RESUMO
Naphthenic acids (NAs) are naturally occurring organic acids in petroleum and are found in waste waters generated during oil production (produced water, PW). Profiling this class of compounds is important due to flow assurance during oil exploration. Compositional analysis of PW is also relevant for waste treatment to reduce negative impacts on the environment. Here, comprehensive two-dimensional gas chromatography coupled with high-resolution mass spectrometry (GC×GC-HRMS) was applied as an ideal platform for qualitative analysis of NAs by combining the high peak capacity of the composite system with automated scripts for group-type identification based on accurate mass measurements and fragmentation patterns. To achieve high-throughput profiling of NAs in PW samples, direct-immersion solid phase microextraction (DI-SPME) was selected for extraction, derivatization and preconcentration. A fully automated DI-SPME method was developed to combine extraction, fiber rinsing and drying, and on-fiber derivatization with N-methyl-Ntert-butyldimethylsilyltrifluoroacetamide (MTBSTFA). Data processing was based on filtering scripts using the Computer Language for Identifying Chemicals (CLIC). The method successfully identified up to 94 NAs comprising carbon numbers between 6 and 18 and hydrogen deficiency values ranging from 0 to -4. The proposed method demonstrated wider extraction coverage compared to traditional liquid-liquid extraction (LLE) - a critical factor for petroleomic investigations. The method developed also enabled quantitative analysis, exhibiting detection limits of 0.5 ng L-1 and relative standard deviation (RSD) at a concentration of NAs of 30 µg L-1 ranging from 4.5 to 25.0%.
Assuntos
Microextração em Fase Sólida , Poluentes Químicos da Água , Imersão , Cromatografia Gasosa-Espectrometria de Massas/métodos , Ácidos Carboxílicos/análise , Poluentes Químicos da Água/análiseRESUMO
This work describes the surface coating of wooden toothpicks with amino groups (NH2) for electrospray ionization mass spectrometry (MS) analysis of naphthenic acids (NAs) in produced water samples and crude oil fractions. NH2 was introduced into the cellulosic material through a silanization reaction using aminopropyltriethoxysilane. An NH2-modified toothpick was inserted into the analyte extraction sample and was subsequently used as an electrospray emitter for MS analysis. The extraction conditions were optimized by analyzing NAs (benzoic acid, 1-naphthoic acid, decanoic acid, 3,5-dimethyladamantane-1-carboxylic acid, and 3,5-dimethyladamantane-1-acetic acid) in pure water, and the best condition was using 5 min of extraction time with the samples under agitation. Modified and unmodified wooden toothpicks were compared, and the intensities of all NAs were higher when using the modified substrates than when using the unmodified ones. Limit of detection (LOD), limit of quantification (LOQ), linearity, precision, and recovery were determined by analyzing decanoic acid in seawater samples. The LOD and LOQ were 2 and 5 µg mL-1, respectively, and a linear correlation (R2 = 0.9927) was obtained with concentrations ranging from 5 to 250 µg mL-1. Precision values ranged from 6 to 13% and recoveries from 89 to 106%. The technique was also employed to analyze three produced water samples, in which decanoic acid was semi-quantified, and the concentrations ranged from 10 to 13 µg mL-1. High abundances of acidic compounds of class O2 with DBEs (double bond equivalents) ranging from 1 to 3 and carbon numbers going from 8 to 12 were detected in the produced water samples. The results suggest that the modification of wooden toothpicks with NH2 might offer a significant advancement in the knowledge of cheap substrates that can improve the sensitivity of analysis of NAs in water samples.
Assuntos
Petróleo , Espectrometria de Massas por Ionização por Electrospray , Ácidos Carboxílicos/análise , Ácidos Carboxílicos/química , Espectrometria de Massas por Ionização por Electrospray/métodos , ÁguaRESUMO
Propolis comprises a complex resinous product composed of plant's parts or exudates, pollen, bee wax, and enzymes. Brazilian brown propolis from Araucaria sp displays several biological activities. Considering the lack of validated analytical methods for its analysis, we are reporting the development of a validated high-performance liquid chromatography with photodiode array detector method to analyze Araucaria brown propolis. The crude propolis were extracted and chromatographed, furnishing six main diterpenes. The isolated standards were used to draw the analytical curves, allowing the studies of selectivity, precision, accuracy, recovery, robustness, the determination of limits of detection and limits of quantification. The mobile phase consisted of 0.1% acetic acid in water and acetonitrile, using an octadecylsilane column, 1 mL/min flow rate and detection at 200 or 241 nm. Relative standard deviation values obtained for intra-day and inter-day precision were lower than 4% for all diterpenes. From the five parameters for robustness, wavelength detection and flow rate were the critical ones. Limits of detection and quantification ranged from 0.808 to 10.359 µg/mL and from 2.448 to 31.392 µg/mL, respectively. The recoveries were between 105.03 and 108.13%, with relative standard deviation values around 5.0%. The developed method is precise, sensitive, and reliable for analyzing Araucaria brown propolis.
Assuntos
Araucaria/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Diterpenos/análise , Própole/análise , Abietanos/análise , Brasil , Ácidos Carboxílicos/análise , Técnicas de Química Analítica , Limite de Detecção , Modelos Lineares , Reprodutibilidade dos Testes , Tetra-Hidronaftalenos/análiseRESUMO
Volatile and non-volatile compounds in coffee directly affect the beverage's quality. This study aimed to demonstrate how the organic acids and volatile profiles were impacted by coffee fermentation using four starter cultures (Meyerozyma caribbica (CCMA 0198), Saccharomyces cerevisiae (CCMA 0543), Candida parapsilosis (CCMA0544), and Torulaspora delbrueckii (CCMA 0684)) inoculated in two varieties of coffee (Bourbon Amarelo and Canário Amarelo) using natural and pulped natural processing methods and sensory perception. Real-time PCR (qPCR) was used to verify the dynamic behavior of yeast populations. Organic acids were detected using high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) was used to detected volatile compounds. Sensory analysis was performed on the roasted coffee. Citric, malic, succinic, lactic, oxalic, isobutyric, and propionic acids and 105 volatile compounds were detected. At the beginning of fermentation, treatments with natural processing presented higher number of volatiles compounds. After fermentation, the main compounds groups were acids, alcohols, and aldehydes. The perception of sensory attribute (fruity, nutty, cocoa) varied with the coffee variety, type of processing, and type of inoculum. The use of yeasts is an alternative for sensorial differentiation of coffee variety Canário Amarelo and Bourbon Amarelo. The stainless-steel containers showed good results for coffee fermentation.
Assuntos
Ácidos Carboxílicos/análise , Café/química , Fermentação , Manipulação de Alimentos/métodos , Qualidade dos Alimentos , Fermento Seco/metabolismo , Candida parapsilosis , Ácidos Carboxílicos/química , Cromatografia Líquida de Alta Pressão , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Reação em Cadeia da Polimerase , Saccharomyces cerevisiae , Saccharomycetales , TorulasporaRESUMO
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 1â¯h (0.52â¯Aâ¯h L-1), as also confirmed by the stoichiometric formation of NO3- and PO43- ions, with an energy consumption as low as 1.25â¯kWâ¯h g-1. Unexpectedly, the concentration evolution of oxyhalides for the P-EC process using both anodes, especially for DSA® at 10â¯mAâ¯cm-2, showed the production of ClO3-, whereas detection of ClO4- species was only found when using BDD at 100â¯mAâ¯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 , GlifosatoRESUMO
A Fenton like advanced oxidation process (AOP) employing scrap zerovalent iron (SZVI) and hydrogen peroxide (H2O2) was studied for industrial textile wastewater treatment from a textile manufacturing plant located at Medellín, Colombia (South America). The wastewater effluent studied contains a mixture of organic compounds resistant to conventional treatments. The effect of initial pH and SZVI concentration and H2O2 concentration were studied by a response surface methodology (RSM) Box-Behnken design of experiment (BBD). The combined SZVI/H2O2 process led to reductions of 95% color, 76% of chemical oxygen demand (COD) and 71% of total organic carbon (TOC) at optimal operating conditions of pHâ¯=â¯3, SZVIâ¯=â¯2000â¯mg/L and [H2O2]â¯=â¯24.5â¯mM. Molecular weight distribution measurement (MWD), ultraviolet-visible (UV-Vis) spectroscopy, HPLC, biodegradability and toxicity were used to characterize the pollutants after the treatment process finding that the resulting effluent was polluted mostly by low molecular weight carboxylic acids. A remarkable biodegradability enhancement of the effluent was evidenced by a BOD5/COD ratio increase from 0.22 to 0.4; also, the SZVI/H2O2 process successfully reduced the toxicity from 60% to 20% of dead A. Salina crustaceans.
Assuntos
Ácidos Carboxílicos/análise , Peróxido de Hidrogênio/química , Ferro/química , Indústria Têxtil , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Biodegradação Ambiental , Análise da Demanda Biológica de Oxigênio , Ácidos Carboxílicos/toxicidade , Colômbia , Concentração de Íons de Hidrogênio , Modelos Teóricos , Oxirredução , Poluentes Químicos da Água/toxicidadeRESUMO
Approximately 90% of the chili peppers consumed in the world are harvested in Mexico. The present article describes the untargeted 1H NMR-based metabolomic profiling of 11 cultivars of Capsicum annuum species which are routinely consumed worldwide. The metabolomic fingerprinting detected via 1H NMR contained 44 metabolites including sugars, amino acids, organic acids, polyphenolic acids and alcohols which were identified by comparison with the literature data, with Chenomx database and by 2D NMR. Statistical approaches based on principal component analysis (PCA) and linear discriminant analysis (LDA) were used to classify the Capsicum annuum cultivars according to their metabolite profile. LDA revealed metabolomic differences and similarities among Capsicum annuum cultivars, whereas hierarchical cluster analysis (HCA) significantly separated the cultivars according to the phylogenetic trees obtained. Substantial endogenous levels of free amino acids and carbohydrates were detected in all the studied cultivars but interestingly, Capsicum annuum cv. mirasol and C. annuum cv. chilaca contained almost three-fold more endogenous levels of vitamin C than the other cultivars. Considering that this antioxidant was found in crude aqueous extracts, its abundance could be directly proportional to its bioavailability for human nutrition. The results suggest that 1H NMR is an effective method to determine differences among cultivars of the Capsicum annuum species.
Assuntos
Capsicum/química , Capsicum/metabolismo , Metaboloma/fisiologia , Aminoácidos/análise , Ácidos Carboxílicos/análise , Análise Discriminante , Metabolômica , México , Ressonância Magnética Nuclear Biomolecular , Análise de Componente Principal , Açúcares/análiseRESUMO
Molecular acid/base properties have a significant influence on membrane permeation, metabolism, absorption, and affinity for biological targets. In particular, ionizable groups are critical in the strength of target-molecule interactions, pharmacokinetics, and toxicity. In this study, we estimated the acid/base properties of the food chemicals from FooDB, a public compound collection with more than 22,000 compounds. It was found that the food chemicals have 40.9 % of neutral compounds, which is twice as many as that found in approved drugs. The most common functional groups among the acid groups in the food chemicals were phenols (16.1 %), phosphates (17.3 %), and carboxylates (17.3 %) while the single-base-containing compounds were of less interest as they accounted for just 5.5 %. To the best of our knowledge, this is the first systematic acid/base profiling of food chemicals and it is part of a continued effort to profile food chemicals for their broad interest in several areas such as nutrition and the food industry in general.
Assuntos
Ácidos Carboxílicos/análise , Bases de Dados de Produtos Farmacêuticos , Contaminação de Alimentos/análise , Fenóis/análise , Fosfatos/análise , Concentração de Íons de HidrogênioRESUMO
A sensitive, fast, and inexpensive square wave voltammetric method using a cobalt phthalocyanine modified carbon paste electrode was developed for simultaneous determination of citric, lactic, malic and tartaric acids in fruit juices. To overcome the strong overlap of voltammetric signals caused by calibrated and uncalibrated constituents, multivariate curve resolution with alternating least squares (MCR-ALS) was used. Data were previous treated for correction of baseline and potential shift. The MCR-ALS calibration models were constructed and evaluated using a validation set obtained from a Taguchi design. The values predicted by the optimized MCR-ALS models were unbiased and no statistically significant difference was observed between proposed and reference methods, applying the paired t-test at a confidence level of 95%. As far as the authors know, a voltammetric method that simultaneously determines four organic acids in complex samples such as fruit juices without any previous pretreatment has not yet been reported in the literature.
Assuntos
Ácidos Carboxílicos/análise , Técnicas Eletroquímicas/métodos , Eletrodos , Sucos de Frutas e Vegetais/análise , Calibragem , Ácido Cítrico/análise , Indóis , Ácido Láctico/análise , Malatos/análise , Compostos Organometálicos , Tartaratos/análiseRESUMO
N-Ethyl perfluorooctane sulfonamide (EtFOSA) is a perfluorooctane sulfonate (PFOS) precursor and the active ingredient in sulfluramid, a pesticide which is used extensively in Brazil for management of leaf cutting ants. Here we investigate the occurrence of EtFOSA, PFOS, and other per- and polyfluoroalkyl substances (PFASs) in soil, eucalyptus leaves, water (ground, riverine, and coastal (estuarine/marine)) and coastal sediment from an agricultural region of Bahia State, Brazil. This area contains a larger number of eucalyptus plantations where sulfluramid is suspected to be applied. Soil, leaves, and coastal water (marine/estuarine) contained ∑PFAS concentrations of up to 5400â¯pgâ¯g-1, 979â¯pgâ¯g-1, and 1020â¯pgâ¯L-1, respectively, with PFAS profiles generally dominated by PFOS and perfluorooctane sulfonamide (FOSA). Coastal sediment contained ∑PFAS concentrations of up to 198 pgâ¯g-1, with PFOS, FOSA, and perfluorooctanoic acid (PFOA) being the most frequently observed PFASs. These substances are all potential EtFOSA transformation products, pointing to sulfluramid as a possible source. In riverine water, ∑PFAS concentrations of up to 8930â¯pgâ¯L-1 were observed. PFOS and PFOA were detected in all river water samples. Groundwater also exhibited PFAS contamination (5730â¯pgâ¯L-1 ∑PFASs), likely from sulfluramid use. The observation of other PFASs (e.g. perfluorobutanoic acid) in freshwater suggests that other PFAS sources (in addition to sulfluramid) may be important in this region. Overall, these data support the hypothesis that sulfluramid use contributes to the occurrence of PFASs in the Brazilian environment.