Formic Acid Concentration Research Articles

Magnetic/Zeolitic Imidazolate Framework-67 Nanocomposite for Magnetic Solid-Phase Extraction of Five Flavonoid Components from Chinese Herb Dicranopteris pedata.

A magnetically functionalized Fe3O4@ZIF-67 metal-organic framework (MOF) was prepared by electrostatic self-assembly using magnetic Fe3O4 nanoparticles as the core and ZIF-67 as the shell. The composite was characterized by electron microscopy, X-ray diffraction, Fourier- transform infrared spectroscopy, and Brunauer-Emmett-Teller measurements. Magnetic solid-phase extraction (MSPE) was performed on five flavonoids from Dicranopteris pedata using Fe3O4@ZIF-67 as an adsorbent. The developed MSPE method was combined with high-performance liquid chromatography-ultraviolet detection to preconcentrate and separate five flavonoids (rutin, quercitrin, kaempferol-3-O-α-L-rhamnoside, quercetin, and kaempferol) from Dicranopteris pedata. The factors affecting the extraction, such as the amount of Fe3O4@ZIF-67 adsorbent, salt ion concentration in the sample solution, vortex time, type and amount of desorbing solvent, concentration of formic acid to acidify the desorbing solvent, and acetonitrile ratio, were optimized. The developed method showed good linearity over the concentration range of 1.09-70.0 μg∙mL-1 for the five flavonoids, with R2 values between 0.9901 and 0.9945. The limits of detection and average recoveries for the five flavonoids were in the ranges of 39.5-56.2 ng∙mL-1 and 92.2-100.7%, respectively. The method presented herein is simple, efficient, and sensitive; it can be used for enrichment analysis of the five flavonoids in Dicranopteris pedata.

SIMULTANEOUS DETERMINATION OF CHLOROGENIC ACIDS AND CAFFEINE BY REVERSED-PHASE HPLC

A variant of simultaneous determination of chlorogenic (monocaffeoylquinic and dicaffeoylquinic) acids and caffeine in coffee (drink) using reversed-phase chromatography with spectrophotometric detection has been developed. For separation, a gradient mode is proposed exploring of two components of the mobile phase containing 3 vol.% of formic acid and 6 and 20 vol.% acetonitrile in distilled water and chromatographic column 150×4.6 mm Symmetry C18, 3.5 μm. Column thermostat temperature is 30 °C. The choice of the type and concentration of the acidifier of the mobile phase is justified in the work. It has been established that the acidity of the mobile phases should not be lower than pH 2 in order to transfer most of the chlorogenic acids to the non-ionized state. The dependences of the retention of monocaffeoylquinic acids and caffeine on the concentration of acetonitrile and formic acid, which is more effective in the selectivity of separation compared to orthophosphoric acid in the mobile phase, are determined. The selectivity of the separation of these compounds depends more on the concentration of formic acid than on the concentration of acetonitrile. Concentrations of chlorogenic acids and caffeine were determined in drinks from two varieties of coffee, coffee husk (dried pericarp of coffee fruits) (produced in Vietnam) and for comparison of two more variants – Arabica coffee from roasted grains and from green decaffeinated grains from other manufacturers. It is shown that coffee husk is a valuable raw material for the preparation of an alternative drink. Thus, when using 1 g of coffee husk when brewing 100 ml of boiling water, a drink containing about 10 mg (per 100 ml) of monocaffeoylquinic acids, about 6 mg of dicaffeoylquinic acids and about 3 mg of caffeine was obtained. For citation: Blinova I.P., Oleinits E.Yu., Salasina Ya.Yu., Deineka V.I., Vu Thi Ngoc Anh, Nguyen Van Anh Simultaneous determination of chlorogenic acids and caffeine by reversed-phase HPLC. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 2. P. 45-52. DOI: 10.6060/ivkkt.20236602.6711.

A stationary phase with a positively charged surface allows for minimizing formic acid concentration in the mobile phase, enhancing electrospray ionization in LC-MS proteomic experiments.

The default choice of mobile phase acidifier for bottom-up LC-MS proteomic analyses is 0.10% formic acid because of its decent acidity, decent ion pairing ability, and low suppression of electrospray ionization. In recent years, state-of-the-art columns have been designed specifically to provide efficient separation even when using an MS-friendly mobile phase of low ionic strength. Despite this, no attempts have been made to improve the sensitivity of the MS-based analytical methods by reducing the amount of formic acid in the mobile phase. In this study, we evaluated the effect of reduced formic acid concentration in the mobile phase on the chromatographic behavior and MS response of peptides when separated using columns packed with a C18 stationary phase with a positively charged surface. Using 0.01% formic acid in the mobile phase maintained excellent chromatographic performance and increased MS signal response compared to the standard of 0.10%. The enhanced MS response translated to about 50% improved peptide identifications depending on the complexity and amount of sample injected. The increased retention of peptides at a reduced formic acid concentration was directly proportional to the number of acidic residues in the peptide sequence. The study was carried out by covering a spectrum of protein samples with varied complexity using analytical flow, micro-, and nanoflow regimes to expand the applicability in routine practice.

Technical versus biological variability in a synthetic human gut community

ABSTRACT Synthetic communities grown in well-controlled conditions are an important tool to decipher the mechanisms driving community dynamics. However, replicate time series of synthetic human gut communities in chemostats are rare, and it is thus still an open question to what extent stochasticity impacts gut community dynamics. Here, we address this question with a synthetic human gut bacterial community using an automated fermentation system that allows for a larger number of biological replicates. We collected six biological replicates for a community initially consisting of five common gut bacterial species that fill different metabolic niches. After an initial 12 hours in batch mode, we switched to chemostat mode and observed the community to stabilize after 2–3 days. Community profiling with 16S rRNA resulted in high variability across replicate vessels and high technical variability, while the variability across replicates was significantly lower for flow cytometric data. Both techniques agree on the decrease in the abundance of Bacteroides thetaiotaomicron, accompanied by an initial increase in Blautia hydrogenotrophica. These changes occurred together with reproducible metabolic shifts, namely a fast depletion of glucose and trehalose concentration in batch followed by a decrease in formic acid and pyruvic acid concentrations within the first 12 hours after the switch to chemostat mode. In conclusion, the observed variability in the synthetic bacterial human gut community, as assessed with 16S rRNA gene sequencing, is largely due to technical variability. The low variability seen in HPLC and flow cytometry data suggests a highly deterministic system.

Effects of Feeding Different Levels of Sprouted Barley on Fermentation Characteristics, Bacterial Quantification, and Rumen Morphology of Growing Lambs.

The objective of the present study was to investigate the effects of sprouted barley inclusion level on the growth performance, digestibility, volatile fatty acids, bacterial quantification, and rumen morphology of growing lambs. Five dietary treatments with sprouted barley (0, 25, 50, 75 and 100%) and nine replicates per dietary treatment were performed on forty-five Awassi lambs (90 days old). The average weight gain, intake, and digestibility of dry and organic matter were recorded. The pH, color, volatile fatty acids, bacterial quantification, and rumen histomorphometry were also determined. The results showed that the average dry and organic matter intake in T2 to T4 and the average weight gain in T4 decreased linearly. In contrast, the digestibility of dry and organic matter by sprouted barley (T2 to T4) was higher. The pH values and rumen color were not affected. Concentrations of formic acid, acetic acid, butyric acid, and the ratio of acetic acid to propionic acid were increased, while lactic acid and total volatile fatty acids were lower in all levels of sprouted barley. In addition, lambs fed T4 had a higher quantification of Anaerovibrio Lipolytica, Butyrivibrio Fibrisolvens, and Streptococcus Bovis quantification. Selenomonas Ruminantium was higher in T1, T2, and T4, whereas Megashpaera Elsdenii was lower in T1 to T3. The rumen histomorphometric was improved by sprouted barley (T2 and T3). Sprouted barley improved digestibility and rumen histomorphometry and increased the concentration of some volatile fatty acids and rumen bacteria but resulted in a decrease in average dry and organic matter intake, which negatively affected weight gain in lambs fed 100 % sprouted barley. Further studies are required to determine the potential effects on growing lambs fed sprouted barley.

One-Pot direct reductive amination of furfural over Pd@CNTs

N-substituted furfuryl amines (secondary amines) are important class of organic compounds which are primarily used in making agricultural and pharmaceutical intermediates. The main objective of the present study is to develop the use of bio-based ennvironment friendly chemical such as furfural for selective one-step process for N-substituted furfuryl amines production using formic acid (FA) as a hydrogen source over heterogeneous catalyst. Rh-CNTs, Pd-CNTs, Pd-Al2O3, and Pd-HT catalysts were prepared using a facile combination of wet impregnation, followed by freeze-drying method and used for the synthesis of N-substituted furfuryl amines. The as-synthesized and used catalysts were characterized by various physico-chemical characterization methods to investigate the role of support in promoting activity and selectivity of catalyst. Under optimised condition, Pd-CNTs catalyst in methanol was found to convert furfural and aniline almost completely to N-(furan-2-ylmethyl)aniline. Moreover, Pd-CNTs catalyst showed outstanding activity towards complete decomposition of FA to H2 and CO2, giving a high yield of N-(furan-2-ylmethyl)aniline (>99%) from hydrogenation of furfural and aniline. The catalyst also showed good recyclability and worked for at least three consecutive recycling runs without lossing activity. The effect of reaction parameters viz. temperature, reaction time, and FA concentration, on the conversion and selecivity were studied in detail.

The SMYD3-MTHFD1L-formate metabolic regulatory axis mediates mitophagy to inhibit M1 polarization in macrophages.

SMYD3 (protein 3 containing SET and MYND structural domains) belongs to the SMYD methylesterase family and is a histone lysine methyltransferase that promotes gene transcription mainly by catalysing the trimethylation of lysine at position 4 of histone subunit 3 (H3K4me3). Studies have shown that SMYD3 plays a key role in tumour cell proliferation and differentiation; however, its role in macrophage polarization is unclear. We screened the M1- and M2-polarized macrophage differential histone modifying enzyme using bioinformatics analysis. The SMYD3 overexpression plasmid was transfected into M1 macrophages, and the SMYD3-regulated target gene was analysed by RNA-seq and ChIP-Seq. The effect of knocking down MTHFD1L on M1 polarization and the change of the intracellular metabolite formic acid content were investigated. M1 macrophages were stimulated with different concentrations of formic acid (2, 10 and 40mM) to detect the expression of M1-related genes, ROS production, and changes in the expression of the mitophagy-related proteins LC3, PINK1 and p-Parkin. Here, we used bioinformatics to analyse SMYD3, a histone methyltransferase associated with M1 polarization; overexpression of SMYD3 significantly suppressed the LPS/IFN-γ-induced M1 phenotype in macrophages. RNA-seq analysis demonstrated that SMYD3 significantly activated the one-carbon folate metabolic pathway in M1 macrophages. In addition, we used ChIP-seq analysis to identify methylenetetrahydrofolate dehydrogenase 1-like (MTHFD1L) as the target gene of the transcriptional activation by SMYD3 through H3K4me3 histone modification. Activation of MTHFD1L causes the accumulation of the intracellular metabolite formate. Exogenous stimulation with different concentrations of formate increased the expression of key genes involved in the mitochondrial respiratory chain complex, ROS production, and the expression of autophagy-related proteins LC3, PINK1, and p-Parkin and suppressed the expression of M1-related genes. Our study demonstrates that SMYD3 regulates the activity of the mitochondrial metabolic enzyme MTHFD1L through H3K4me3 histone methylation modification, promotes formate synthesis and induces mitophagy, which inhibits M1 polarization in macrophages.

Comparative analysis of the effects of hydrogen and formic acid on the vacuum residue hydrocracking

The improvement of the existing technologies aimed at deeper processing of heavy oils and oil residues and development of new ones is an urgent task of modern oil refining. Experiments in a flow installation using a quartz reactor were performed to determine the formic acid decomposition pathway. The experiments showed that the formic acid decomposition over the Ni-Mo/Al2O3 catalyst predominantly yielded hydrogen and CO2. Therefore, in this study comparative experiments on the effects of hydrogen and formic acid on the vacuum residue hydrocracking in the presence of the Ni-Mo/Y-Al2O3 and Ni-Mo/Al2O3 catalysts were performed at 375–400 °C and 0.45 MPa pressure. The concentration of hydrogen or formic acid in argon was 10 vol%. The catalysts were prepared by impregnation of the corresponding supports with the aqueous solution obtained using nickel hydroxide, ammonium heptamolybdate and citric acid. Electron microscopy and XRD studies of the Ni-Mo/Y-Al2O3 and Ni-Mo/Al2O3 catalysts demonstrated that the active component in the studied catalysts was in a finely dispersed state. The size of Ni-Mo particles was 0.4–0.6 nm in the Ni-Mo/Y-Al2O3 catalyst and 0.3–0.6 nm in Ni-Mo/Al2O3. For both catalysts Ni-Mo/Y-Al2O3 and Ni-Mo/Al2O3 higher vacuum residue conversion to liquid products was observed in the presence of formic acid than in the presence of hydrogen. Hydrogen substitution for formic acid vapor during the vacuum residue hydrocracking also results in the lower sulfur content in the liquid reaction products. The use of formic acid as a hydrogen donor significantly simplifies the process hydrocracking.

Electrochemical conversion of CO2 to formic acid using a Sn based cathode: Combined effect of temperature and pressure

Electrochemical conversion of CO2 in the aqueous electrolyte into value-added chemicals is considered one of the most promising strategies to valorize waste-CO2. In the last decade, high attention was focused on the electrochemical synthesis of formic acid (FA) via CO2 reduction using Sn cathodes. To improve the final concentration of FA in aqueous electrolytes, several approaches, including the utilization of different technologies (i.e. pressurized CO2 reactor, a gas diffusion electrode, divided cell etc…) and different operative conditions (i.e. pH, current densities, temperature, mixing rate, etc...) were investigated in detail. To date, the effect of temperature (T) on the electrochemical conversion of CO2 into FA under pressurized undivided cells is still unexplored. Hence, in this work, the simultaneous effect of CO2 pressure (PCO2) (1 ÷ 3 bar) and T (3 ÷ 60 °C) on the electrochemical synthesis of FA in an aqueous electrolyte using a Sn cathode was studied in detail. It was found that the adoption of low T and high PCO2 values allows to work at high current densities (j) by achieving high final concentrations of FA ([FA]) and good relative faradaic efficiency (FEFA). As an example, a quite high final [FA] of approximately 360 mM coupled with a FEFA higher than 50% was reached in an aqueous electrolyte by working at T of 10 °C, j of − 75 mA cm−2 and PCO2 of 30 bar.

Low CO2 hydrogen streams production from formic acid through control of the reaction pH

There are multiple factors that influence the catalyst performance in the reaction of formic acid dehydrogenation: the nature of catalyst and/or support, the used solvent and reaction variables such as temperature, time, formic acid concentration, presence/absence of formates and pH of the solution. This work evaluates a series of important parameters like the influence of the pH by itself, the influence of the nature of used alkali agents and the effect of direct formate addition as reactive on hydrogen production via formic acid dehydrogenation over a commercially available catalyst. The catalytic performance appears to depend on the ionic radius of the cations of the used base which reflects consequently on the hydrogen selectivity. The best base to be used must have lower hydrated cationic radii and a starting pH around 4 to achieve important hydrogen selectivity for medium term formic acid conversion.

Decomposition of Formic Acid and Acetic Acid into Hydrogen Using Graphitic Carbon Nitride Supported Single Metal Catalyst

In a combination of generation and storage of hydrogen gas, both formic acid (FA) and acetic acid (AA) have been notified as efficient hydrogen carriers. This study was conducted to synthesize the monometallic catalysts namely palladium (Pd), copper (Cu), and zinc (Zn) on graphitic-carbon nitride (g-C3N4) and to study the potential of these catalysts in FA and mixed formic acid (FA)-acetic acid (AA) decomposition reaction. Several parameters have been studied in this work such as the type of active metals, temperature, and metal loadings. The mass percentage of Pd, Cu, and Zn metal used in this experiment are 1, 3, and 5 wt%, respectively. At low temperature of 30 °C, 5 wt% Pd/g-C3N4 catalyst yielded higher volume of gas with 3.3 mL, instead of other Pd percentage loadings. However, at higher temperature of 70 °C and 98% FA concentration, Pd with 1 wt%, 3 wt%, and 5 wt% of loading over g-C3N4 has successfully produced optimum gas (H2 and CO2) of 4.3 mL, 7.4 mL, and 4.5 mL in each reaction, respectively. At higher temperature, Pd metal showed high catalytic performance and the most active element of monometallic system in ambient condition. Meanwhile, at higher percentage of Pd metal, the catalytic decomposition reaction also increased thus producing more gas. However, it can be seen the agglomeration of the particles formed at higher loadings of Pd (5 wt%), and remarkably lowering the catalytic activity at higher temperature, while higher activity at low temperature of 30 °C. The result also showed low catalytic decomposition reaction for Cu and Zn catalyst, due to the small formation of Cu and Zn metal, but presence of high metal oxide (CuO) and (ZnO) promotes the passive layer formation on the catalyst surface.

Transcriptome Profiling Analysis of Phosphate-Solubilizing Mechanism of Pseudomonas Strain W134.

Phosphate-solubilizing bacteria (PSB) can alleviate available phosphorus deficiency without causing environmental pollution, unlike chemical phosphate fertilizers. However, the phosphate solubilization mechanisms of PSB are still unclear. Transcriptome sequencing was used to analyze the expression patterns of differential expressed genes (DEGs) of the phosphate-solubilizing bacterium W134 under the conditions of soluble phosphorus (group A), insoluble phosphorus (group B), and lacking phosphorus (group C). Nine DEGs in three different groups were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Then, high performance liquid chromatography (HPLC) was applied to detect the concentrations and composition of organic acids. Compared with group A, Gene Ontology (GO) annotation showed that the cluster of W134 DEGs in groups B and C were basically the same. Besides, the results of enrichment Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway indicated that genes in the Citrate cycle (TCA cycle) pathway closely related to organic acid production were significantly upregulated. The qRT-PCR results were almost consistent with the expression trends of the transcriptome data. The HPLC results showed that the formic acid, ascorbic acid, acetic acid, citric acid, and succinic acid concentrations were significantly increased in group B and C (p < 0.05), while the contents of lactic acid and malic acid were significantly increased in group B (p < 0.05). The above results provided further validation that the upregulated genes should be related to W134 secretion of organic acids. Our study revealed several potential candidate genes and tried to explain phosphate solubilization mechanisms. This provides a new insight for calcareous reclaimed soil, and it will reduce the need of chemical phosphate fertilizers to promote environmentally friendly agriculture.

Effect of Formic and Acetic Acids on Corrosion of 410 Stainless Steel in Bio-Oils

Biomass derived oils, made from decomposition and conversion of biomass feedstocks, are proposed as alternative sustainable fuels and potential precursors to valuable chemicals. Bio-oils are produced using different approaches including hydrothermal liquefaction and fast pyrolysis of biomass feedstocks. The composition of bio-oils varies depending on the biomass source as well as on the production method. Bio-oils also contain various functional groups including carboxyl, ketone, aldehyde, phenol etc. Among the functional groups, compounds containing oxygenated species such as carboxyl, phenol and ketone groups can be particularly corrosive to metallic and polymeric materials used for transportation, production, and storage of bio-oils. Formic and acetic acids are some of the most prevalent carboxylic acids present in fast-pyrolysis bio-oils and pose a concern for corrosion of metal alloys. In the present study, we varied the amounts of carboxylic acids in a forest residue fast pyrolysis bio-oil to assess their effects on corrosion of type 410 stainless steel (410SS). To study the effect of formic and acetic acids on corrosion in bio-oils, we exposed 410SS specimens in FR3 (forest residue, fast pyrolysis bio-oil) in short term (48 hour), mild temperature (50 °C) exposures. 410SS specimens were polished, weighed and exposed to fast pyrolysis bio-oil (FR3) with baseline modified total acid number (AMTAN) value of 50.1 mg of KOH per gram of bio-oil. Using a piece of Teflon string, specimens were suspended in approximately 25 g of bio-oil at 50 °C for 48 hours. The oil samples were then spiked with either formic or acetic acids. Capillary electrophoresis was used to quantify formic and acetic acids present in the bio-oil. The area under the curves were determined and correlated to concentration of each specie using standards. Electrochemical Impedance Spectroscopy (EIS) was also performed to investigate corrosion behavior of 410SS in FR3 bio-oil at room temperature. A miniature glass cell & Luggin capillary to minimize ohmic drop within the bio-oil phase was utilized. Reference mercury sulfate electrode and platinum mesh counter electrode were used for EIS measurements.The results of short-term (48 hour, 50°C) exposures of 410SS coupons in bio-oils with addition of small carboxylic acids are shown in Figure 1. Mass change plot vs the concentration of formic acid is shown in the left graph. We observed linear increase in mass loss of 410SS with increasing formic acid concentration in the bio-oil. This is expected given our previous results that showed corrosivity of formic acid towards low chromium alloys. Iron formate was the main corrosion product that formed on the surface. However, acetic acid shows the opposite effect on mass change data as shown in the graph on the right in Figure 1. Increasing addition of acetic acid resulted in decreased mass loss. This result is intriguing because acetic acid unexpectedly behaves as a corrosion inhibitor. We are currently performing more experiments to study this effect and to understand the reason for seemingly inhibitory effect of acetic acid on corrosion of 410 stainless steel. Mass changes and cross-sectional examination of post-exposure SS410 specimens, using scanning electron microscopy equipped with energy dispersive x-ray spectroscopy, will also be presented. Impedance data from EIS measurements were analyzed as another means to assess corrosion performance of SS410 in the bio-oil and used for comprehensive corrosion assessment along with other results. Funding provided by DOE Bioenergy Technologies Office. Figure 1

Electrochemical Reduction of Flue Gas CO2 in a Dual Methanol/Water Electrolysis System for the Synthesis of Methyl Formate

The conversion of waste CO2 to value-added chemicals through electrochemical reduction is a promising technology for mitigating climate change while simultaneously providing economic opportunities. The use of the nonaqueous solvent methanol allows for higher CO2 solubility and novel products through the incorporation of methanol as an intermediate. In this work, the electrochemistry of CO2 reduction in acidic methanol catholyte at a Pb working electrode was investigated while using a separate aqueous anolyte to promote a sustainable water oxidation half-reaction. The selectivity among methyl formate (a product unique to reduction of CO2 in methanol), formic acid, and formate was critically dependent on the catholyte pH, with a faradaic efficiency for methyl formate as high as 75% measured in pH < 2. Furthermore, strategies to limit the concentration of formic acid and maintain the surface oxide of the catalyst have been shown to be effective at improving the steady-state durability of the CO2-to-methyl formate process. Tests with simulated flue gas as the feedstock have shown a high level of tolerance for the Pb-catalyzed electrolysis to SO2, NO, and dilute O2 contaminants. Finally, a comparative technoeconomic analysis will be discussed to highlight target performance metrics and the viability of alternate pathways for electrochemical conversion of CO2 to methyl formate.

(Digital Presentation) Electrocatalytic CO2 Reduction to Formic Acid: Kinetics and Equilibrium Modeling for the Downstream Separation of Formic Acid with Anion Exchange Resins

Electrocatalytic carbon dioxide reduction reaction (CO2RR) technology can simultaneously minimize the CO2 concentration in the atmosphere and generate useful chemicals and fuels. Liquid formic acid (FA) produced from CO2RR is a chemical feedstock for industrial purposes as well as a potential hydrogen storage medium. The downstream separation of liquid FA from the CO2RR effluent increases the total costs in addition to the electrolysis and can also affect the environment adversely. Therefore, efficient, low-cost, and environmentally benign technologies for FA separation from the CO2RR are important for life cycle analysis and techno-economic analysis for this technology. Ion exchange has been proven as an advanced process for FA separation from aqueous solution. This method has attractive due to its high selectivity, low cost, ease of operation and recovery, availability to integrate with other systems, and environmentally benign nature.In this work, three anion exchange resins: Ambersep 900 hydroxide, Amberlite IRA-96 free base, and Amberlite IRA-910 chloride forms have been tested to separate FA from the aqueous solution under varying resin loading (10-60 mg/mL) and initial FA concentration (0.05-0.50 M). The effect of potassium bicarbonate, a commonly used catholyte in electrochemical CO2RR on equilibrium FA adsorption capacity has been investigated with resin loading of 10 and 60 mg/mL under similar initial FA concentrations.Kinetics and equilibrium studies data for the FA adsorption on three resins are interpreted using several kinetics and isotherm models. The kinetics data fits better with pseudo first order at high initial FA concentration and pseudo second order at low initial FA concentration. The results show that the Ambersep 900 hydroxide form with adsorption capacity of 430.8 mg of FA per g of resin is more efficient than the Amberlite IRA-96 free base form (369.9 mg/g) and Amberlite IRA-910 chloride form (291.2 mg/g) in the absence of potassium bicarbonate in the range of parameters studied. However, Amberlite IRA-96 (153.4 mg/g) and Amberlite IRA-910 (143.4 mg/g) can separate FA more efficiently from the potassium bicarbonate aqueous solution than the Ambersep 900 (94.1 mg/g). The experimental data for all resins can be well explained with the Freundlich isotherm model. In the presence of potassium bicarbonate, competitive adsorption of bicarbonate and formic acid reduces the FA adsorption capacity of resins. Experimental and modeling results will be discussed.

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

Highly Selective Photocatalytic Conversion of Glucose on Holo-Symmetrically Spherical Three-Dimensionally Ordered Macroporous Heterojunction Photonic Crystal

UHPLC-ESI-MS/MS assay for quantification of endocannabinoids in cerebrospinal fluid using surrogate calibrant and surrogate matrix approaches

Endocannabinoids are endogenous lipids with the main function recognized to act as neuromodulators through their cannabinoid receptors. Dysregulation of the endocannabinoid system is implicated in various pathologies, such as inflammatory and neurodegenerative diseases. In this study we describe a sensitive UHPLC-MS/MS method for the analysis of trace levels of 7 endocannabinoids in cerebrospinal fluid samples. The analytes covered comprised 1- and 2-arachidonoylglycerol 1- and 2-AG (which were analysed as sum due to their interconversion), 2-arachidonylglycerol ether 2-AGE, anandamide AEA, N-linoleoyl ethanolamide LEA, N-palmitoyl ethanolamide PEA and N-oleoyl ethanolamide OEA. Analytes were extracted from the biofluid by a simple monophasic procedure involving protein precipitation with acetonitrile (MeCN). The analytical method is based on chromatographic separation of the analytes with solid-core (core-shell, superficially porous) particle column Cortecs C18+ . Gradient elution with changing proportion of water and acetonitrile and constant concentration of formic acid provided reasonable separation of analytes, close elution of analytes and their internal standards and minimized matrix effects in biological samples. For specific detection of the endocannabinoids a triple-quadrupole tandem mass spectrometer with electrospray ionisation (ESI) and selected reaction monitoring (SRM) mode was used, and it provided good assay selectivity. The developed method required a minute volume of the biological samples (50 µL) and achieved excellent sensitivity (the lower limit of detection was between 4.15 and 30.18 pM of the biological sample). Linear calibration was achieved in the range from 25 to 10,545 pM for AEA, 90–3802 pM for 1-AG, 90–724 pM for 2-AG, 12–5226 pM for LEA, 33–13,942 for OEA, 34–23,850 pM for 2-AGE, 72–30,190 for PEA and 10–4218 for AEA-d4 in CSF. The method was validated and revealed relative errors in the range of − 14.7 to + 12.3% at LLOQ and − 14.1 to + 14.2% for the remaining validation range. Precisions were in the acceptable range (< 20% RSD at LLOQ, and <15% for the remaining levels) as well. It was finally used to quantify endocannabinoids in human cerebrospinal fluid obtained from 118 donors. Accurate quantification of endogenous compounds in biological samples was achieved by using two different principal approaches (surrogate matrix for AEA, 2-AG, OEA, 2-AGE, LEA and PEA, and surrogate calibrant for AEA only) and they were evaluated by use of the Passing-Bablok regression. Concentrations (median) of CSF samples of patients suffering from CNS infection and controls were found to be around 160 pM for 1- and 2-AG, 86 pM for AEA, 62 for 2-AGE, 58 for LEA, 93 pM for PEA, and 83 pM for OEA.

Rapid analysis of residual pinoxaden and its metabolites in wheat (Triticum aestivum L.) using the QuEChERS method with HPLC-MS/MS

Pinoxaden is a phenylpyrazolin herbicide that is used in grain fields to prevent gramineous weeds. This study developed a rapid method for the analysis of pinoxaden and its metabolite M4 in wheat using the QuEChERS method in combination with high-performance liquid chromatography with tandem mass spectrometry (HPLC- MS/MS). Pinoxaden was extracted from wheat into acetonitrile. For the extraction of M4, different concentrations of formic acid in acetonitrile were used (8% formic acid in acetonitrile for grain and 5% formic acid in acetonitrile for straw). To improve recovery of M4, water was added to the grain and straw to achieve moistness. For purification of the extract, the stationary phase was prepared using 50 mg of C 18 combined with 100 mg anhydrous MgSO 4 . By following a controlled trial, the average recoveries from wheat grain and straw ranged from 76% to 107% at four different concentration levels. Inter-day and intra-day relative standard deviations (RSDs) were lower than 8.7% for all analytes. The limits of detection (LODs) and limits of quantification (LOQs) ranged from 0.03 to 0.6 μg/kg and 0.1–2 μg/kg. Good linearities with determination coefficients higher than 0.9990 were obtained in the studied concentration ranges. Thereafter, wheat samples from 12 cities in China were examined and the results showed that the residues of pinoxaden and M4 in wheat were acceptable according to best practice. • QuEChERS method was used for extraction and cleanup pinoxaden and M4 in wheat instead of complex steps. • Different concentrations of formic acid in acetonitrile realized complete extraction of M4 in wheat. • The method was applied to detect residual pinoxaden and M4 in wheat samples. • The results showed that residues of pinoxaden and M4 were no significant in wheat in China.

"One-pot" preparation of aminated carbon nanotube-modified magnetic nanoparticles and their application to the quantification of phenoxyacetic acid herbicides in cereal and vegetable samples

有效萃取是分析复杂样品中苯氧羧酸类除草剂(PAs)残留的关键步骤。为此,该文利用“一锅法”水热技术快速、简便地制备了氨基碳纳米管功能化磁性纳米粒子(NH2-CNTs@M)并作为磁固相萃取(MSPE)的萃取介质,用于萃取谷物和蔬菜样品中痕量PAs。研究利用多种手段对NH2-CNTs@M的形貌、尺寸、磁性性质等进行了表征,结果表明Fe3O4的粒径、氨基化碳纳米管的直径以及NH2-CNTs@M的磁饱和值分别为30 nm、40 nm和44.2 emu/g。详细考察了制备条件和萃取参数对NH2-CNTs@M/MSPE萃取性能的影响,结果表明,NH2-CNTs@M/MSPE可通过π-π、疏水和氢键作用有效富集目标化合物,最佳萃取条件如下:吸附剂用量为30 mg,解吸溶剂为含2.0%(v/v)甲酸的乙腈溶液,吸附时间和解吸时间分别为8.0 min和3.0 min,基底pH值为6.0,不调节基底的离子强度。将NH2-CNTs@M/MSPE与高效液相色谱-二极管阵列检测技术(HPLC-DAD)联用,建立了谷物和蔬菜中PAs的灵敏检测方法。谷物和蔬菜基质中苯氧羧酸类除草剂的检出限(LOD, S/N=3)分别为0.32~1.6 μg/kg和0.53~1.6 μg/kg,定量限(LOQ, S/N=10)分别为0.94~4.8 μg/kg和1.6~4.8 μg/kg。在两种实际样品中不同浓度下的加标回收率分别为73.1%~112%和72.3%~113%。与现有方法相比,所建方法具有萃取速度快、灵敏度高和环境友好等特点。

Lower plasma concentrations of short-chain fatty acids (SCFAs) in patients with ADHD

Short-chain fatty acids (SCFAs), produced during bacterial fermentation, have been shown to be mediators in the microbiota-gut-brain axis. This axis has been proposed to influence psychiatric symptoms seen in attention deficit hyperactivity disorder (ADHD). However, there is no report of plasma SCFA concentrations in ADHD. The aim of this study was to explore the plasma concentrations of SCFAs in children and adults with ADHD and the possible factors that could influence those levels. We collected data on age group, sex, serum vitamin D levels, delivery mode, body mass index, diet, medication and blood samples from 233 ADHD patients and 36 family-related healthy controls. The concentrations of SCFAs and the intermediary metabolite succinic acid, were measured using liquid chromatography-mass spectrometry. Adults with ADHD had lower plasma concentrations of formic, acetic, propionic and succinic acid than their healthy family members. When adjusting for SCFA-influential factors among those with ADHD, children had lower concentrations of formic, propionic and isovaleric acid than adults, and those who had more antibiotic medications during the last 2 years had lower concentrations of formic, propionic and succinic acid. When adjusting for antibiotic medication, we found that among children, those currently on stimulant medication had lower acetic and propionic acid levels, and adults with ADHD had lower formic and propionic acid concentrations than adult healthy family members. In all, our findings show lower-than-normal plasma concentrations of SCFAs in ADHD explained in-part by antibiotic medication, age and stimulant medication. Whether or not this is of clinical significance is yet to be explored.