ORCID Profile
0000-0002-5759-612X
Current Organisation
Universidade Federal de Minas Gerais
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Publisher: Sociedade Brasileira de Quimica (SBQ)
Date: 2019
Publisher: Elsevier BV
Date: 11-2019
Publisher: Elsevier BV
Date: 07-2013
DOI: 10.1016/J.JCHROMB.2013.05.014
Abstract: The determination of the concentrations of l-amino acids in cerebrospinal fluid (CSF) has been used to gain biochemical insight into central nervous system disorders. This paper describes a microwave-assisted derivatization (MAD) method using N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) as a derivatizing agent for determining the concentrations of l-amino acids in human CSF by gas chromatography with mass spectrometry (GC/MS). The experimental design used to optimize the conditions showed that the optimal derivatization time was 3min with a microwave power of 210W. The method showed good performance for the validation parameters. The sensitivity was very good, with limits of detection (LODs) ranging from 0.01μmolL(-1) to 4.24μmolL(-1) and limits of quantification (LOQs) ranging from 0.02 to 7.07μmolL(-1). The precision, measured using the relative standard deviation (RSD), ranged from 4.12 to 15.59% for intra-day analyses and from 6.36 to 18.71% for inter-day analyses. The coefficients of determination (R(2)) were above 0.990 for all amino acids. The optimized and validated method was applied to the determination of amino acid concentrations in human CSF.
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.CHROMA.2018.11.046
Abstract: Polycyclic aromatic hydrocarbons (PAHs) are food contaminants besides, their oxygenated (oxy-PAHs) and nitrated (nitro-PAHs) derivatives have also been detected in some foods. This is worrying because these derivatives may be more toxic than PAHs. This study presents a new method for the determination of PAHs and their oxygenated and nitrated derivatives in coffee brew. The analytes were extracted by cold fiber solid phase microextraction (CF-SPME) with analysis by gas chromatography/mass spectrometry. The developed method presented good precision with intra-assay and inter-assay, ranged from 4.5 to 16.4%, and from 9.8 to 19.8%, respectively. Recovery ranged from 82.1 to96.3% and linearity showed good adjustment presenting determination coefficients (R
Publisher: Springer Science and Business Media LLC
Date: 15-02-2017
DOI: 10.1007/S00216-017-0226-9
Abstract: Acrolein is a pollutant released daily to the indoor environment from different sources. The present study reports the development of a simple and sensitive cold fiber solid phase microextraction s ling method for the determination of acrolein in exhaled air and indoor air by gas chromatography mass spectrometry. O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine was used as derivatizing agent supported on a 65-μm polydimethylsiloxane- inylbenzene SPME fiber. An acrolein permeation tube at 326.25 ng min
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.TALANTA.2017.02.054
Abstract: This article describes a simple, efficient, and versatile magnetic carbon nanotubes (MCNT) method for s ling and pre-concentration of pesticides in environmental water s les. The multi-walled magnetic carbon nanotubes were obtained by chemical deposition vapor (CVD) process. The MCNTs structures are formed of hydrophobic and hydrophilic fractions that provide great dispersion at any water matrix allowing simultaneously a high efficiency of pesticides sorption. Following the extraction, analytes were desorbed with minor amounts of solvent and analyzed by gas chromatography coupled mass spectrometry (GC/MS). The parameters amount of MCNTs used to extraction, desorption time, and desorption temperature were optimized. The method showed good linearity with determination coefficients between 0.9040 and 0.9733. The limits of detection and quantification were ranged between 0.51 and 2.29µgL
Publisher: Elsevier BV
Date: 12-2023
Publisher: Hindawi Limited
Date: 20-01-2019
DOI: 10.1155/2019/8480468
Abstract: Ischemic stroke is a neurovascular disorder caused by reduced or blockage of blood flow to the brain, which may permanently affect motor and cognitive abilities. The diagnostic of stroke is performed using imaging technologies, clinical evaluation, and neuropsychological protocols, but no blood test is available yet. In this work, we analyzed amino acid concentrations in blood plasma from poststroke patients in order to identify differences that could characterize the stroke etiology. Plasma concentrations of sixteen amino acids from patients with chronic ischemic stroke (n = 73) and the control group (n = 16) were determined using gas chromatography coupled to mass spectrometry (GC-MS). The concentration data was processed by Partial Least Squares-Discriminant Analysis (PLS-DA) to classify patients with stroke and control. The amino acid analysis generated a first model able to discriminate ischemic stroke patients from control group. Proline was the most important amino acid for classification of the stroke s les in PLS-DA, followed by lysine, phenylalanine, leucine, and glycine, and while higher levels of methionine and alanine were mostly related to the control s les. The second model was able to discriminate the stroke subtypes like atherothrombotic etiology from cardioembolic and lacunar etiologies, with lysine, leucine, and cysteine plasmatic concentrations being the most important metabolites. Our results suggest an amino acid biosignature for patients with chronic stroke in plasma s les, which can be helpful in diagnosis, prognosis, and therapeutics of these patients.
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.ACA.2015.02.063
Abstract: This paper describes a new, efficient and versatile method for the s ling and preconcentration of PAH in environmental water matrices using special hybrid magnetic carbon nanotubes. These N-doped hiphilic CNT can be easily dispersed in any aqueous matrix due to the N containing hydrophilic part and at the same time show high efficiency for the adsorption of different PAH contaminants due to the very hydrophobic surface. After adsorption, the CNT can be easily removed from the medium by a simple magnetic separation. GC/MS analyses showed that the CNT method is more efficient than the use of polydimethylsiloxane (PDMS) with much lower solvent consumption, technical simplicity and time, showing good linearity (range 0.18-80.00 μg L(-1)) and determination coefficient (R(2) > 0.9810). The limit of detection ranged from 0.05 to 0.42 μg L(-1) with limit of quantification from 0.18 to 1.40 μg L(-1). Recovery (n=9) ranged from 80.50 ± 10 to 105.40 ± 12%. Intraday precision (RSD, n=9) ranged from 1.91 to 9.01%, whereas inter day precision (RSD, n=9) ranged from 7.02 to 17.94%. The method was applied to the analyses of PAH in four lake water s les collected in Belo Horizonte City, Brazil.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4NR04005H
Abstract: Due to the combination of hydrophobic/hydrophilic sections coupled with encapsulated catalyst particles, N-doped CNTs behave like magnetic tensioactive agents.
Publisher: Springer Science and Business Media LLC
Date: 18-01-2021
Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 09-2020
Publisher: Wiley
Date: 17-05-2012
DOI: 10.1002/ETC.1853
Abstract: Polycyclic aromatic hydrocarbons (PAHs) were analyzed from ambient air particulate matter <10 µm (PM(10) ) and the total suspended particulate (TSP) phase continuously for a period of six months (May-October 2010) at five s ling sites located in the urban area of Divinópolis (Minas Gerais), southeastern Brazil, near iron and steel mills. The carcinogenic potency of priority PAHs relative to benzo[a]pyrene was estimated for a period of six months. Benzo[a]pyrene equivalents were 7.52 ng/m(3) for the study period. The estimated risk of lifetime lung cancer was 6.5 × 10(-4) . A model based on the diagnostic ratio and principal component analysis was applied for source apportionment. Considering the entire study period, the burning of biomass and fuel oil accounted for about 70% of the PAH profile. An inventory was performed during the monitoring period, with 37 companies representing major industries located in the urban area. The observations were consistent with the distribution of sources and indicated that the iron and steel sector was the largest contributor.
Publisher: Elsevier BV
Date: 09-2013
Publisher: Elsevier BV
Date: 05-2011
DOI: 10.1016/J.CHROMA.2010.10.105
Abstract: Polycyclic aromatic hydrocarbons (PAH) from ambient air particulate matter (PM) were analyzed by a new method that utilized direct immersion (DI) and cold fiber (CF) SPME-GC/MS. Experimental design was used to optimize the conditions of extraction by DI-CF-SPME with a 100μm polydimethylsiloxane (PDMS) fiber. The optimal conditions included a 5min equilibration at 70°C time in an ultrasonic bath with an extraction time of 60min. The optimized method was validated by the analysis of a NIST standard reference material (SRM), 1649b urban dust. The results obtained were in good agreement with certified values. PAH recoveries for reference materials were between 88 and 98%, with a relative standard deviation ranging from 5 to 17%. Detection limits (LOD) varied from 0.02 to 1.16ng and the quantification limits (LOQ) varied from 0.05 to 3.86ng. The optimized and validated method was applied to the determination of PAH from real particulate matter (PM10) and total suspended particulate (TPS) s les collected on quartz fiber filters with high volume s lers.
Publisher: Elsevier BV
Date: 10-2022
DOI: 10.1016/J.ACA.2022.340405
Abstract: Phthalic acid esters (PAEs) are considered endocrine disruptors and potential carcinogens. Consequently, efficient and accurate environmental monitoring of trace levels of these organic pollutants is necessary to protect the population against their hazardous effects. Passive s ling techniques have gained notoriety for environmental monitoring and have been proven highly sensitive to temporal variations. This study developed a miniaturized passive s ling device (MPSD) based on hollow fiber liquid-phase microextraction (HF-LPME). The devices were calibrated in the laboratory using an automated calibration system. The results demonstrated the first-order uptake ranges for Diethyl phthalate (DEP), Diisobutyl phthalate (DiBP), Dibutyl phthalate (DBP), Benzyl butyl phthalate (BBP) and Bis(2-ethylhexyl phthalate) (DEHP) between 30 min and 24 h with s ling rates equivalent to 0.009 0.021 0.033 0.085 and 0.003 mL h
Publisher: Elsevier BV
Date: 07-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4AN00583J
Abstract: Metabolome analysis involves the study of small molecules that are involved in the metabolic responses that occur through patho-physiological changes caused by genetic stimuli or chemical agents.
Publisher: Informa UK Limited
Date: 20-03-2012
Publisher: Springer Science and Business Media LLC
Date: 04-2020
Publisher: Elsevier BV
Date: 07-2020
Publisher: Future Science Ltd
Date: 11-2017
Abstract: Aim: The increasing use of cocaine (COC) during breastfeeding has led to growing concern about exposure of infants. Therefore, to study this exposure, a new method to analyze COC and benzoylecgonine in breast milk was developed. Methodology: A new extraction method was used for the first time to analyze COC and its major metabolite, benzoylecgonine, in breast milk using magnetic carbon nanotubes partially doped with nitrogen. Results: The calibration curves were linear in the range 5.0–180.0 ng ml -1 . The limit of quantification was 5.0 ng ml -1 . Coefficients of variation were between 3.2 and 13.9%. Recovery was between 89.6 and 99.2%. Conclusion: The proposed method is simple, efficient and suitable to determine analytes in breast milk.
Publisher: Hindawi Limited
Date: 26-04-2023
DOI: 10.1155/2023/5561490
Abstract: The present study describes an efficient analytical method for analyzing apple pesticide residues. This novel approach employs ultrasound-assisted cleaning (UAC), solid-phase microextraction (SPME), and gas chromatography/mass spectrometry (GC-MS). A fiber coating with carbon nanomaterials (CNMs) was used for the extraction process. The methodology underwent extraction process optimization and analytical method validation. Moreover, its applicability for detecting pesticides in apples was evaluated. The validation showed satisfactory results with linearity coefficients greater than 0.99 (R2 0.99) and linear working ranges from 0.5 ng·g−1 to 300.0 ng·g−1. The limits of detection and quantification (LODs and LOQs) ranged from 0.1 ng·g−1 to 0.3 ng·g−1 and from 0.5 ng·g−1 to 0.7 ng·g−1, respectively. The calculated recovery values ranged from 79% to 98%. The precision presented a relative standard deviation (RSD) lower than 14%. The validated method was applied to apple s les acquired from different markets and fruit stands in Belo Horizonte, Minas Gerais, Brazil. Organophosphate pesticides typically used in Brazilian apple production areas were detected in some s les. This study demonstrates the utility of UAC and CNM microextraction as an effective and highly efficient approach for analyzing pesticides in apples.
Publisher: Sociedade Brasileira de Quimica (SBQ)
Date: 2023
DOI: 10.21577/0103-5053.20230005
Abstract: Metabolomics can provide a readout of the biochemical and physiological state of a biological system. Gas chromatography coupled to mass spectrometry (GC-MS) has been widely applied for metabolomic analysis due to its numerous advantages, such as good sensitivity, high resolution, reproducibility, extensive database, lower acquisition cost and greater coverage. In addition, combined with efficient methods of s ling and s le preparation, the metabolomic analysis of damaged skin based on GC-MS can provide an important step toward elucidating several skin diseases. Based on this, this review presents a comprehensive overview of s ling, s le preparation, data processing and GC-MS analysis of metabolomic studies of damaged skin. Also, part of the biological interpretation of metabolites such as cis- and trans-urocanic acid (UCA) altered in photoexposed skin and lauric acid (C12:0) and palmitic acid (C16:0) in melanoma is discussed. Finally, to improve decision-making, a part of the integration of skin metabolomics with other omics sciences for the advancement of diagnosis is presented.
Publisher: Magnolia Press
Date: 09-01-2018
DOI: 10.11646/PHYTOTAXA.333.2.2
Abstract: During a bioprospecting of fungi producing antimicrobial volatile organic compounds, two Verticillium-like isolates from coffee branches were obtained by a parallel growth technique using Muscodor albus CZ 620. Micro-morphological characteristics and phylogenetic analyses showed that both isolates belonged to Simplicillium and represented a new species, namely S. coffeanum. In the test for antimicrobial activity, the mixture of volatiles emitted by S. coffeanum COAD 2057 inhibited the growth of Aspergillus ochraceus, A. tubingensis, A. sydowii and A. niger on PDA. Among the compounds of volatile mixture, 1-Propanone, 1-(5-methyl-2-furanyl)-, Cyclopropane, 1-ethoxy-2, 2-dimethyl-3-(2-phenylethynyl)-, and 2-Propenoic acid, 3-(2-formyl-4-methoxyphenyl)-, ethyl ester, (E)- possessed the highest percentage of peak per area. Therefore, S. coffeanum has potentially biocontrol ability through the emission of antimicrobial volatiles.
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.ENVRES.2017.03.025
Abstract: This paper shows the use of exhaled air as a biomonitoring method to assess perchloroethylene (PERC) environmental and occupational exposure. A sensitive, fast, and solvent free analytical method was developed to determine PERC in ambient and exhaled air of in iduals occupationally exposed. The developed method used cold fiber solid phase microextraction (CF-SPME) as the s ling technique, and a standard permeation method to simulation of air matrix. The analysis were conducted by gas chromatography coupled to mass spectrometry (GC/MS). The methods were validated and were found to be precise, linear and sensitive for environmental and biological monitoring. The developed methods were applied to twenty-seven s ling points spread across Belo Horizonte city, Brazil, twenty four dry cleaners, an electroplating industry, a research laboratory, and an automotive paint preparation shop. The results of ambient air analyses ranging from 14.0 to 3205.0µgm
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.ACA.2018.12.017
Abstract: The extensive use of pesticides promotes environmental contamination, mainly in surface and ground waters. However, they remain at very low concentration and present wide degradation level requiring the use of efficient devices for pesticides passive s ling. In this study, a new in situ passive s ling device was developed for monitoring and estimating time-weighted average (TWA) of pesticides in waters. The device was made with simple, recyclable and cheap materials. The s ling system involves the liquid phase microextraction technique with hollow fiber in two-phases mode. Pesticides determination was done by gas chromatography coupled to mass spectrometry. The method was optimized and validated for the determination of 29 pesticides in water, showing good linearity in the range between 0.012 and 40.00 μg L
Publisher: Elsevier BV
Date: 2020
Publisher: FapUNIFESP (SciELO)
Date: 2022
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.CHROMA.2015.02.016
Abstract: Bile acids (BAs) are derived from cholesterol and produced in the liver. The most abundant bile acids in humans are usually conjugated with glycine and taurine and are ided into primary BAs such as cholic acid (CA) and chenodeoxycholic acid (CDCA) and secondary BAs like deoxycholic acid (DCA), lithocholic acid (LCA) and ursodeoxycholic acid (UDCA). The differences amongst in idual bile acids (BAs) are significant in order to distinguish different pathological processes and exposure to chemical compounds. Hollow fiber based liquid-phase microextraction (HF-LPME) is a technique that combines s le cleansing, extraction and the concentration of analytes, where a hydrophobic porous capillary membrane is impregnated with an organic extraction solvent and the lumen is filled with microliters of a phase acceptor both organic by nature. The aim of this study was to develop a new method to extract bile acids from plasma through HF-LPME of two phases (octanol as the acceptor phase) using LCMS-IT-TOF. The optimized two-phased LPME procedure for the extraction of bile acids showed limits of detection 1.0 μg L(-1) and limits of quantification of 5.0 μg L(-1). The intra-assay precision ranged from 2.1 to 11.9%. The method developed was linear over the range of 5.0-200.0 μg L(-1) for all analytes. The hollow-fiber liquid-phase microextraction method was applied to human plasma from workers exposed to organic and halogenated solvents and also to unexposed volunteers. The method is simple, low cost and it does not require large amounts of organic solvents, therefore it is quite suitable for the analysis of bile acids exposed to hepatotoxic compounds.
Publisher: Elsevier BV
Date: 2023
DOI: 10.1016/J.CHEMOSPHERE.2022.136872
Abstract: A risk assessment and a source apportionment of the particulate- and gas-phase PAHs were conducted in a high vehicular traffic and industrialized region in southeastern Brazil. Higher concentrations of PAHs were found during summer, being likely driven by the contributions of PAHs in the vapor phase caused by fire outbreaks during this period. Isomer ratio diagnostic and Principal Component Analysis (PCA) identified four potential sources in the region, in which the Positive Matrix Factorization (PMF) model confirmed and apportioned as gasoline-related (31.8%), diesel-related (25.1%), biomass burning (23.4%), and mixed sources (19.6%). The overall cancer risk had a tolerable value, with ∑CR = 4.6 × 10
Publisher: Informa UK Limited
Date: 27-03-2017
Publisher: Springer Science and Business Media LLC
Date: 20-10-2009
DOI: 10.1007/S00216-009-3206-X
Abstract: Benzene is classified as a Group I carcinogen by the International Agency for Research on Cancer (IARC). The risk assessment for benzene can be performed by monitoring environmental and occupational air, as well as biological monitoring through biomarkers. The present work developed and validated methods for benzene analysis by GC/MS using SPME as the s ling technique for ambient air and breath. The results of the analysis of air in parks and avenues demonstrated a significant difference, with average values of 4.05 and 18.26 microg m(-3), respectively, for benzene. S ling of air in the occupational environment furnished an average of 3.41 and 39.81 microg m(-3). Moreover, the correlations between ambient air and expired air showed a significant tendency to linearity (R (2) = 0.850 and R (2) = 0.879). The results obtained for two groups of employees (31.91 and 72.62 microg m(-3)) presented the same trend as that from the analysis of environmental air.
Publisher: Hindawi Limited
Date: 2016
DOI: 10.1155/2016/7058709
Abstract: This paper describes a simple and quick method for s ling and also for carrying out the preconcentration of pesticides in environmental water matrices using two-phased hollow fiber liquid phase microextraction (HF-LPME). Factors such as extraction mode, time, solvents, agitation, and salt addition were investigated in order to validate the LPME method. The following conditions were selected: 6 cm of polypropylene hollow fiber, ethyl octanoate as an acceptor phase, and extraction during 30 min under stirring at 200 rpm. The optimized method showed good linearity in the range of 0.14 to 200.00 μ g L −1 the determination coefficient ( R 2 ) was in the range of 0.9807–0.9990. The LOD ranged from 0.04 μ g L −1 to 0.44 μ g L −1 , and LOQ ranged from 0.14 μ g L −1 to 1.69 μ g L −1 . The recovery ranged from 85.17% to 114.73%. The method was applied to the analyses of pesticides in three environmental water s les (a spring and few streams) collected in a rural area from the state of Minas Gerais, Brazil.
Publisher: Springer Science and Business Media LLC
Date: 29-08-2020
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.JCHEMNEU.2013.11.002
Abstract: The analysis of amino acid levels is crucial for neuroscience studies because of the roles of these molecules as neurotransmitters and their influence on behavior. The present study describes the distribution and levels of 16 amino acids (alanine, asparagine, aspartic acid, cysteine, glycine, glutamic acid, isoleucine, leucine, lysine, methionine, phenylalanine, proline, sarcosine, serine, valine, and threonine) in brain tissues (prefrontal cortex, striatum, hippoc us and cerebellum) and the serum. Neurochemical analysis was performed on Wistar rats and C57BL/6 mice using an efficient method for extraction, a fast microwave-assisted derivatization and gas chromatography-mass spectrometry analysis. The amino acid concentration varied across brain regions for 14 of the 16 analyzed molecules, with detection limits ranging from 0.02±0.005μmolL(-1) to 7.07±0.05μmolL(-1). In rats, the concentrations of alanine, glycine, methionine, serine and threonine were higher in prefrontal cortex than in other areas, whereas in mice, the concentrations of glutamic acid, leucine and proline were highest in the hippoc us. In conclusion, this study provides a cerebral profile of amino acids in brain regions and the serum of rats and mice.
No related grants have been discovered for Helvécio Menezes.