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1.
Anal Chem ; 93(3): 1604-1611, 2021 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-33356171

RESUMO

Carboxylic metabolites are an important class of metabolites, which widely exist in mammals with various types. Chemical isotope labeling liquid chromatography-mass spectrometry (CIL-LC-MS) has been widely used for the detection of carboxylated metabolites. However, high coverage analysis of carboxylated metabolites in biological samples is still challenging due to improper reactivity and selectivity of labeling reagents to carboxylated metabolites. In this study, we used N-methylphenylethylamine (MPEA) to label various types of carboxylated metabolites including short-chain fatty acids (SCFAs), medium-chain fatty acids (MCFAs), long-chain fatty acids (LCFAs), polycarboxylic acids (polyCAs), amino acids (AAs), and aromatic acids. Additionally, metabolites containing other functional groups, such as phenol, sulfhydryl, and phosphate groups, could not be labeled under the conditions of MPEA labeling. After MPEA labeling, the detection sensitivity of carboxylic acids was increased by 1-2 orders of magnitude, and their chromatographic retention on a reversed-phase (RP) column was enhanced (RT > 3 min). Under optimized labeling conditions, we used MPEA and d3-N-methylphenylethylamine (d3-MPEA) for high coverage screening of carboxylated metabolites in HepG2 cells by ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS). As a result, a total of 403 potential carboxylated metabolites were obtained of which 68 were confirmed based on our established in-house chemically labeled metabolite database (CLMD). SCFAs, MCFAs, LCFAs, polyCAs, AAs, and aromatic acids were all detected in HepG2 cell extracts. Due to the successful identification of AAs, the current method increased the coverage of carboxylated metabolites compared with our previous work. Moreover, 133 and 109 carboxylated metabolites with changed contents were obtained in HepG2 cells incubated with curcumin and R-3-hydroxybutyric acid, respectively. In general, our established method realized high coverage analysis of carboxylated metabolites in HepG2 cells.


Assuntos
Aminoácidos/análise , Ácidos Carboxílicos/análise , Ácidos Graxos/análise , Metanfetamina/análogos & derivados , Aminoácidos/metabolismo , Ácidos Carboxílicos/metabolismo , Cromatografia Líquida de Alta Pressão , Ácidos Graxos/metabolismo , Células Hep G2 , Humanos , Espectrometria de Massas , Metanfetamina/química , Metanfetamina/metabolismo , Estrutura Molecular
2.
J Chromatogr A ; 1628: 461478, 2020 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-32822996

RESUMO

This research developed a new methodology using a gas chromatograph, a pulsed discharge helium ionization detector (PDHID), and two mass spectrometric (MSD) detectors. The detectors worked simultaneously, using 8 columns and 7 valves. This new proposal for simultaneous analysis, with a single injection and analysis time of 36 min, allowed the quantification of 10 oxygenated compounds (alcohols, ketones and carboxylic acids), 3 permanent gases, 3 sulphides and 4 thiols, which are aggressive inhibitors of the Ziegler-Natta catalytic systems. The RSD (n = 6) for repeatability of the peak area of the 20 compounds analyzed, and the retention time were less than 0.59 and 0.23% respectively. The RSD (n = 6) for intermediate precision for the peak area was less than 0.85% and, for the retention time, less than 0.35%. 95% of the inhibitors analyzed showed relative errors inter and intra-day less than 3%. The inhibitors detected and quantified were: formic acid (2 to 45.32 ppm), acetic acid (1 to 25.32 ppm), acetone (5 to 72.67 ppm), methanol (1 to 39.93 ppm), isopropyl alcohol (2 to 74.88 ppm), ethanol (0.1 to 57.51 ppm), 1-propanol (0.1 to 92.36 ppm), 1-butanol (5 to 92.36 ppm), 2-butanol (5 to 95.15 ppm), tert-butanol (5 to 90.22 ppm), CO2 (0.5 to 5.0 ppm), CO (0.002 to 5.049 ppm), O2 (0.5 to 6.5 ppm), CH3(CH2)3SH (0.025 to 2.238 ppm), CH3CH2SH (0.025 to 1.595 ppm), COS (0.025 to 1.477 ppm), CH3SH (0.025 to 1.223 ppm), CH3(CH2)2SH (0.025 to 1.880 ppm), CS2 (0.025 to 1.929 ppm), H2S (0.025 to 0.847 ppm) and tert-butylmercaptan (0.025 to 2.283 ppm). These compounds generated reductions of between 5 and 20% in polypropylene production, representing losses of several million dollars. Therefore, a multilinear regression model was developed to predict this percentage of production loss in a fluidized bed reactor, based on the quantified inhibitors. The model has a correlation coefficient of 0.91 and a standard deviation of 1.12, allowing comparisons between actual and predicted experimental values. P values are less than 0.05, indicating that each inhibitor has a statistically significant effect on the model.


Assuntos
Alcenos/análise , Gases/análise , Indústrias , Oxigênio/análise , Compostos de Sulfidrila/análise , Sulfetos/análise , Álcoois/análise , Ácidos Carboxílicos/análise , Catálise , Cromatografia Gasosa-Espectrometria de Massas , Cetonas/análise , Limite de Detecção , Modelos Lineares , Espectrometria de Massas , Polipropilenos , Reprodutibilidade dos Testes
3.
Environ Pollut ; 266(Pt 3): 115043, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32623247

RESUMO

A new derivatization reagent, 2,3,4,5,6-pentafluorobenzyl bromide (PFBBr), was employed to determine seven perfluoroalkyl carboxylic acids (PFCAs) simultaneously in tap water with gas chromatography-mass spectrometry (GC-MS) technique in this study. Firstly, seven PFCAs were derivatized to their corresponding esters under alkaline condition. The derivatization conditions including the amount of PFBBr and K2CO3, derivatization temperature and time were optimized to increase the derivatization efficiency. The 14 tap water samples collected from different places of China were enriched and purified through solid phase extraction pretreatment. The limits of detection (LODs) and the limits of quantitation (LOQs) ranged from 0.1 ng/L to 0.28 ng/L and from 0.3 ng/L to 0.84 ng/L, respectively. The new method offers a linear relationship in the range from 2 ng/L to 2000 ng/L, and the correlation coefficients ranged from 0.9938 to 0.9994. The results showed that GC-MS combined with pre-column derivatization is a reliable method for the analysis of PFCAs in the aqueous environment.


Assuntos
Fluorcarbonetos/análise , Poluentes Químicos da Água/análise , Ácidos Carboxílicos/análise , China , Fluorbenzenos , Cromatografia Gasosa-Espectrometria de Massas
4.
Water Res ; 184: 116207, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32717490

RESUMO

Per- and polyfluoroalkyl substances (PFASs) are a group of persistent contaminants detected in firefighting foam impacted waters. Previous studies have performed suspect and non-target screening by high-resolution mass spectrometry (HRMS) to determine the composition of PFAS contamination and to discover unknown PFASs. Here, we performed a profile analysis with suspect screening against two lists in the NORMAN Suspect List Exchange in firefighting foam impacted environmental and drinking water (n = 18) collected in Okinawa, Japan, in April 2019. Samples were analyzed by liquid chromatography (LC) quadrupole time-of-flight (QTOF) MS in electron spray ionization mode. Suspect screening returned 116 candidate PFASs with their molecular weights, functional groups, and perfluoroalkyl chain lengths. Long-chain perfluoroalkyl acids (PFAAs) and some of their precursors were specifically found around the firefighting training area. Short-chain PFAAs were assumed to be formed from precursors by environmental processes. Perfluoroalkyl sulfonamide precursors were found to be transformed to perfluoroalkyl sulfonic acids (PFSAs) in the drinking water treatment process. In contrast, biological activated carbon filtration formed perfluoroalkyl carboxylic acids (PFCAs). The PFAS profile showed that a large number of different substances needs to be considered.


Assuntos
Água Potável , Fluorcarbonetos , Poluentes Químicos da Água , Ácidos Carboxílicos/análise , Fluorcarbonetos/análise , Japão , Poluentes Químicos da Água/análise
5.
Food Chem ; 333: 127540, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32682226

RESUMO

A novel of magnetic dummy-template molecularly imprinted polymers (mag-MWCNTs-DMIPs) were prepared by surface molecular imprinting technique. The structure of polymers were characterized and the binding properties were assessed by adsorption experiments. The synthetic mag-MWCNTs-DMIPs exhibit satisfying adsorption capacity, excellent selectivity and fast adsorption rate toward phenoxy carboxylic acid (PCA) herbicides. Afterwards, a reliable analytical method for selective separation and determination of trace PCA herbicides in cereals was established by using magnetic solid-phase extraction (mag-MWCNTs-DMIPs as magnetic adsorbent) and UPLC-MS/MS detection. A series of requisite factors were optimized in detail to achieve expected extraction performance. Under the optimum MSPE parameters, the mean spiked recoveries for analytes in different cereals ranged from 86.7% to 95.2% with intra- and inter-day precision not greater than 8.5% and 10.6%, respectively. At last, the developed method was successfully utilized for determination the four PCA herbicides in actual cereals.


Assuntos
Ácidos Carboxílicos/análise , Ácidos Carboxílicos/isolamento & purificação , Grão Comestível/química , Herbicidas/química , Impressão Molecular , Nanotubos de Carbono/química , Extração em Fase Sólida/métodos , Adsorção , Ácidos Carboxílicos/química , Contaminação de Alimentos/análise , Imãs/química , Polímeros/síntese química , Polímeros/química , Fatores de Tempo
6.
Science ; 368(6495): 1103-1107, 2020 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-32499438

RESUMO

The toxicity and environmental persistence of anthropogenic per- and poly-fluoroalkyl substances (PFAS) are of global concern. To address legacy PFAS concerns in the United States, industry developed numerous replacement PFAS that commonly are treated as confidential information. To investigate the distribution of PFAS in New Jersey, soils collected from across the state were subjected to nontargeted mass-spectral analyses. Ten chloroperfluoropolyether carboxylates were tentatively identified, with at least three congeners in all samples. Nine congeners are ≥(CF2)7 Distinct chemical formulas and structures, as well as geographic distribution, suggest airborne transport from an industrial source. Lighter congeners dispersed more widely than heavier congeners, with the most widely dispersed detected in an in-stock New Hampshire sample. Additional data were used to develop a legacy-PFAS fingerprint for historical PFAS sources in New Jersey.


Assuntos
Ácidos Carboxílicos/análise , Conservação dos Recursos Naturais , Éteres/análise , Fluorcarbonetos/análise , Solo/química , Ácidos Carboxílicos/toxicidade , Éteres/toxicidade , Fluorcarbonetos/toxicidade , Espectrometria de Massas , New Jersey
7.
J Chromatogr A ; 1622: 461132, 2020 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-32402494

RESUMO

A novel and simple derivatization method using a series of amide acetals as derivatization reagents, along with gas chromatography tandem mass spectrometry (GC-MS/MS) analysis, were developed and validated for simultaneous determination of 9 perfluoroalkyl carboxylic acids (PFCAs) in this study. The structures and fragmentation pathway of PFCAs derivatives were deduced and verified. The derivatization method developed in this study improved the sensitivity of the detection of PFCAs by GC. The applicability of 6 amide acetals for the derivatization of PFCAs was demonstrated. Derivatization conditions for 9 PFCAs were optimized with addition of 20 µL of derivatization reagent and reaction at 35 °C for 30 min. 9 PFCAs derivatives were confirmed to be stable over 15 days. The instrument detection limits (IDLs) were lower than 0.01 pg/µL. The intra and inter-day precisions were below 4.06% and 5.48%, respectively. To demonstrate the utility of the derivatization method, the level of PFCAs in the marine products were detected. The alkaline digestion followed by solid-phase extraction (SPE) cleanup method was used for pretreatment. The method detection limits (MDLs) ranged from 0.04 to 0.10 ng/g, and the spiked recoveries ranged between 54.72% and 107.29%, with relative standard deviation (RSD) of 1.53%-11.89%. Five PFCAs were detected in the range of 0.66 to 499.03 ng/g dry weight.


Assuntos
Acetais/química , Amidas/química , Ácidos Carboxílicos/análise , Fluorcarbonetos/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Espectrometria de Massas em Tandem/métodos , Organismos Aquáticos/química , Dimetilformamida/química , Limite de Detecção , Padrões de Referência
8.
J Chromatogr A ; 1621: 461066, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32299623

RESUMO

The ion-exchange and complex forming equilibria were quantitatively described and demonstrated in order to understand major factors in the control of selectivity in the analytical separation of carboxylic acids and inorganic anions in cryptand based ion chromatography. A complex retention model has been developed for the separation on a non-conventional IC column. Changes in retention are treated both theoretically and experimentally. Retention mechanism is employed on a macrocycle-based (cryptand n-decyl-[2.2.2]) ion-exchange chromatographic phase to improve the selectivity for a mixture of model analytes. We introduced an alternative internal gradient method by mixed eluent (i.e. eluents formed by combination of two alkali hydroxide with different molar ratio). The effect of binary mixed eluent (Li/Na, Li/K) on the retention behavior and peak shape of carboxylic acids are also discussed in view of the proposed theory. It was shown that the effects of binary aqueous mobile phases, held isocratically behave very similar to the step gradient mode. The "internal gradient" separation system has advantages over traditional step gradient mode. Twenty-six anions of widely varying chemical character (mono-, di-, tri-valent inorganic anions, mono-, di-, tri-valent aliphatic carboxylic acids, aromatic- and haloacetic carboxylic acids) were investigated on the cryptand-based (D222) stationary phase using different methods by LiOH, NaOH and KOH eluent. The predicted vs measured retention data are in rather good agreement. High degree of linearity was obtained for inorganic anions, multivalent carboxylic acids, and for aromatic and haloacetic acids R2 = 0.992, 0.969, and 0.980, respectively.


Assuntos
Ácidos Carboxílicos/análise , Cromatografia por Troca Iônica/métodos , Éteres Cíclicos/química , Bases de Schiff/química , Ácidos/química , Ânions/química , Ácidos Carboxílicos/isolamento & purificação , Troca Iônica
9.
Ecotoxicol Environ Saf ; 194: 110404, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32146197

RESUMO

Conversion of perfluoroalkyl acid (PFAA) precursors in the environment has been a hotspot research in recent years. This study firstly determined the spatial distribution of PFAAs and their precursors including 8:2 fluorotelomer unsaturated acid (8:2 FTUCA), perfluorooctane sulfoneamide (FOSA), and diperfluorooctane sulfonamido ethanol-based phosphate (di-SAmPAP), then investigated the conversion of the potential precursors in the seawater and sewage treatment plants (STPs) effluents. The results indicated that the target pollutants showed a typical concentration gradient from nearshore to offshore. And the obviously increased concentration of perfluorinated carboxylic acids (△[PFCAs]) after oxidation treatment can verify the existence of PFAA precursors in the seawater and STP effluents. The concentrations of PFCAs with carbon atom numbers 4-9 (PFCAC4-C9) revealed the most increase. Moreover, the levels of △[PFCAs] and the ratios of △[PFCAs] to their concentration before oxidation (△[PFCA]/[PFCA]before oxidation) indicated obvious spatial variations in the seawater and STP effluents. The higher levels of △[PFCAC4-C12] and the lower ratios of ∑△[PFCAC4-C12]/∑[PFAA]before oxidation were observed in the STP effluents, which implied that precursors might be decomposed during the sewage treatment process. These results suggested the STP effluents might have an important effect on the PFAAs levels of seawater.


Assuntos
Monitoramento Ambiental/métodos , Fluorcarbonetos/análise , Água do Mar/química , Sulfonamidas/análise , Poluentes Químicos da Água/análise , Ácidos Carboxílicos/análise , China , Cidades , Oxirredução , Análise Espacial
10.
Chemosphere ; 238: 124575, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31446274

RESUMO

Significance of surface and ground water contamination by synthetic organic compounds has been pointed out in a very high number of papers worldwide, as well as the need of application of treatment technologies capable to assure their complete removal. Among these processes, the electrochemical advanced oxidation is an interesting option, especially when irradiated with UVC light (photo-electrochemical, P-EC) to promote homolysis of electrogenerated oxidants. In this work, the herbicide glyphosate (GLP) was used as model compound and it was electrochemically treated under UVC irradiation in the presence of NaCl and using a DSA® and BDD anodes. Total organic carbon concentration was measured throughout the electrolysis, as well as the concentration of short chain carboxylic acids and inorganic ions (NO3-, PO43-,ClO-, ClO3- and ClO4-). The synergism of the P-EC was more pronounced when using a DSA® electrode, which led to complete GLP mineralization in 1 h (0.52 A h L-1), as also confirmed by the stoichiometric formation of NO3- and PO43- ions, with an energy consumption as low as 1.25 kW h g-1. Unexpectedly, the concentration evolution of oxyhalides for the P-EC process using both anodes, especially for DSA® at 10 mA cm-2, showed the production of ClO3-, whereas detection of ClO4- species was only found when using BDD at 100 mA cm-2 for the electrochemical process. Finally, small amounts of carboxylic acids were detected, including dichloroacetic acid, especially when using a BDD electrode.


Assuntos
Técnicas Eletroquímicas/métodos , Glicina/análogos & derivados , Água Subterrânea/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Purificação da Água/métodos , Ácidos Carboxílicos/análise , Diamante/química , Eletrodos , Glicina/análise , Oxidantes/química , Oxirredução , Raios Ultravioleta
11.
Drug Test Anal ; 12(2): 230-238, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31655024

RESUMO

Hair analysis has become a valuable tool in forensic toxicology to assess drug or alcohol abstinence. Yet, hair adulteration by cosmetic products presents a major challenge for forensic hair analysis. Oxidative treatments, e.g. bleaching, may lead to analyte loss and thereby to false negative results. Currently, the eumelanin degradation product 1H-pyrrole-2,3,5-tricarboxylic acid (PTCA) serves as a marker for oxidative hair treatment, but requires the definition of cut-off values. To investigate further eumelanin degradation products as markers for oxidative hair treatment, hair samples with and without in vitro bleaching (hydrogen peroxide (H2 O2 ) concentrations 1.9% up to 12%; incubation times 15 min, 30 min, 60 min) were analyzed by liquid chromatography coupled to high-resolution time of flight mass spectrometry (HPLC-HRMS). The distribution of eumelanin degradation products along the hair shaft was investigated for routine applicability after segmentation of cosmetically untreated hair samples and authentically treated hair samples. The signals of the eumelanin degradation products PTCA, 1H-pyrrole-2,3,4-tricarboxylic acid (isoPTCA), and 1H-pyrrole-2,3,4,5-tetracarboxylic acid (PTeCA) were found to be significantly elevated after in vitro bleaching already with low H2 O2 concentrations and after short incubation times. In contrast to PTCA and isoPTCA, PTeCA was not detectable in cosmetically untreated segments up to 12 cm from hair root and was only formed through the oxidation process. The results of the study show that the detection of PTeCA within the proximal 3 to 6 cm segment can be applied to reliably detect hair adulteration attempts through hair bleaching.


Assuntos
Ácidos Carboxílicos/análise , Cabelo/química , Peróxido de Hidrogênio/química , Pirróis/análise , Cromatografia Líquida de Alta Pressão , Contaminação de Medicamentos , Toxicologia Forense , Humanos , Melaninas/análise , Oxirredução
12.
Environ Pollut ; 257: 113594, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31753633

RESUMO

Soils in urban and industrial areas, especially in larger metropolitan areas such as the Ruhr area, Germany, are commonly characterized by severe anthropogenic overprinting due to urbanization processes including land development measures. Such urban soils often contain various anthropogenic substrate admixtures, like ash, coal, tailings, building rubble, industrial waste materials, as well as urban dust, soot, fly ash, and others. These admixtures often carry higher contents of pollutants such as polycyclic aromatic hydrocarbons (PAH). Whereas elevated PAH concentrations are commonly attributed to non-point pyrogenic carbon sources like soot and particulate matter, petrogenic PAH sources are still largely neglected in this context. In this study, an extended sample set of 62 samples of PAH source materials and urban soils containing anthropogenic substrate components was investigated by combining extended PAH analysis of 59 PAH, alkylated PAH distributions and benzene polycarboxylic acid (BPCA) analysis with regard to petrogenic and pyrogenic PAH source identification. For more reliability of source apportionment by a more integrative signal, the alkylated PAH distributions of different PAH groups were combined according to their degrees of alkylation. Based on this combination, a new PAH alkylation index (ΣC0/(ΣC0+ΣC2)) was derived, which considers, in contrast to commonly used single PAH ratios, a series of non-alkylated and alkylated PAH. By comparison of this PAH alkylation index with the degree of aromatic condensation a new robust and economic method for identifying petrogenic, pyrogenic and mixed PAH sources within soil samples and sediments was developed. It is shown that coal and coal ash particles are a not negligible PAH source in urban soils of mining-dominated regions and can make up a large proportion of the anthropogenic substrate components encountered. Further analyses of samples with defined levels of petrogenic and pyrogenic PAH are necessary to finally evaluate the usefulness of this proposed new PAH-BPCA approach.


Assuntos
Monitoramento Ambiental , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes do Solo/análise , Solo/química , Benzeno/análise , Carbono/análise , Ácidos Carboxílicos/análise , Carvão Mineral/análise , Poeira/análise , Alemanha , Reprodutibilidade dos Testes , Fuligem/análise , Urbanização
13.
Food Chem ; 310: 125799, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31711809

RESUMO

In this study we explore the effects of multi-colour LED lighting spectrum on nutritive primary metabolites in green ('Lobjoits green cos') and red ('Red cos') leaf lettuce (Lactuca sativa L.), cultivated in controlled environment. The basal lighting, consisting of blue 455 nm, red 627 and 660 nm and far red 735 nm LEDs, was supplemented with UV-A 380 nm, green 510 nm, yellow 595 nm or orange 622 nm LED wavelengths at total photosynthetic photon flux density of 300 µmol m-2 s-1. Supplemental lighting colours did not affect lettuce growth; however had distinct impact on nitrite, amino acid, organic acid, and soluble sugar contents. Orange, green and UV-A light had differential effects on red and green leaf lettuce metabolism and interplay with nutritional value and safety of lettuce production. The metabolic response was cultivar specific; however green light had reasonable impact on the contents of nutritive primary metabolites in red and green leaf lettuce.


Assuntos
Aminoácidos/metabolismo , Ácidos Carboxílicos/metabolismo , Alface/química , Alface/fisiologia , Nitratos/metabolismo , Aminoácidos/análise , Ácidos Carboxílicos/análise , Ambiente Controlado , Iluminação , Nitratos/análise , Nitritos/metabolismo , Fotossíntese , Pigmentação , Açúcares/análise , Açúcares/metabolismo , Raios Ultravioleta
14.
J Chromatogr A ; 1614: 460710, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31784082

RESUMO

To monitor the existing and emerging halogenated carboxylic acids (HCAs) in drinking water, a sensitive and rapid ultra-high performance liquid chromatography-quadrupole orbitrap high-resolution mass spectrometry method for simultaneous target quantification of 10 haloacetic acids (HAAs) and semi-target screening of 19 HCAs was developed. After filtration, drinking water samples were injected into the instrument. HCAs were separated on an HSS T3 column and detected by a type of non-target scan in the electrospray ionization negative mode. For target quantification of 10 HAAs, good linearity was obtained and the correlation coefficients were higher than 0.995. The limits of detection were in the range of 0.050-2.0 µg/L. The recoveries were in the range of 89.7%-108%, 83.4%-121%, 77.1%-116% and 80.2%-104% at levels of 2.5, 5.0, 10 and 20 µg/L, respectively, with relative standard deviations of 1.26%-16.9%. For semi-target screening of 19 HCAs, several criteria including accurate m/z, predicted retention time, deduced fragment ions and simulated isotope pattern were used for identification. The method was applied to analyzing 41 drinking water samples successfully. Five HAAs were detected by target quantification, with dichloroacetic acid and trichloroacetic acid exceeding the limits suggested by the U.S. Environmental Protection Agency and the World Health Organization. Eight HCAs were preliminary identified by semi-target screening, and three of them were further confirmed with reference standards purchased later.


Assuntos
Ácidos Carboxílicos/análise , Cromatografia Líquida de Alta Pressão/métodos , Água Potável/química , Espectrometria de Massas/métodos , Halogenação , Limite de Detecção
15.
World J Gastroenterol ; 25(43): 6416-6429, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31798278

RESUMO

BACKGROUND: Fecal metabolites are associated with gut visceral sensitivity, mucosal immune function and intestinal barrier function, all of which have critical roles in the pathogenesis of irritable bowel syndrome (IBS). However, the metabolic profile and pathophysiology of IBS are still unclear. We hypothesized that altered profiles of fecal metabolites might be involved in the pathogenesis of IBS with predominant diarrhea (IBS-D). AIM: To investigate the fecal metabolite composition and the role of metabolites in IBS-D pathophysiology. METHODS: Thirty IBS-D patients and 15 age- and sex-matched healthy controls (HCs) underwent clinical and psychological assessments, including the IBS Symptom Severity System (IBS-SSS), an Italian modified version of the Bowel Disease Questionnaire, the Bristol Stool Form Scale (BSFS), the Hospital Anxiety and Depression Scale, and the Visceral Sensitivity Index. Visceral sensitivity to rectal distension was tested using high-resolution manometry system by the same investigator. Fecal metabolites, including amino acids and organic acids, were measured by targeted metabolomics approaches. Correlation analyses between these parameters were performed. RESULTS: The patients presented with increased stool water content, more psychological symptoms and increased visceral hypersensitivity compared with the controls. In fecal metabolites, His [IBS-D: 0.0642 (0.0388, 0.1484), HC: 0.2636 (0.0780, 0.3966), P = 0.012], Ala [IBS-D: 0.5095 (0.2826, 0.9183), HC: 1.0118 (0.6135, 1.4335), P = 0.041], Tyr [IBS-D: 0.1024 (0.0173, 0.4527), HC: 0.5665 (0.2436, 1.3447), P = 0.018], Phe [IBS-D: 0.1511 (0.0775, 0.3248), HC: 0.3967 (0.1388, 0.7550), P = 0.028], and Trp [IBS-D: 0.0323 (0.0001, 0.0826), HC: 0.0834 (0.0170, 0.1759), P = 0.046] were decreased in IBS-D patients, but isohexanoate [IBS-D: 0.0127 (0.0060, 0.0246), HC: 0.0070 (0.0023, 0.0106), P = 0.028] was significantly increased. Only Tyr was mildly correlated with BSFS scores in all subjects (r = -0.347, P = 0.019). A possible potential biomarker panel was identified to correlate with IBS-SSS score (R 2 Adjusted = 0.693, P < 0.001). In this regression model, the levels of Tyr, Val, hexanoate, fumarate, and pyruvate were significantly associated with the symptom severity of IBS-D. Furthermore, visceral sensation, including abdominal pain and visceral hypersensitivity, was correlated with isovalerate, valerate and isohexanoate. CONCLUSION: Altered profiles of fecal metabolites may be one of the origins or exacerbating factors of symptoms in IBS-D via increasing visceral sensitivity.


Assuntos
Dor Abdominal/etiologia , Ácidos Carboxílicos/metabolismo , Síndrome do Intestino Irritável/metabolismo , Dor Abdominal/metabolismo , Adulto , Ácidos Carboxílicos/análise , Estudos de Casos e Controles , Fezes/química , Feminino , Humanos , Síndrome do Intestino Irritável/complicações , Masculino , Índice de Gravidade de Doença
16.
Artigo em Inglês | MEDLINE | ID: mdl-31877809

RESUMO

The reliable quantification of perfluoroalkyl carboxylic acids (PFCAs) in environmental samples like surface water by using gas chromatography (GC) remains challenging because the polar PFCAs call for derivatization before injection and problems involving the integration of sample pretreatment and derivatization procedures. Here we proposed a cost-effective method for the GC based determination of C4-C12 PFCAs in surface water samples by integrating solid phase extraction and PFCAs anilide derivatization. First, we assessed the performance of different PFCAs derivatization methods, namely esterification and amidation. Esterification was unable to derivatize C4-C6 PFCAs. On the contrary, amidation procedures by using 2,4-difluoroaniline (DFA) and N,N'-dicyclohexylcarbodiimide (DCC) could successfully transform all the PFCA analogs to produce anilide derivatives, which could be easily detected by GC. Then the reaction conditions in the amidation approach were further optimized by using orthogonal design experiments. After optimizing the instrumental parameters of GC, the limits of detection (LOD) of this derivatization method were determined to be 1.14-6.32 µg L-1. Finally, in order to establish an intact method for the quantification of PFCAs in surface water samples, solid phase extraction (SPE) was used for extraction and cleanup, which was further integrated with the subsequent amidation process. The SPE-amidation-GC method was validated for application, with good accuracy and precision reflected by the PFCAs recoveries and derivatization of triplicates. The method reported here could provide a promising and cost-effective alternative for the simultaneous determination of C4-C12 PFCAs in environmental water samples.


Assuntos
Ácidos Carboxílicos/análise , Cromatografia Gasosa/métodos , Monitoramento Ambiental/métodos , Fluorcarbonetos/análise , Monitoramento Ambiental/economia
17.
J Vis Exp ; (152)2019 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-31680684

RESUMO

Caged compounds enable the photo-mediated manipulation of the cell physiology with high spatiotemporal resolution. However, the limited structural diversity of currently available caging groups and the difficulties in synthetic modification without sacrificing their photolysis efficiencies are obstacles to expanding the repertoire of caged compounds for live cell applications. As the chemical modification of coumarin-type photo-caging groups is a promising approach for the preparation of caged compounds with diverse physical and chemical properties, we report a method for the synthesis of clickable caged compounds that can be modified easily with various functional units via the copper(I)-catalyzed Huisgen cyclization. The modular platform molecule contains a (6-bromo-7-hydroxycoumarin-4-yl)methyl (Bhc) group as a photo-caging group, which exhibits a high photolysis efficiency compared to those of the conventional 2-nitrobenzyls. General procedures for the preparation of clickable caged compounds containing amines, alcohols, and carboxylates are presented. Additional properties such as the water solubility and cell targeting ability can be readily incorporated into clickable caged compounds. Furthermore, the physical and photochemical properties, including the photolysis quantum yield, were measured and were found to be superior to those of the corresponding Bhc caged compounds. The described protocol could therefore be considered a potential solution for the lack of structural diversity in the available caged compounds.


Assuntos
Cumarínicos/síntese química , Imagem Óptica/métodos , Processos Fotoquímicos , Fotólise , Álcoois/análise , Álcoois/síntese química , Animais , Células CHO , Ácidos Carboxílicos/análise , Ácidos Carboxílicos/síntese química , Cumarínicos/análise , Cricetinae , Cricetulus , Solubilidade
18.
Environ Sci Process Impacts ; 21(12): 2109-2117, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31656961

RESUMO

A large quantity of emerging contaminants are ionizable, and the ionized compounds display different adsorption behaviors than their neutral counterparts. In particular, a strong intermolecular force, negative charge assisted hydrogen bonding ((-)CAHB), was recently identified, which explains the unusually strong adsorption of negatively charged compounds on carbon nanotubes with oxygen-containing functional groups. However, most previous studies only probed molecules with one benzene ring. The adsorption of ionizable compounds with more than one benzene ring and additional functional groups has not been examined. This study investigated the effect of surface functionalization, molecular size and structure of six aromatic carboxylic acids on their adsorption on multi-walled carbon nanotubes (MWNTs) in batch reactors. In addition, the short-range interactions of the neutral acids with MWNTs were calculated to evaluate the effect of aromaticity and bulkiness. Hydrophobicity and electrostatic interactions dominate the intermolecular forces between ionized contaminants and MWNT surfaces. pH dependent octanol/water partitioning coefficient (Dow) is a more precise indicator of the adsorption of ionizable compounds on MWNTs. (-)CAHB is a significant force only for compounds with one benzene ring. Hydroxyl and carboxyl functional groups displayed similar capacity to form (-)CAHB, as indicated by the release of hydroxide ions.


Assuntos
Ácidos Carboxílicos/química , Poluentes Ambientais/química , Hidrocarbonetos Aromáticos/química , Modelos Teóricos , Nanotubos de Carbono/química , Adsorção , Ácidos Carboxílicos/análise , Poluentes Ambientais/análise , Hidrocarbonetos Aromáticos/análise , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Hidróxidos/análise , Hidróxidos/química , Estrutura Molecular , Propriedades de Superfície
19.
Analyst ; 144(23): 6981-6988, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31631209

RESUMO

Triterpenoids, as an important family of plant secondary metabolites, have important biological activities associated with health and disease prevention. In this work, we proposed a HPLC-MS method for profiling multiple groups of triterpenoid acids and triterpenoid esters differing only in one position of the hydroxyl or methyl group in O. fragrans fruits. A total of thirty-one compounds were identified, and twenty-seven components were discovered in O. fragrans fruits for the first time. The HPLC-MS profiling method was applied in the analysis of the triterpenoids of O. fragrans flowers, and the time courses of triterpenoids of O. fragrans fruits.


Assuntos
Ácidos Carboxílicos/análise , Ésteres/análise , Frutas/química , Oleaceae/química , Triterpenos/análise , Ácidos Carboxílicos/química , Cromatografia Líquida de Alta Pressão/métodos , Ésteres/química , Flores/química , Isomerismo , Espectrometria de Massas/métodos , Triterpenos/química
20.
Environ Sci Process Impacts ; 21(11): 1864-1874, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31524218

RESUMO

The present work examined the trophic transfer of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in a typical urban river (Orge River, near Paris, France), and aimed to investigate the potential contribution of precursors to the biomagnification of perfluoroalkyl acids (PFAAs). Sixteen PFAAs, twelve of their precursors (pre-PFAAstargeted) and two fluorinated alternatives to long-chain PFASs were analyzed in water, sediments and biota (including biofilm, invertebrates and fish). Twenty two compounds were detected in biological samples (2.0-147 ng g-1 wet weight), perfluorooctane sulfonate (PFOS) and C12-C14 perfluoroalkyl carboxylates (PFCAs) being predominant while ∑pre-PFAAstargeted contributed to 1-18% of ∑PFASs. Trophic magnification factors (TMFs) were >1 (i.e. denoting biomagnification) for C9-C14 PFCAs, C7-C10 perfluoroalkyl sulfonates (PFSAs) and several pre-PFAAs (e.g. 8 : 2 and 10 : 2 fluorotelomer sulfonates). The significant decrease in ∑pre-PFCAs/∑PFCAs concentration ratio with trophic level suggested a likely contribution of selected precursors to the biomagnification of PFCAs through biotransformation, while this was less obvious for PFOS. The total oxidizable precursor assay, applied for the first time to sediment and biota, revealed the presence of substantial proportions of extractable unknown pre-PFAAs in all samples (i.e. 15-80% of ∑PFASs upon oxidation). This proportion significantly decreased from sediments to invertebrates and fish, thereby pointing to the biotransformation of unattributed pre-PFAAs in the trophic web, which likely contributes to the biomagnification of some PFAAs (i.e. C9-C12 PFCAs and C7-C10 PFSAs).


Assuntos
Ácidos Alcanossulfônicos/análise , Ácidos Carboxílicos/análise , Monitoramento Ambiental/métodos , Fluorcarbonetos/análise , Rios/química , Poluentes Químicos da Água/análise , Ácidos Alcanossulfônicos/metabolismo , Animais , Bioacumulação , Biofilmes , Ácidos Carboxílicos/metabolismo , Peixes/metabolismo , Fluorcarbonetos/metabolismo , Cadeia Alimentar , França , Invertebrados/metabolismo , Poluentes Químicos da Água/metabolismo
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