Chromatography-mass Spectrometry System Research Articles

A simple method for daily inspections of gas chromatography-mass spectrometry systems with an instrumental detection limit as an indicator

The purpose of this paper is to propose a simple method for daily inspections of a gas chromatography-mass spectrometry (GC–MS) system with an instrumental detection limit (IDL) as an indicator. A definition of DLs by ISO is 3.3σ where σ denotes the standard deviation (SD) of blank measurements. Estimation of σ is carried out according to the function of mutual information (FUMI) theory and actually with commercial software (TOCO19). An IDL which is a combination of a signal area, width and noise level is concluded to be a good indicator for daily inspections compared with each of its constituents. Methyl stearate is used as a standard material for the daily inspection of a programmed-temperature GC–MS system. A short chromatogram of 1800 data points (1.5 min) containing a target signal and background noise is fit for the IDL prediction by TOCO19. The relative SDs (RSDs) based on the theoretically estimated σ are shown to coincide with statistical results from repeated measurements within 95% confidence intervals. Column temperature is observed to affect IDLs through background fluctuation and then temperature-IDL relationship is examined in a range from 170 to 270 °C. Actual daily inspections over a month are demonstrated.

Identification of azaphilone derivatives of Monascus colorants from Talaromyces amestolkiae and their halochromic properties

Currently, the ability to produce several kinds of water-soluble red natural colorants makes the genus Talaromyces particularly important to the dye industry, which can be an alternative to the use of harmful synthetic colorants. In this study, colored compounds produced by Talaromyces amestolkiae were extracted, characterized chemically and the color stability of the fermented broth without any extraction procedure was further evaluated over pH variation. Five azaphilones compounds were detected by Ultrahigh Performance Liquid Chromatography-Mass Spectrometry system, all being complexes of the fatty acid amino-hexanedioic acid and azaphilone Monascus colorants. The color of the fermented broth was stable at a wide range of pH (3–9). Furthermore, T. amestolkiae colorants precipitated through hydrolysis of key chemical groups at extremely acidic (pH 1) and lose red color in extremely basic (pH 13) medium, showing negative halochromism. Nevertheless, these findings enhance the industrial relevance of azaphilone colorants produced by biotechnological process.

A Study on the Behavior Patterns of Liquid Aerosols Using Disinfectant Chloromethylisothiazolinone/Methylisothiazolinone Solution.

This study evaluates the behavioral characteristics of components (methylisothiazolinone (MIT) and chloromethylisothiazolinone (CMIT)) contained in disinfectant solutions when they convert to liquid aerosols. The analytical method for MIT and CMIT quantitation was established and optimized using sorbent tube/thermal desorber-gas chromatography-mass spectrometry system; their behavioral characteristics are discussed using the quantitative results of these aerosols under different liquid aerosol generation conditions. MIT and CMIT showed different behavioral characteristics depending on the aerosol mass concentration and sampling time (sampling volume). When the disinfectant solution was initially aerosolized, MIT and CMIT were primarily collected on glass filter (MIT = 91.8 ± 10.6% and CMIT = 90.6 ± 5.18%), although when the generation and filter sampling volumes of the aerosols increased to 30 L, the relative proportions collected on the filter decreased (MIT = 79.0 ± 12.0% and CMIT = 39.7 ± 8.35%). Although MIT and CMIT had relatively high vapor pressure, in liquid aerosolized state, they primarily accumulated on the filter and exhibited particulate behavior. Their relative proportions in the aerosol were different from those in disinfectant solution. In the aerosol with mass concentration of ≤5 mg m−3, the relative proportion deviations of MIT and CMIT were large; when the mass concentration of the aerosol increased, their relative proportions constantly converged at a lower level than those in the disinfectant solution. Hence, it can be concluded that the behavioral characteristics and relative proportions need to be considered to perform the quantitative analysis of the liquid aerosols and evaluate various toxic effects using the quantitative data.

LC-MS/MS Proteomic Study of MCF-7 Cell Treated with Dox and Dox-Loaded Calcium Carbonate Nanoparticles Revealed Changes in Proteins Related to Glycolysis, Actin Signalling, and Energy Metabolism.

Simple SummaryThis work revealed that DOX-Ar-CC-NPs have the ability to promote cell death in MCF-7 cells, showing high potency in drug delivery. DOX-Ar-CC-NPs prompts cell death of MCF-7 cancer cells in vivo. LC-MS/MS Proteomic experemnt showed alteration on the expression of proteins linked to actine signaling, carbohydrate metabolisim.One of the most prevalent death causes among women worldwide is breast cancer. This study aimed to characterise and differentiate the proteomics profiles of breast cancer cell lines treated with Doxorubicin (DOX) and Doxorubicin-CaCO3-nanoparticles (DOX-Ar-CC-NPs). This study determines the therapeutic potential of doxorubicin-loaded aragonite CaCO3 nanoparticles using a Liquid Chromatography/Mass Spectrometry analysis. In total, 334 proteins were expressed in DOX-Ar-CC-NPs treated cells, while DOX treatment expressed only 54 proteins. Out of the 334 proteins expressed in DOX-CC-NPs treated cells, only 36 proteins showed changes in abundance, while in DOX treated cells, only 7 out of 54 proteins were differentially expressed. Most of the 30 identified proteins that are differentially expressed in DOX-CC-NPs treated cells are key enzymes that have an important role in the metabolism of carbohydrates as well as energy, including: pyruvate kinase, ATP synthase, enolase, glyceraldehyde-3-phosphate dehydrogenase, mitochondrial ADP/ATP carrier, and trypsin. Other identified proteins are structural proteins which included; Keratin, α- and β-tubulin, actin, and actinin. Additionally, one of the heat shock proteins was identified, which is Hsp90; other proteins include Annexins and Human epididymis protein 4. While the proteins identified in DOX-treated cells were tubulin alpha-1B chain and a beta chain, actin cytoplasmic 1, annexin A2, IF rod domain-containing protein, and 78 kDa glucose-regulated protein. Bioinformatics analysis revealed the predicted canonical pathways linking the signalling of the actin cytoskeleton, ILK, VEGF, BAG2, integrin and paxillin, as well as glycolysis. This research indicates that proteomic analysis is an effective technique for proteins expression associated with chemotherapy drugs on cancer tumours; this method provides the opportunity to identify treatment targets for MCF-7 cancer cells, and a liquid chromatography-mass spectrometry (LC-MS/MS) system allowed the detection of a larger number of proteins than 2-DE gel analysis, as well as proteins with maximum pIs and high molecular weight.

CO2 huff-n-puff process to enhance heavy oil recovery and CO2 storage: An integration study

In this study, experimental and mathematical studies were carried out to investigate heavy oil production performance using the carbon dioxide (CO2) huff-n-puff process, as well as the potential of CO2 storage in abundant reservoirs. Five experiments were conducted under different injection pressures and different pressure depletion rates. The components in the produced heavy oil were measured using a gas chromatography-mass spectrometry system to investigate the influence of CO2 extraction under different injection pressures in different cycles. The experimental results indicate that (a) heavy oil recovery factor increases with increasing injection pressure. (b) CO2 extraction of the light/medium components in heavy oil affect heavy oil production. (c) With different pressure depletion rates, an optimized pressure depletion rate can be identified as 4 kPa/min. And (d) the relationship between heavy oil and gas production can be predicted using the developed equation with high agreements. Mathematically, the potential of CO2 storage and CO2 capacity were calculated, and the investigations show that the most significant influences on CO2 capacity are CO2 stored in the available space and dissolving into the remaining heavy oil. An objective function was developed to optimize the heavy oil recovery factor and the CO2 storage factor in the CO2 huff-n-puff process. The influences of weights between heavy oil production and CO2 storage were investigated, and the optimized case with the same weight (0.5) was studied.

Fatty Acid Composition of Rhodococcus aetherivorans Cells During Phenol Assimilation

The ability of microorganisms to survive in unfavorable conditions and maintain their biodegradation activity is mainly associated with changes in the composition of their cellular lipids. One of the factors of negative impact on cells can be their interaction with petroleum hydrocarbons, especially monoaromatic compounds, which are toxic to microorganisms even in small amounts. Aim. To research the changes in the cell fatty acids composition of Rhodococcus aetherivorans UCM Ac-602 strain during phenol degradation. Methods. The cultivation of the strain was carried out in a liquid mineral medium with initial phenol concentration 0.75, 1.0 and 1.5 g/L as a sole carbon and energy source. Cells grown in medium with n-hexadecane (7.5 g/L) and glucose (5.0 g/L) were used as controls. Fatty acid methyl esters were obtained by hydrolysis of cells in a 5% solution of acetyl chloride in methanol, followed by extraction with a mixture of ether-hexane. Identification of methyl esters was performed using a gas chromatography-mass spectrometry system Agilent 6800N/5973 inert (Agilent Technologies, US). The fatty acid content was determined using AgilentChemStation software. Results. Among the cellular fatty acids of R. aetherivorans UCM Ac-602 the straight-chain saturated hexadecanoic (C16:0), unsaturated hexadecenoic (C16:1 cis-9) and octadecenoic (C18:1 cis-9) acids as well as branched 10-methyl octadecanoic (tuberculostearic) (10-Me-C18:0) acid were dominated during growth on phenol and glucose. While in n-hexadecane grown cells main components of fatty acids pool were saturated tetradecanoic (C14:0) and hexadecanoic (C16:0) and unsaturated hexadecenoic (C16:1 cis-9) acids. The quantitative ratio of individual fatty acids of R. aetherivorans UCM Ac-602 cells differed depending on the substrate and incubation time. Under the influence of high phenol concentrations (1.5 g/L) there was a threefold increase in the ratio of straight-chain saturated to unsaturated fatty acids in comparison to cells grown on glucose and double increase compared to those grown on n-hexadecane. The amounts of 10-Мe-C18:0 fatty acid in cells grown on phenol were 1.8–3.2-fold higher in comparison to cells grown on glucose and 38.3–60.3-fold higher compared to those grown on n-hexadecane. In addition, the content of this acid in cells increased with increasing the time of incubation on phenol. Conclusions. A significant increase in the ratio of straightchain saturated to unsaturated fatty acids in the cells of R. aetherivorans UCM Ac-602 strain during growth on phenol and n-hexadecane in comparison to cells grown on glucose, as well as significant increase of methyl-branched (10-Me-C18:0) acid amount in phenol grown cells indicates the possible involvement of these fatty acids in the adaptation of the strain to the assimilation of toxic substances.

Photocatalytic degradation of tetracycline by metal-organic frameworks modified with Bi2WO6 nanosheet under direct sunlight

Porous metal-organic frameworks (MOFs) with visible-light response have attracted much attention in the field of environmental purification and solar energy conversion. In this study, MIL-100(Fe) was modified with Bi2WO6 nanosheets by a facile hydrothermal method to fabricate a photocatalyst with direct Z-scheme heterojunction. When treating the tetracycline (TC) solution under natural sunlight, 12 wt%MIL-100(Fe)/Bi2WO6 obtained the highest apparent rate constant of (6.59 ± 0.52)✕10−3 L mg−1 min−1, which was 16.1 and 3.9 times than that of pristine MIL-100(Fe) and Bi2WO6, respectively. In addition to explore the feasibility of sunlight-activated MIL-100(Fe)/Bi2WO6 to remove TC under various conditions, the degradation intermediates and their possible transformation pathway were provided with the aid of three-dimensional excitation−emission matrix spectra and liquid chromatography-mass spectrometry system. The results of Escherichia coli culture demonstrated that the biotoxicity variation of TC solution would first increase and then decrease with the photodegradation time. Ultimately, based on the results of bandgap calculation, radicals trapping and charge flow tracking experiments, the direct Z-scheme heterojunction between MIL-100(Fe) and Bi2WO6 nanosheets was confirmed and the photocatalytic mechanism for TC degradation was rationally proposed. This work enriched MOFs-based heterojunction photocatalysts and provided a promising method to eliminate hazardous TC from aqueous solution.

Development of porous carbon/polydimethylsiloxane thin-film solid-phase microextraction membranes to facilitate on-site sampling of volatile organic compounds

This work presents the development of carboxen/polydimethylsiloxane (Car/PDMS) based thin film-solid phase microextraction (TF-SPME) method capable of identifying volatile organic compounds (VOCs) in hot-tub-air and human-breath samples. The proposed TF-SPME membranes were developed using carbon mesh sheets loaded with Car/PDMS and nanocarbon/polydimethylsiloxane (NCar/PDMS) sorbents consistent with sustainable chemistry principles. The membrane surfaces were examined using a stereo microscope system and were evaluated based on the effect of various particle ratios (1%, 2.5%, 5%, 10%, and 15%). The results showed that membranes with higher particle ratios provided a higher extraction efficiency when used with McReynolds standards; however, membranes containing 10% and 15% carbon were fragile and suffered from substantially higher background bleed. Hence, a sorbent with a 5% particle ratio was deemed to be optimal, and the carboxen coating was found to capture the highest amounts of the McReynolds standard. Moreover, Car/PDMS and NCar/PDMS were found to provide good repeatability, as their intra-membrane %RSDs fell within an acceptable range—1.2%–21.9% and 1.7%–20%, respectively—for all analytes tested. Finally, for proof-of-concept applications, the developed membranes were used to sample chlorination by-products (chloroform and dichloroacetonitrile) from hot tub headspace and were identified using a hand portable gas chromatography-mass spectrometry (GC-MS) system. In second application 33 VOCs in human-breath samples sampled and identified using a benchtop GC-MS system.

Antidiabetic effect of Sophora pachycarpa seeds extract in streptozotocin-induced diabetic mice: a statistical evaluation

Undoubtedly, identification of the chemical composition of organic extracts or secondary metabolites of plant materials and evaluation of their potential bioactivity are among the main objectives of natural products-based investigations....

Evaluation of the toxicity and chemical alterations of deoxynivalenol degradation products under ozone treatment

Here, we studied the ozonolysis of deoxynivalenol (DON) in saturated aqueous ozone. We found that ozone can play an important role in the oxidation and degradation of DON. The reaction reached its peak within 5 min of treatment, and the degradation rate was approximately 70%. Toxicity analysis (CCK-8 analysis, ROS analysis, and apoptosis analysis) revealed that DON and saturated aqueous ozone treatments did not significantly change the toxicity of degradation products, and both could induce a decrease in the viability of A549 cells. The results of the metabolomics and cytotoxicity analysis were consistent. We used the Q Exactive Focus high-resolution liquid chromatography-mass spectrometry system to identify degradation products. Among the four identified degradation products, only the epoxy groups at the C12, C13 positions of C15H20O9 were opened. Because the epoxy groups at the C12, C13 positions in most degradation products were not opened based on the toxicity mechanism of DON, the toxicity of DON was not significantly reduced.

Chemical composition and phytotoxicity of essential oil from invasive plant, Ambrosia artemisiifolia L.

Essential oils have been evaluated as appropriate phytotoxins with mechanisms of action that are different from those of synthetic herbicides applied in weed management activities, but little is known about the effect of Ambrosia artemisiifolia essential oil (EO) on weeds. Here, the chemical composition of A. artemisiifolia EO was analyzed using a Gas Chromatography-Mass Spectrometry system. and the phytotoxic activities of the EO against monocot (Poa annua, Setaria viridis) and dicot (Amaranthus retroflexus, Medicago sativa) species are evaluated under laboratory and green-house conditions for the first time. The EO was rich in sesquiterpenes (62.51%), with germacrene D (32.92%), β-pinene (15.14%), limonene (9.90%), and caryophyllene (4.49%) being the major compounds based on Gas Chromatography-Mass Spectrometry analysis results. A. artemisiifolia EO inhibited seed germination and seedling development significantly in the tested species even at low concentrations (0.25 mg mL−1). In addition, bioassay results for the activities of superoxide dismutase (SOD) and peroxidase (POD) increased and then decreased with an increase in EO concentration. Unlike the enzymatic activity, root cell viability declined significantly in the tested weeds in all EO treatments. Besides, a foliar spray experiment resulted in visible injury in leaves and a decrease in chlorophyll content and eventually led to wilting of all tested weeds. The EO (0.25–5.00 mg mL−1) altered Allium cepa root tip cells with a decline in mitotic index and an increase in chromosomal aberrations after 24 h treatment. The cytotoxic evaluation confirmed the mitotic inhibitory effect of EO, although the intensity varied under different concentrations. According to the results, A. artemisiifolia EO has the potential applications as a natural herbicide owing to its phytotoxic activity; which also helps to explain their potential involvement in allelopathic interaction of volatile compounds present in the EO that facilitate the invasion success of the exotic species.

Tear Lipid Metabolites As Potential Diagnostic Biomarkers for Ocular Chronic Graft-Versus-Host Disease

Chronic graft-versus-host disease (cGVHD) remains a common threat after allogeneic hematopoietic cell transplantation (allo-HSCT), and ocular manifestations occur in up to 60% to 90% of cGVHD patients. We sought to reveal major metabolic dysregulation and to determine tear metabolites as potential biomarkers for ocular cGVHD. Twenty-three ocular cGVHD and 16 control tear samples were collected for this study. Differential metabolites were identified using a liquid chromatography-mass spectrometry system. Spearman's test was used to analyze the correlation between metabolites and ophthalmic indexes (National Institutes of Health [NIH] eye score, fluorescein tear film break-up time [T-BUT], corneal fluorescein staining [CFS], and Schirmer's test). Receiver operating characteristic (ROC) curve was analyzed to evaluate the prediction potential of identified metabolites for ocular cGVHD. Differential metabolites were mainly observed in lipid metabolites, and we highlighted the lipid dysregulation in glycerophospholipid metabolism, sphingolipid metabolism, and biosynthesis of unsaturated fatty acids. In glycerophospholipid metabolism, phosphatidylcholine (34:1) (PC [34:1]) exhibited the strongest correlation with NIH eye score (r=0.80), T-BUT (r=0.79), CFS (r=0.77), and Schirmer's test (r=0.69). In sphingolipid metabolism, sphingomyelin (SM) was the most consistent with T-BUT (r=0.74) and CFS (r=0.71), whereas lactosylceramide (LacCer) was the most consistent with NIH eye score (r=0.76) and Schirmer's test (r=0.64). In biosynthesis of unsaturated fatty acids, docosahexaenoic acid (DHA) had the highest correlation with NIH eye score (r=0.73), T-BUT (r=0.60), CFS (r=0.67) and Schirmer's test (r=0.67) (P < .0001 for all). ROC analysis revealed that area under the curve (AUC) values for PC (34:1) (AUC=0.967), LacCer (AUC=0.946), SM (AUC=0.932), and DHA (AUC=0.929) were significantly correlated with cGVHD (P < .0001 for all). Our study identified PC (34:1), SM, LacCer, and DHA as promising tear biomarkers to indicate metabolic dysregulation and ophthalmic manifestations in ocular cGVHD.

Shotgun Proteomics and Mass Spectrometry as a Tool for Protein Identification and Profiling of Bio-Carrier-Based Therapeutics on Human Cancer Cells.

Shotgun proteomics has been widely applied to study proteins in complex biological samples. Combination of high-performance liquid chromatography with mass spectrometry has allowed for comprehensive protein analysis with high resolution, sensitivity, and mass accuracy. Prior to mass spectrometry analysis, proteins are extracted from biological samples and subjected to in-solution trypsin digestion. The digested proteins are subjected for clean-up and injected into the liquid chromatography-mass spectrometry system for peptide mass identification. Protein identification is performed by analyzing the mass spectrometry data on a protein search engine software such as PEAKS studio loaded with protein database for the species of interest. Results such as protein score, protein coverage, number of peptides, and unique peptides identified will be obtained and can be used to determine proteins identified with high confidence. This method can be applied to understand the proteomic changes or profile brought by bio-carrier-based therapeutics in vitro. In this chapter, we describe methods in which proteins can be extracted for proteomic analysis using a shotgun approach. The chapter outlines important in vitro techniques and data analysis that can be applied to investigate the proteome dynamics.

Atmospheric phthalate pollution in plastic agricultural greenhouses in Shaanxi Province, China.

Phthalate pollution in soil and vegetables in plastic agricultural greenhouses has attracted wide concern. Investigating airborne phthalates in this environment can improve understanding of air-soil or air-vegetable phthalate migration. However, studies of phthalates in plastic agricultural greenhouse air are rare. To fill this gap, 25 gas-phase and 23 particle-phase samples were collected from 12 typical plastic greenhouses in Shaanxi. 16 types of phthalates were measured by a gas chromatography-mass spectrometry system (GC-MS) to analyse their pollution features and variations. Results showed that in the air of the plastic greenhouses, the median concentration of the sum of sixteen type phthalates (∑16 phthalates) was 5305ngm-3, with 5th-95th value of 1214-9616ngm-3. Phthalates in gas-phase samples were over 100 times higher than the levels in particle-phase samples. Air phthalate concentrations in the plastic greenhouses were higher than those in the control groups (P<0.05). Air bis (2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) accounted for 66.9% and 29.3% of total ∑16 phthalate concentrations, respectively. Air phthalate concentrations in the plastic greenhouses in winter were 1.1-5.3 times higher than the levels in summer respectively (P<0.05). Gas-particle partition coefficients (KP) values of DEHP in summer (median of 1.52×10-4m3μg-1) were higher than KP values of DnBP in summer (0.60×10-4m3μg-1). Log-transformed KP values of DnBP and DEHP were linear correlated to the reciprocal of air temperatures, respectively (P<0.05).

Induced sputum metabolomic profiles and oxidative stress are associated with chronic obstructive pulmonary disease (COPD) severity: potential use for predictive, preventive, and personalized medicine

Chronic obstructive pulmonary disease (COPD) is a highly heterogeneous disease, and metabolomics plays a hub role in predictive, preventive, and personalized medicine (PPPM) related to COPD. This study thus aimed to reveal the role of induced sputum metabolomics in predicting COPD severity. In this pilot study, a total of 20 COPD patients were included. The induced sputum metabolites were assayed using a liquid chromatography-mass spectrometry (LC-MS/MS) system. Five oxidative stress products (myeloperoxidase (MPO), superoxide dismutase (SOD), glutathione (GSH), neutrophil elastase (NE), and 8-iso-PGF2α) in induced sputum were measured by ELISA, and the metabolomic profiles were distinguished by principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA). The Kyoto Encyclopedia of Genes and Genomes (KEGG) was used for pathway enrichment analysis, and a significant difference in induced sputum metabolomics was observed between moderate and severe COPD. The KEGG analysis revealed that the glycerophospholipid metabolism pathway was downregulated in severe COPD. Due to the critical role of glycerophospholipid metabolism in oxidative stress, significant negative correlations were discovered between glycerophospholipid metabolites and three oxidative stress products (SOD, MPO, and 8-iso-PGF2α). The diagnostic values of SOD, MPO, and 8-iso-PGF2α in induced sputum were found to exhibit high sensitivities and specificities in the prediction of COPD severity. Collectively, this study provides the first identification of the association between induced sputum metabolomic profiles and COPD severity, indicating the potential value of metabolomics in PPPM for COPD management. The study also reveals the correlation between glycerophospholipid metabolites and oxidative stress products and their value for predicting COPD severity.

Mapping Complex Disulfide Bonds via Implementing Photochemical Reduction Online with Liquid Chromatography-Mass Spectrometry.

Assigning disulfide linkage is a crucial task for protein identification. The current bottom-up proteomics workflow has limitations in characterizing peptide digests containing multiple disulfide bonds due to the difficulty of controlling partial reduction via conventional chemical reduction methods. Previously, our lab reported the development of an acetone/2-propanol (IPA) photoinitiating system for rapid (on second time scale) and tunable disulfide bond reduction. Herein, we incorporated this reaction system onto a liquid chromatography-mass spectrometry (LC-MS) system for bottom-up protein analysis applications. The photochemical reduction reaction was implemented in a flow microreactor which allowed for up to 15 s 254 nm UV irradiation. The microreactor was installed post LC separation and right before electrospray ionization, while a T-junction was used to introduce the photoinitiating solution to the LC eluent before entering the microreactor. The degree of disulfide reduction was tunable from partial reduction to complete reduction for peptides containing one or multiple disulfide bonds. Significantly improved sequence coverage was obtained from complete disulfide reduction, while assignment of the disulfide connectivity was facilitated from partial disulfide reduction when coupled with tandem mass spectrometry via collision-induced dissociation. As a proof-of-concept test, trypsin digests of lysozyme (four disulfide bonds) and bovine serum albumin (BSA, 17 disulfide bonds) were analyzed by the LC-MS system coupled with online reduction. Sequence coverage was improved from 35% to 100% and 13% to 87% for lysozyme and BSA, respectively. All four disulfide bonds of lysozyme were determined. For BSA, nine disulfide bonds were characterized and eight adjacent disulfide bonds were narrowed down.

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4 +/15NH4 + Analyses via Sequential Conversion to N2O.

The importance of understanding the fate of nitrate (NO3-), which is the dominant N species transferred from terrestrial to aquatic ecosystems, has been increasing because global nitrogen loads have dramatically increased following industrialization. Dissimilatory nitrate reduction to ammonium (DNRA) and denitrification are both microbial processes that use NO3- for respiration. Compared to denitrification, quantitative determinations of the DNRA activity have been carried out only to a limited extent. This has led to an insufficient understanding of the importance of DNRA in NO3- transformations and the regulating factors of this process. The objective of this paper is to provide a detailed procedure for the measurement of the potential DNRA rate in environmental samples. In brief, the potential DNRA rate can be calculated from the 15N-labeled ammonium (15NH4+) accumulation rate in 15NO3- added incubation. The determination of the 14NH4+ and 15NH4+ concentrations described in this paper is comprised of the following steps. First, the NH4+ in the sample is extracted and trapped on an acidified glass filter as ammonium salt. Second, the trapped ammonium is eluted and oxidized to NO3- via persulfate oxidation. Third, the NO3- is converted to N2O via an N2O reductase deficient denitrifier. Finally, the converted N2O is analyzed using a previously developed quadrupole gas chromatography-mass spectrometry system. We applied this method to salt marsh sediments and calculated their potential DNRA rates, demonstrating that the proposed procedures allow a simple and more rapid determination compared to previously described methods.

Pharmacognostic, chemical and mucolytic activity study of Malva pseudolavatera Webb &amp; Berthel. and Malva sylvestris L. (Malvaceae) leaf extracts, grown in Ecuador

Abstract. Sarmiento-Tomalá GM, Miranda-Martínez M, Chóez-Guaranda IA, Gutiérrez-Gaitén YI, Delgado-Hernández R, Carrillo-Lavid G. 2020. Pharmacognostic, chemical and mucolytic activity study of Malva pseudolavatera Webb &amp; Berthel. and Malva sylvestris L. (Malvaceae) leaf extracts, grown in Ecuador. Biodiversitas 21: 4755-4763. Among the cultivated and/or native plant species of Ecuador, are those belonging to Malvaceae. Of these, the most traditionally used are Malva pseudolavatera Webb &amp; Berthel. and Malva sylvestris L., which are grown and sold in indigenous markets. Various articles have been published for M. sylvestris about its chemical composition and pharmacological properties; however, M. pseudolavatera lacks references and is the most commercialized in Ecuador. Therefore, this work sets the following objective: To carry out a comparative study of the pharmacognostic, chemical and mucolytic activity of the species M. pseudolavatera and M. sylvestris. The species studied were collected in the province of Chimborazo. Extracts were obtained with different solvents: water, hexane and 80% ethanol. The aqueous extract was used to determine the mucolytic activity; the hexane and alcoholic extracts were analyzed by the coupled gas chromatography-mass spectrometry system. It was found that M. pseudolavatera has a very similar chemical composition to M. sylvestris; The presence of fatty acids, di and triterpenoids, phytosterols and abundant amino acids was detected. Both species showed an important mucolytic effect, the activity of M. pseudolavatera being higher than the highest doses tested. These studies provide scientific data that allow demonstrating the high potentiality of extracts from the leaves of two Malva species as sources of plant material for possible research and development of phytotherapeutic products with mucolytic and gastroprotective activity in correspondence with their uses in traditional Ecuadorian herbal medicine.

The Connection between Urinary Equol Levels and the Prevalence of Atopic Dermatitis

Background: Soy isoflavones and their metabolites such as equol have been associated with a reduced risk of hormone-sensitive tumors and metabolic syndromes. However, individual soy isoflavones and equol levels in atopic dermatitis remain uninvestigated. Objective: The aim of this study is to compare the levels of urinary daidzein, genistein, and equol between atopic dermatitis patients and normal subjects and to examine the correlation between equol concentration and the severity of clinical symptoms. Methods: A cross-sectional study was conducted at Akita University Hospital and Aso Iizuka Hospital in Japan. Fifty patients with confirmed atopic dermatitis diagnosis and 67 healthy controls were recruited. Daidzein, genistein, and equol in urine were measured by using a high-performance liquid chromatography-mass spectrometry system. Results: Urinary equol levels were significantly lower in the atopic dermatitis patients than in the healthy controls (p = 0.002). The difference was particularly noticeable in young people (6–19 years, p < 0.001). No correlations were found between urinary equol levels and the severity of clinical symptoms and laboratory data in the atopic dermatitis patients. Conclusion: Equol levels in childhood might be involved in the development of atopic dermatitis.

Determination of vitamin D3 in daily oily supplements by a two-dimensional supercritical fluid chromatography-liquid chromatography-mass spectrometry system.

A two-dimensional system composed of supercritical fluid chromatography (SFC) and reverse phase liquid chromatography (RPLC) coupled a tandem mass spectrometry (MS) was developed for the quantitative analysis of vitamin D in daily oily supplements. Two six-port switching valves are configured, allowing four different valve positions. When the valve positions were fixed at Position A, this system worked at SFC-MS mode. When the valve positions switched between Position B and C, this system worked at a SFC-LC-MS switching mode. Vitamin D3 in two kinds of oily drops, Baby Ddrops and Vitamin AD drops, was determined at both SFC-MS and SFC-LC-MS switching modes by using the same system. The linearity, repeatability and recovery were investigated using the internal and external standard methods for the two modes. The results obtained from the internal standard method are better than those of the external standard method at either mode. The coefficient of determination (r2) for the internal standard method is more than 0.999, with a linear range of 20-1000μg/L. Both Baby Ddrops and Vitamin AD drops were analyzed with good repeatability (<3.21%) and recovery (94.1%-116.1%) using internal standard method. When calculated by the external standard method, as compared to SFC-MS mode, SFC-LC-MS switching mode has better linearity (r2>0.999), repeatability (Baby Ddrops: 4.45%, Vitamin AD drops: 1.12%) and recovery (86.3%-107.1%). The results indicate that the two-dimensional SFC-MS/SFC-LC-MS system is useful for determination of vitamin D in oily drops. If it works at SFC-MS mode, the internal standard is required. When SFC-LC-MS switching mode is used, external standard method can also obtain the accurate results with good precision.