used to analyze the morphological features, and atomic force microscopy (AFM) was tested for changes in surface roughness. The overall property changes after grafting were evaluated by mechanical tests and filtration tests. Methyl tert-butyl ether (MTBE) was chosen to measure the oil-water separability. The results showed that the membrane surface obtained PAA dense graft layer and improved hydrophilicity (CA from 57.62° to 29.26°) with no loss of tensile properties. In addition, the modified grafted membranes showed a high retention rate of BSA of 95.1 %, while the rejection rate of MTBE increased from 31.8 % to 75.9 %. Notably, PEI-g-AA fully recovered the permeability by simple water backwashing, exhibiting excellent antifouling performance. Therefore, this communication demonstrates that graft modification on the surface of PEI membranes is feasible and effective, and provides a new idea of PEI modification, which is valuable for exploring the development of high-efficiency ultrafiltration membranes.

Impact of oxygenated fuels on atmospheric emissions in major Colombian cities

The use of oxygenated gasolines has increased in Latin America over the past several years with the goal to reduce oil dependence, improve gasoline combustion and emit fewer pollutants to the atmosphere. Countries such as Brazil, Colombia, Mexico, Argentina, and Peru blend their gasoline with ethanol in different proportions. In Colombia, the regulation establishes a 10% vol of ethanol in gasoline (E10). Ethers are also used to oxygenate gasolines. MTBE (methyl tert-butyl ether) is blended in gasoline primarily in Mexico, Venezuela, and Chile, while ETBE (ethyl tertiary-butyl ether) is used in Argentina. The U.S. EPA Motor Vehicle Emissions Simulator (MOVES) model was adapted to Colombia to evaluate gasoline blends with two renewable oxygenates (ethanol and ETBE) on the emission of criteria pollutants (PM2.5, CO, NOx, SO2), Total Gaseous Hydrocarbons (TGH), Volatile Organic Compounds (VOCs), and toxic compounds. We followed the same approach used to build MOVES-Mexico and assess fuel specifications changes on vehicle emissions.The MOVES-Colombia model finds that E10 increases fuel volatility, VOCs, NOx, PM2.5, and SO2 emissions, and decreases CO relative to the unoxygenated base gasoline (E0). The impact of E10 consumption on air quality is due not only to primary pollutants, but also to the emission of ozone and PM2.5 precursors. Compared to E10 and E0, the ETBE blends reduce fuel volatility and emissions of VOCs, TGH, CO, NOx, PM2.5, and SO2. The introduction of ETBE could help major urban areas to meet air quality standards even with their current vehicle fleets. This work highlights that the effect of new fuel specifications needs to be properly assessed in terms of air quality before they are put in place. The development of modeling tools, such as MOVES-Colombia, facilitates the study of fuel quality and vehicle technology on pollutant emissions.

Characterization of protein concentrates obtained by defatting cricket, locust, and silkworm powders using one-step organic solvent extraction

Nutritional and functional properties were determined on proteins recovered from cricket, locust, and silkworm using a one-step organic solvent (OS) lipid extraction process. Hexane (H), chloroform (C), methyl-tert-butyl ether (MTBE), hexane:isopropanol (HI, 3.2, vol:vol) and chloroform:methanol (CM, 2:1, vol:vol) was used as the extraction solvents. Proximate composition, SDS-page, amino acid (AA) profile, and solubility were measured on the defatted insect powders. H and MTBE was the most effective OS tested, with the greatest concentration of protein and least lipid (p < 0.05) in the defatted insect powders. SDS-Page revealed a variety of proteins in each of the samples. The AA concentrations were increased in all H and MTBE samples. Defatted insect powders were most soluble between pH 11 and pH 12 when MTBE or H was used as the OS. Results show H or MTBE has the potential to extract lipids and concentrate protein from insect powders. Practical applicationProtein concentrates were developed by defatting insect powders (cricket, locust, silkworm) with a one-step extraction process that tested different organic solvents (OS). The resulting protein concentrates contained on average 75% protein and amino acid concentrations were increased. Results showed that of the OS tested, hexane or methyl-tert-butyl ether were most effective at removing lipids and concentrating protein from insect powders.

LC-MS/MS bioanalytical method for the quantitative analysis of nifedipine, bisoprolol, and captopril in human plasma: Application to pharmacokinetic studies.

In this study, the development and validation of an accurate and highly sensitive LC-MS/MS method were performed for the estimation of nifedipine, bisoprolol and captopril in real human plasma. Liquid-liquid extraction using tert-butyl methyl ether was efficiently applied for extraction of the analytes from plasma samples. The chromatographic separation was carried out using an isocratic elution mode on the X-terra MS C18 column (4.6 × 50 mm, 3.5μm). The mobile phase consisted of methanol-0.1% formic acid (95:5, v/v) for determination of nifedipine and bisoprolol and acetonitrile-0.1% formic acid (70:30, v/v) for determination of captopril with a flow rate of 0.5ml/min. Acceptable results regarding the different validation characteristics of the analytes were obtained in accordance with US Food and Drug Administration recommendations for bioanalytical methods. The developed approach was linear over concentration ranges of 0.5-130.0, 50.0-4,500.0 and 0.3-30.0ng/ml for nifedipine, captopril and bisoprolol, respectively. The method revealed a sufficient lower limit of quantification in the range of 0.3-50.0ng/ml, as well as high recovery percentages, indicating high bioanalytical applicability. The proposed method was efficiently applied to a pharmacokinetic evaluation of a fixed-dose combination of the analytes in healthy male volunteers.

ПЕРЕПРОФИЛИРОВАНИЕ УСТАНОВКИ ПО ПРОИЗВОДСТВУ МЕТИЛ-ТРЕТ-БУТИЛОВОГО ЭФИРА

The paper considers the possibility of repurposing a plant for the production of methyl tert-butyl ether (MTBE) for the esterification of a light fraction of gasoline by catalytic cracking. The conversion of the MTBE installation to the process of esterification of the light fraction of catalytic cracking gasoline will allow obtaining an additional amount of high-octane component for automotive gasoline

О ПОВЫШЕНИИ ЭФФЕКТИВНОСТИ УСТАНОВКИ ПО ПРОИЗВОДСТВУ МЕТИЛ-ТРЕТ-БУТИЛОВОГО ЭФИРА

The paper discusses measures to improve the efficiency of the plant for the production of methyl tert-butyl ether at JSC "Angarsk Petrochemical Company"

Improved energy recovery from the condensed steam as part of HEN retrofit

The conventional approach to heat exchanger network (HEN) retrofit involving design techniques based on Pinch Technology (PT) is extended to include minimization of energy losses resulting from steam-condensate expansion. The authors proposed a new approach to minimize energy losses in utility system, thermally coupled with the combined heat and power (CHP) plant, using condensate subcooling phenomena. Moreover, applying condensate subcooling can counteract the drawbacks of commonly used multi-stage condensate expansion which increase operability and reduces investment and maintenance costs. A case study illustrates the suitability of improved condensate management as a HEN retrofit measure. The study object is a Methyl-Tert-Butyl Ether (MTBE) plant processing 18 t/h isobutylene and consuming 4386 kW of hot utility (steam) in the HEN. A study of the maximum possible heat recovery using PT indicates that the combined heat recovery from hot process streams and condensate can be increased by 510 kW compared to the existing state. At the same time, it is possible to generate additional power of 120 kW in the CHP plant that supplies energy to the MTBE plant. The locations of heat exchangers are accounted for in HEN reconfiguring. A new scheme of steam and condensate system is presented.

Effect of time on alternative hydrocarbon production from waste PS with biodiesel of candlenut oil using catalytic cracking and Si/Al-Ceramic as catalyst

In the present study, the catalytic cracking process of polystyrene (PS) plastic waste and biodiesel of candlenut oil was carried out using Si/Al-ceramic catalyst with a mass ratio of 7:3 at 300 °C. This study aimed to investigate the effect of reaction time on the distribution of hydrocarbon fuel fractions produced. They are characterized by XRD, SEM-EDX, FTIR, and N2 gas adsorption-desorption. The products components of PS catalytic cracking were analyzed by gas chromatography-mass spectroscopy (GC-MS). The liquid fuel obtained was mixed with commercial fuel, Premium RON 88, and methyl tertiary butyl ether (MTBE) additive to determine its physicochemical properties and performance in a generator engine with gasoline-based fuel. The result showed that an increase in reaction time from 60 minutes to 120 minutes of PS cracking over Si/Al-Ceramic catalyst leads to the enrichment of long-chain hydrocarbon fraction (&gt; C12) by 25.61% which is attributed to the formation of styrene dimer. The fuel has thermal efficiency of 26.49% with density of 0.7405 g/cm3, flashpoint of &lt; -50 °C, calorific value of 9642.42 kcal/kg, and octane number of 92.2. These characteristics are in accordance with SNI 06-3506-1994 standard. Therefore, liquid fuel from catalytic cracking of polystyrene plastic wastes can be used as a potential alternative fuel in the gasoline range.

Changes in geotechnical properties of soil contaminated by methyl tertiary butyl ether (MTBE)

As an extensively used gasoline additive, methyl tertiary butyl ether (MTBE) can leak into the subsurface, and this not only damages the ecological environment but also affects the geotechnical characteristics of the soil. In this study, the geotechnical properties of MTBE-contaminated soil, such as the basic physical properties of strength, compressibility, hydraulic conductivity, leachability, electrical resistivity and microstructural characteristics, are comprehensively investigated. The results show that the Atterberg limits consistently decrease with increasing MTBE content in the soil. As the MTBE content increases from 0 to 10%, the specific surface area of the soil decreases by 28%, the sand content increases by 22%, and the clay and silt contents decrease by 3 and 18%, respectively. The soil compression index, hydraulic conductivity, leached MTBE concentration and electrical resistivity increase, while the unconfined compressive strength (UCS) decreases, with increasing MTBE content. Microstructural analysis shows that increasing the MTBE content results in mineralogical alterations that decrease the illite and kaolinite content of the soil. The aggregation and flocculated structures can be detected by an increase in the number and size of inter-aggregate pores. In addition, the electrical resistivity of the contaminated soil is used to assess the geotechnical properties of the MTBE-contaminated soil based on well-established empirical relations.

Anhydrous Ethanol Pricing in Economies with an Underdeveloped Biofuels Market: The Case of Mexico

Most gasoline currently consumed in Mexico continues to be oxygenated with Methyl Tert-Butyl Ether (MTBE) despite its proven effects on the environment and human health. Hence, the existence of a regulatory framework on biofuels and various institutional efforts have not been sufficient to develop a national market for anhydrous ethanol use as biofuel. The goal of this research is twofold: one, to review and analyze the governmental actions taken to incorporate bioethanol as a gasoline oxygenate, and, two, to design a tool to estimate the bioethanol price at the Storage and Distribution Terminals of PEMEX (Mexico’s state-owned oil company). A price estimation model for bioethanol was developed through the microeconomic theory of the producer and the indifference price of a product methodology, which calculates the daily price of ethanol in the period 2015–2022; additionally, an MS Excel-based support tool was created for this analysis (namely: the Price-CEM). The analysis showed that incorporating bioethanol into the Mexican energy matrix would require policies of fiscal support for R&amp;D, agricultural waste management and bioethanol production, as well as a new regulatory framework to both gradually eliminate MTBE and establish bioethanol/gasoline blending targets. Furthermore, institutional efforts would also be required to integrate all links in the biofuel production chain, including primary feedstock producers. The cost estimation method and tool have also shown to be valuable instruments to calculate both the prices at which a local bioethanol market would be competitive (with respect to the international market) and the most important cost contributions for local supply chains. This is the first tool to estimate the price of anhydrous ethanol at the local level, which can contribute to identifying opportunities and economic thresholds for the successful development of feasible bioethanol markets in Mexico.

A validated HPLC-MS/MS method for simultaneously analyzing curcumin, demethoxycurcumin, bisdemethoxycurcumin, tetra-hydrocurcumin and piperine in human plasma, urine or feces

BackgroundThe spice curcumin is supposed to have many different beneficial health effects. To understand the complete pharmacokinetics of curcumin we need an analytical method to determine curcumin and its metabolites in human plasma, urine or feces. We have developed an HPLC-MS/MS method for the simultaneous analysis of curcumin, demethoxycurcumin, bisdemethoxycurcumin, tetrahydrocurcumin and piperine in human plasma, urine or feces. MethodsSample pretreatment involved a simple liquid-liquid extraction with tert-butyl methyl ether. Conjugated curcumin and analogs can be measured after enzymatic hydrolysis. Reversed-phase chromatography with a linear gradient of 50–95% methanol in 0.1% formic acid was used. Total run time is 15 min. The method was validated with regards to stability, specificity, sensitivity, linearity, accuracy, repeatability and reproducibility. The applicability of the method was tested using actual patients samples. ResultsThe LLOQ in plasma, urine and feces for curcumin, demethoxycurcumin, bisdemethoxycurcumin, tetrahydrocurcumin and piperine ranged from 1 to 5 nM. Whereas all compounds could be quantified on a linear range between 2 and 400 nM. Plasma and feces recovery of curcumin was 97.1 ± 3.7% and 99.4 ± 16.2%, whereas urine showed a recovery of 57.1 ± 9.3%. All compounds had acceptable in-between day or between day variability in the different matrixes. ConclusionA HPLC-MS/MS method was developed and validated for the simultaneous quantification of curcumin, demethoxycurcumin, bisdemethoxycurcumin, tetrahydrocurcumin and piperine in human plasma, urine or feces. This method will aid in critically verifying the pharmacokinetics of curcumin made by supplement manufacturers and help us to provide insight in the claimed bioavailability of curcumin supplements.