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1.
Plants (Basel) ; 12(3)2023 Jan 21.
Article in English | MEDLINE | ID: mdl-36771585

ABSTRACT

Plant-associated bacteria in heavy-metal-contaminated environments could be a biotechnological tool to improve plant growth. The present work aimed to isolate lead- and cadmium-tolerant endophytic bacteria from the roots of Typha latifolia growing in a site contaminated with these heavy metals. Endophytic bacteria were characterized according to Pb and Cd tolerance, plant-growth-promoting rhizobacteria activities, and their effect on T. latifolia seedlings exposed and non-exposed to Pb and Cd. Pb-tolerant isolates were identified as Pseudomonas azotoformans JEP3, P. fluorescens JEP8, and P. gessardii JEP33, while Cd-tolerant bacteria were identified as P. veronii JEC8, JEC9, and JEC11. They all exert biochemical activities, including indole acetic acid synthesis, siderophore production, and phosphate solubilization. Plant-bacteria interaction assays showed that P. azotoformans JEP3, P. fluorescens JEP8, P. gessardii JEP33, and P. veronii JEC8, JEC9, JEC11 promote the growth of T. latifolia seedlings by increasing the root and shoot length, while in plants exposed to either 5 mg/L of Pb or 10 mg/L of Cd, all bacterial isolates increased the shoot length and the number of roots per plant, suggesting that they are plant-growth-promoting rhizobacteria that could contribute to T. latifolia adaptation to the heavy metal polluted site.

2.
3 Biotech ; 12(9): 210, 2022 Sep.
Article in English | MEDLINE | ID: mdl-35945985

ABSTRACT

In this work, we evaluated the removal efficiency of diclofenac by Chlorella vulgaris OW-01, Nannochloropsis oculata CCAP 849/7, Scenedesmus acutus UTEX 72, and Scenedesmus obliquus CCAP 276/2. Each microalga was grown in media with different concentrations (50 and 100% of the original formulation) of carbon, nitrogen, and phosphorus, to evaluate their effect on the removal of diclofenac. We also evaluated the photodegradation of diclofenac under the same conditions. The diclofenac removed from the media ranged from 59 to 92%, obtaining the highest removal with S. obliquus. The diclofenac adsorbed on the cell walls ranged from 12.2 to 26.5%, obtaining the highest adsorption with S. obliquus. The diclofenac degraded by light ranged from 15 to 28%. The nutrient deficit showed no influence on the removal of diclofenac in any of the microalgae under study. These results indicate that S. obliquus is the best alternative for the bioremediation of diclofenac. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-022-03268-2.

3.
J Environ Sci Health B ; 56(3): 282-291, 2021.
Article in English | MEDLINE | ID: mdl-33397190

ABSTRACT

In the present study, α-amylase and α-glucosidase inhibitory effect and antioxidant activity of capsaicin and piperine from the ethanolic extract of Capsicum chinense (EECch) and Piper nigrum (EEPn) fruits were investigated. Results revealed that EECch exhibited the highest phenolic (154 mg GAE/100 g of tissue) and flavonoid content (75 mg RtE/100 g of tissue) in comparison with EEPn. The predominant compound detected in EECch and EEPn by GC-EIMS analysis was the capsaicin and piperine, respectively. The capsaicin and piperine showed the highest α-amylase and α-glucosidase inhibitory effect and antioxidant activity rather than extracts. The EEPn (IC50= 216 µg/mL) and piperine (IC50= 105 µg/mL) present a highest α-amylase inhibitory effect, while the EECch (IC50= 225 µg/mL) and capsaicin (IC50= 117 µg/mL) showed highest anti-α-glucosidase activity. Molecular docking established that capsaicin and piperine bind at the α-glucosidase and α-amylase through hydrophobic interactions, hydrogen bond, and charge interactions with amino acid residues. The enzyme inhibitory activity and antioxidant properties exhibited by EECch and EEPn could be attributed to the capsaicin and piperine content and other compounds present such as phenolic compounds and flavonoids. These fruits are potential sources of natural antioxidant agents and α-amylase and α-glucosidase inhibitors.


Subject(s)
Alkaloids/pharmacology , Benzodioxoles/pharmacology , Capsaicin/pharmacology , Capsicum/chemistry , Enzyme Inhibitors/pharmacology , Piper nigrum/chemistry , Piperidines/pharmacology , Polyunsaturated Alkamides/pharmacology , alpha-Amylases/antagonists & inhibitors , Fruit/chemistry , Glycoside Hydrolase Inhibitors/pharmacology , Plant Extracts/chemistry
4.
Trop Anim Health Prod ; 53(1): 101, 2021 Jan 08.
Article in English | MEDLINE | ID: mdl-33417070

ABSTRACT

This study investigated Lippia palmeri Watt (oregano) phytochemical compounds, their antioxidant capacity, and immunological effects on goat peripheral blood leukocytes (PBL), and on the presence of intermediate polar compounds in goat feces fed dietary oregano. The polar and nonpolar fractions of L. palmeri W. were characterized and phytochemical contents and antioxidant capacity were determined. Twelve healthy Anglo-Nubian goats were used for the in vivo trials, which were randomly assigned to control fed with basal diet, or oregano group fed with basal diet + 2.6% (DM basis) dried oregano leaves. Goat peripheral blood leukocytes (PBL) were isolated for the in vitro study, and PBL were stimulated with oregano extracts at 100 and 150 µg/mL after 24 h. For the in vivo trial, dietary oregano (2.6% on DM basis) was evaluated in the goats for 90 days. Relatively high abundance of carvacrol and thymol phytochemical compounds was found in oregano. The highest antioxidant capacity of oregano extracts was detected at 100 and 150 µg/mL. Nitric oxide production, phagocytosis, and superoxide dismutase activities increased (p < 0.05) in stimulated PBL with oregano extracts, whereas the pro-inflammatory (TNF-α and IL-1ß) transcription and antioxidant (CAT and GPX-4) genes downregulated. In the in vivo experiment, dietary oregano enabled the detection of nine compounds found in goat feces, from which caproic (C6) was in a high relative quantity compared with the control group. Oregano has phytochemical compounds with strong antioxidant capacity that protect cells against oxidative stress damage and could modulate immune response and feces composition in goats.


Subject(s)
Antioxidants/pharmacology , Goats/physiology , Intestines/physiology , Leukocytes/immunology , Lippia/chemistry , Plant Extracts/metabolism , Plant Extracts/pharmacology , Animal Feed/analysis , Animals , Diet/veterinary , Dietary Supplements/analysis , Female , Plant Extracts/administration & dosage , Random Allocation
5.
Braz J Microbiol ; 52(1): 349-361, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33236245

ABSTRACT

In this work, we isolated four Cd-tolerant endophytic bacteria from Typha latifolia roots that grow at a Cd-contaminated site. Bacterial isolates GRC065, GRC066, GRC093, and GRC140 were identified as Pseudomonas rhodesiae. These bacterial isolates tolerate cadmium and have abilities for phosphate solubilization, siderophore production, indole acetic acid (IAA) synthesis, and ACC deaminase activity, suggesting that they are plant growth-promoting rhizobacteria. Bacterial inoculation in Arabidopsis thaliana seedlings showed that P. rhodesiae strains increase total fresh weight and number of lateral roots concerning non-inoculated plants. These results indicated that P. rhodesiae strains promote A. thaliana seedlings growth by modifying the root system. On the other hand, in A. thaliana seedlings exposed to 2.5 mg/l of Cd, P. rhodesiae strains increased the number and density of lateral roots concerning non-inoculated plants, indicating that they modify the root architecture of A. thaliana seedlings exposed to cadmium. The results showed that P. rhodesiae strains promote the development of lateral roots in A. thaliana seedlings cultivated in both conditions, with and without cadmium. These results suggest that P. rhodesiae strains could exert a similar role inside the roots of T. latifolia that grow in the Cd-contaminated environment.


Subject(s)
Arabidopsis/microbiology , Cadmium/metabolism , Cadmium/pharmacology , Plant Roots/microbiology , Pseudomonas/genetics , Pseudomonas/metabolism , Biodegradation, Environmental , Endophytes/genetics , Endophytes/metabolism , Phosphates/metabolism , Plant Development , Plant Roots/drug effects , Pseudomonas/drug effects , Pseudomonas/isolation & purification , Seedlings/drug effects , Seedlings/microbiology , Soil Pollutants , Solubility
6.
Materials (Basel) ; 13(24)2020 Dec 10.
Article in English | MEDLINE | ID: mdl-33321743

ABSTRACT

The search for sustainability in the Supply Chain (SC) is one of the tasks that most concerns business leaders in all manufacturing sectors because of the importance that the Supply Chain has as a transversal tool and due to the leading role that it has been playing lately. Of all the manufacturing sectors, this study focuses on the aerospace, shipbuilding, and automotive sectors identified as transport. The present study carries out a descriptive review of existing publications in these three sectors in relation to the sustainability of the Supply Chain in its 4.0 adaptation as an update in matters that are in constant evolution. Among the results obtained, Lean practices are common to the three sectors, as well as different technologies focused on sustainability. Furthermore, the results show that the automotive sector is the one that makes the greatest contribution in this sense through collaborative programs that can be very useful to the other two sectors, thus benefiting from the consequent applicable advantages. Meanwhile, the Aerospace and Shipbuilding sectors do not seem to be working on promoting a sustainable culture in the management of the Supply Chain or on including training programs for their personnel in matters related to Industry 4.0.

7.
Foods ; 9(12)2020 Dec 03.
Article in English | MEDLINE | ID: mdl-33287102

ABSTRACT

Highly branched neo-fructans (agavins) are natural prebiotics found in Agave plants, with a large capacity to mitigate the development of obesity and metabolic syndrome. Here, we investigated the impact of agavins intake on gut microbiota modulation and their metabolites as well as their effect on metabolic endotoxemia and low-grade inflammation in mice fed high-fat diet. Mice were fed with a standard diet (ST) and high-fat diet (HF) alone or plus an agavins supplement (HF+A) for ten weeks. Gut microbiota composition, fecal metabolite profiles, lipopolysaccharides (LPS), pro-inflammatory cytokines, and systemic effects were analyzed. Agavins intake induced substantial changes in gut microbiota composition, enriching Bacteroides, Parabacteroides, Prevotella, Allobaculum, and Akkermansia genus (LDA > 3.0). l-leucine, l-valine, uracil, thymine, and some fatty acids were identified as possible biomarkers for this prebiotic supplement. As novel findings, agavins supplementation significantly decreased LPS and pro-inflammatory (IL-1α, IL-1ß, and TNF-α; p < 0.05) cytokines levels in portal vein. In addition, lipid droplets content in the liver and adipocytes size also decreased with agavins consumption. In conclusion, agavins supplementation mitigate metabolic endotoxemia and low-grade inflammation in association with gut microbiota regulation and their metabolic products, thus inducing beneficial responses on metabolic disorders in high-fat diet-fed mice.

8.
J Phys Chem Lett ; 11(19): 8008-8016, 2020 Oct 01.
Article in English | MEDLINE | ID: mdl-32840378

ABSTRACT

The pandemic caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has quickly spread globally, infecting millions and killing hundreds of thousands of people. Herein, to identify potential antiviral agents, 97 natural amide-like compounds known as alkamides and piperamides were tested against SARS-CoV-2 main protease (Mpro) and RNA-dependent RNA polymerase (RdRp), and the human angiotensin-converting enzyme 2 (ACE2) using molecular docking and molecular dynamics simulations. The docking results showed that alkamides and dimeric piperamides from Piper species have a high binding affinity and potential antiviral activity against SARS-CoV-2. The absorption, distribution, metabolism, and excretion (ADME) profile and Lipinski's rule of five showed that dimeric piperamides have druglikeness potential. The molecular dynamics results showed that pipercyclobutanamide B forms a complex with Mpro at a similar level of stability than N3-I. Our overall results indicate that alkamides and piperamides, and specifically pipercyclobutanamide B, should be further studied as compounds with SARS-CoV-2 antiviral properties.


Subject(s)
Amides/pharmacology , Antiviral Agents/pharmacology , Antiviral Agents/therapeutic use , Benzodioxoles/pharmacology , Benzodioxoles/therapeutic use , Coronavirus Infections/drug therapy , Piper/chemistry , Piperidines/pharmacology , Piperidines/therapeutic use , Pneumonia, Viral/drug therapy , Amides/chemistry , Amides/therapeutic use , Angiotensin-Converting Enzyme 2 , Antiviral Agents/pharmacokinetics , Benzodioxoles/pharmacokinetics , Betacoronavirus/drug effects , COVID-19 , Coronavirus 3C Proteases , Cysteine Endopeptidases , Humans , Models, Molecular , Molecular Docking Simulation , Molecular Dynamics Simulation , Pandemics , Peptidyl-Dipeptidase A/drug effects , Piperidines/pharmacokinetics , SARS-CoV-2 , Viral Nonstructural Proteins/antagonists & inhibitors
9.
J Hazard Mater ; 390: 122186, 2020 05 15.
Article in English | MEDLINE | ID: mdl-32006852

ABSTRACT

Naphthenic acids (NAs) are complex mixtures of carboxylic acids from petroleum that have industrial applications and that may be released to the environment after oil spills. There is significant research on the chemical composition and toxicity of water-soluble NAs derived from oil sands mining in Alberta, Canada. Yet, little is known about low molecular weight organic compounds (LMWOC) from these sources. Headspace solid-phase microextraction coupled to gas chromatography-electron impact mass spectrometry was used for LMWOC profiling of commercial NA blends, and an acid-extractable organics (AEOs) mixture from a tailings pond. From Sigma 1, Sigma 2, Merichem NAs and the AEO extract, 54, 56, 40 and 4 compounds were identified, respectively. These include aliphatic and cyclic hydrocarbons, carboxylic acids, alkylbenzenes, phenols, naphthalene and alkyl-naphthalene, and decalin compounds. A sample of oil sands process-affected water (OSPW) and aqueous solutions of the NA blends were evaluated for matrix effects on LMWOC profiles. Principal component and clustering analyses revealed that LMWOC profiles of commercial extracts were closely related but distinct from the AEO and OSPW samples. Some of the identified LMWOC are reported to be genotoxic or carcinogenic, and therefore the NA mixtures and AEOs should be considered hazardous materials and further evaluated.

10.
Heliyon ; 6(1): e03137, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31922049

ABSTRACT

In the search of new and safe antibacterial compounds, the quorum sensing system (QS) modulation by natural products has been studied. As a result, many plant-derived compounds have been identified as potent quorum sensing inhibitors. Piper nigrum L. (black pepper) ethanolic extract inhibits the QS in some Gram-negative bacteria but the active components have not been previously identified. Thus, the objective of this work was to identify the P. nigrum peppercorns main components that block the QS, applying bioassay and chromatographic techniques. Piperine and trichostachine were identified as the main components responsible for the quorum quenching (QQ) activity of P. nigrum peppercorns extract. Piperine at 30 mg/L, decreased the violacein production by Chromobacterium violaceum CV026 by 35%, without affecting bacterial growth. Piperine concentration of 40 mg/L decreases violacein production by C. violaceum CV026 by 70% and growth in only 4.34%. Trichostachine at 50 mg/L decreases violacein production by C. violaceum CV026 by 12%, without affecting bacterial growth. P. nigrum extract concentration of 0.5 g/L decreased violacein production in 40 % and no effects on growth were observed. Neither P. nigrum extract, piperine, nor trichostachine did affect QS of Pseudomonas aeruginosa PAO1. Data here described exhibit the potential of piperamides as modulators of QS, not previously reported.

11.
Materials (Basel) ; 12(12)2019 Jun 23.
Article in English | MEDLINE | ID: mdl-31234610

ABSTRACT

Titanium alloys are widely used in important manufacturing sectors such as the aerospace industry, internal components of motor or biomechanical components, for the development of functional prostheses. The relationship between mechanical properties and weight and its excellent biocompatibility have positioned this material among the most demanded for specific applications. However, it is necessary to consider the low machinability as a disadvantage in the titanium alloys features. This fact is especially due to the low thermal conductivity, producing significant increases in the temperature of the contact area during the machining process. In this aspect, one of the main objectives of strategic industries is focused on the improvement of the efficiency and the increase of the service life of the elements involved in the machining of this alloy. With the aim to understand the most relevant effects in the machinability of the Ti6Al4V alloy, an analysis is required of different variables of the machining process like tool wear evolution, based on secondary adhesion mechanisms, and the relation between surface roughness of the work-pieces with the cutting parameters. In this research work, a study on the machinability of Ti6Al4V titanium alloy has been performed. For that purpose, in a horizontal turning process, the influence of cutting tool wear effects has been evaluated on the surface finish of the machined element. As a result, parametric behavior models for average roughness (Ra) have been determined as a function of the machining parameters used.

12.
Fish Shellfish Immunol ; 86: 420-428, 2019 Mar.
Article in English | MEDLINE | ID: mdl-30502468

ABSTRACT

Chenopodium ambrosioides L. has been used for centuries as traditional medicine in many clinical situations. The objectives of this study were first to assess the nutraceutical potential of C. ambrosioides L. extract through analyses of its chemical composition and antioxidant properties, followed by assessing toxicity and antioxidative activities on fish splenocytes. The second one was to perform an in vivo study using dietary C. ambrosioides L. extract (0.0, 0.5, 1.0 and 2.0%; w/w) for 15 and 30 days (2-week and 4-week treatments) to assess associated-intestine health status by short-chain fatty production, antioxidant enzyme activities and anti-inflammatory effects on Pacific red snapper (Lutjanus peru). Non-polar and polar fractions were detected by gas chromatography/mass spectrometry (GC-MS) in C. ambrosioides, of which the most abundant compounds were carvacrol, phytol, squalene, vitamin E and sucrose. The extract of C. ambrosioides L. enhanced a considerable antiradical and reducing power; fish splenocytes responded positively with higher (88%) cell viability than control. The production of nitric oxide and superoxide anion, as well as superoxide dismutase and catalase activities, were also enhanced in splenocytes treated with C. ambrosioides L. The in vivo study results showed that acetate was the major short-chain fatty acid found in fish receiving C. ambrosioides L. after week four. Pro-inflammatory cytokine gene expression in intestine was modulated in fish fed with C. ambrosioides L. at any time of the experimental trial. In addition, the histological findings suggested that its extract did not cause inflammatory damage in intestine. Overall, the results suggest that C. ambrosioides L. is safe for immune cells and promoting intestinal health status of fish through antioxidant and anti-inflammatory effects, making it an interesting additive in functional diets.


Subject(s)
Anti-Inflammatory Agents/pharmacology , Antioxidants/metabolism , Chenopodium ambrosioides/chemistry , Intestines/immunology , Perciformes/immunology , Animal Feed/analysis , Animals , Anti-Inflammatory Agents/administration & dosage , Diet/veterinary , Dietary Supplements/analysis , Dose-Response Relationship, Drug , Fatty Acids, Volatile/analysis , In Vitro Techniques , Plant Leaves/chemistry , Time Factors
13.
Materials (Basel) ; 11(8)2018 Aug 18.
Article in English | MEDLINE | ID: mdl-30126182

ABSTRACT

Plastic matrix composite materials are an excellent choice for structural applications where high strength-weight and stiffness-weight ratios are required. These materials are being increasingly used in diverse industrial sectors, particularly in aerospace. Due to the strict tolerances required, they are usually machined with drilling cycles due to the type of mounting through rivets. In this sense, laser beam drilling is presented as an alternative to conventional drilling due to the absence of tool wear, cutting forces, or vibrations during the cutting process. However, the process carries with it other problems that compromise the integrity of the material. One of these is caused by the high temperatures generated during the interaction between the laser and the material. In this work, variance analysis is used to study the influence of scanning speed and frequency on macro geometric parameters, surface quality, and defects (taper and heat affected zone). Also, in order to identify problems in the wall of the drill, stereoscopic optical microscopy (SOM) and scanning electron microscopy (SEM) techniques are used. This experimental procedure reveals the conditions that minimize deviations, defects, and damage in machining holes.

14.
Materials (Basel) ; 11(7)2018 Jul 18.
Article in English | MEDLINE | ID: mdl-30022001

ABSTRACT

One of the main criteria for the establishment of the performance of a forming process by material removal is based on cutting tool wear. Wear is usually caused by different mechanisms, however, only one is usually considered as predominant or the controller of the process. This experimental research is focused on the application of Pin-on-Disc wear tests, in which the tribological interference between UNS A92024-T3 Aluminum⁻Copper alloy and tungsten carbide (WC⁻Co) has been studied. The main objective of this study is focused on the determination of the predominant wear mechanisms involved in the process, as well as the characterization of the sliding and friction effects by using SEM and Energy Dispersion Spectroscopy (EDS) techniques, as applied to WC⁻Co (cutting tool material)/Al (workpiece material) which are widely used in the aerospace industry. Performed analysis prove the appearance of abrasive wear mechanisms prior to adhesion. This fact promotes adhesion mechanisms in several stages because of the surface quality deterioration, presenting different alloy composition in the form of a Built-Up Layer (BUL)/Built-Up Edge (BUE).

15.
Materials (Basel) ; 12(1)2018 Dec 30.
Article in English | MEDLINE | ID: mdl-30598017

ABSTRACT

The incorporation of plastic matrix composite materials into structural elements of the aeronautical industry requires contour machining and drilling processes along with metallic materials prior to final assembly operations. These operations are usually performed using conventional techniques, but they present problems derived from the nature of each material that avoid implementing One Shot Drilling strategies that work separately. In this work, the study focuses on the evaluation of the feasibility of Abrasive Waterjet Machining (AWJM) as a substitute for conventional drilling for stacks formed of Carbon Fiber Reinforced Plastic (CFRP) and aluminum alloy UNS A97050 through the study of the influence of abrasive mass flow rate, traverse feed rate and water pressure in straight cuts and drills. For the evaluation of the straight cuts, Stereoscopic Optical Microscopy (SOM) and Scanning Electron Microscopy (SEM) techniques were used. In addition, the kerf taper through the proposal of a new method and the surface quality in different cutting regions were evaluated. For the study of holes, the macrogeometric deviations of roundness, cylindricity and straightness were evaluated. Thus, this experimental procedure reveals the conditions that minimize deviations, defects, and damage in straight cuts and holes obtained by AWJM.

16.
Coronel Oviedo; s.n; 2018; 20180000. 66 p.
Thesis in Spanish | LILACS, BDNPAR | ID: biblio-1021596

ABSTRACT

Introducción: Los trastornos hipertensivos son la primera causa de muerte materna en los países desarrollados y la tercera causa de muerte materna en los países en vías de desarrollo. La preeclampsia es una enfermedad de origen desconocido y multifactorial cuyo tratamiento definitivo es el parto, además de ser causal de repercusiones sobre la madre y el recién nacido. Objetivo: El objetivo general del estudio fue determinar la Prevalencia de preeclampsia en embarazadas en el servicio de ginecología y obstetricia del hospital central del instituto de previsión social, 2017. Materiales y métodos: Estudio observacional descriptivo retrospectivo de corte transversal, con muestreo no probabilístico de casos consecutivos. Fueron incluidas todas las embarazadas con preeclampsia que acudieron al Servicio de Ginecología y Obstetricia del Hospital Central de Instituto de Previsión Social en el periodo comprendido entre los meses de enero a diciembre del año 2017. Resultados: Se realizó un estudio observacional descriptivo retrospectivo en 375 pacientes que acudieron al Hospital Central del Instituto de Previsión Social en el año 2017. Los resultados arrojaron que el 38,4% presentó preeclampsia de las cuales 63,2% presentaba en preeclampsia leve y 36,8% presentaba preeclampsia severa Entre los factores de riesgo el que apareció en mayor cantidad fue la Hipertensión Arterial Crónica. En cuanto a las complicaciones maternas se presentan en mayoría Hepáticas, Neurológicas y Renales. Conclusión: Los resultados de este estudio realizado en un centro de referencia nacional y de alta complejidad coinciden con estudio previo, determina datos importantes acerca de la prevalencia de preeclampsia.


Subject(s)
Humans , Female , Pregnancy , Adolescent , Adult , Young Adult , Pre-Eclampsia/epidemiology , Paraguay/epidemiology , Parity , Pre-Eclampsia/classification , Pre-Eclampsia/diagnosis , Prenatal Care , Socioeconomic Factors , Chronic Disease , Prevalence , Cross-Sectional Studies , Retrospective Studies , Risk Factors , Gestational Age , Marital Status , Abruptio Placentae/epidemiology , Educational Status , Abortion , Hypertension/complications
17.
Talanta ; 162: 440-452, 2017 Jan 01.
Article in English | MEDLINE | ID: mdl-27837854

ABSTRACT

In this study, we report for the first time the efficiency of pentafluorobenzyl bromide (PFBBr) for naphthenic acid (NA) mixtures derivatization, and the comparison in the optimal conditions to the most common NAs derivatization reagents, BF3/MeOH and N-(t-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA). Naphthenic acids are carboxylic acid mixtures of petrochemical origin. These compounds are important for the oil industry because of their corrosive properties, which can damage oil distillation infrastructure. Moreover, NAs are commercially used in a wide range of products such as paint and ink driers, wood and fabric preservatives, fuel additives, emulsifiers, and surfactants. Naphthenic acids have also been found in sediments after major oils spills in the United States and South Korea. Furthermore, the toxicity of the oil sands process-affected water (OSPW), product of the oil sands extraction activities in Canada's oil sands, has largely been attributed to NAs. One of the main challenges for the chromatographic analysis of these mixtures is the resolution of the components. The derivatization optimization was achieved using surface response analysis with molar ratio and time as factors for derivatization signal yield. After gas chromatography-electron impact mass spectrometry (GC/EIMS) analysis of a mixture of NA standards, it was found that the signal produced by PFB-derivatives was 2.3 and 1.4 times higher than the signal produced by methylated and MTBS-derivatives, respectively. The pentafluorobenzyl derivatives have a characteristic fragment ion at 181m/z that is diagnostic for the differentiation of carboxylic and non-carboxylic acid components within mixtures. In the analysis of a Sigma and a Merichem derivatized oil extract NA mixtures, it was found that some peaks lack the characteristic fragment ion; therefore they are not carboxylic acids. Open column chromatography was used to obtain a hexane and a methanol fraction of the Sigma and Merichem mixtures. The components in the hexane fraction, presumably hydrocarbons that did not react with PFBBr were ~7% by weight. The effectiveness of PFBBr was confirmed when the two NA oil extracts were spiked with 8 distinct NA standards and identified by GC/EIMS in the methanol fraction. Here, we also report retention indices of the methyl, MTBS and PFB derivatives of these 8 NAs. The use of PFBBr increases sensitivity, chromatographic resolution, and identification accuracy for the analysis of standards and mixtures of NAs compared to MTBSTFA and BF3/MeOH. This methodology will have wide applications in the elucidation of NA mixtures.

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