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Principais publicações

Artigos Científicos e Projetos

2022 - 2023

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Article: Optimization of QuEChERS extraction for detection and quantification of 20 antidepressants in postmortem blood samples by LC-MS/MS

In this study, a comprehensively optimization of QuEChERS (quick, easy, cheap, effective, rugged and safe) method using design of experiments (DOE) was conducted to evaluate the best conditions to obtain the most effective extraction. Liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) analysis was performed to identify and quantify the antidepressants, with electrospray ionization acquired in positive mode. The method was validated for all analytes; the calibration curves were linear from 10–1000 ng/mL, with R2>0.98, and with LOD and LOQ defined as 10 ng/mL. Method imprecision and bias were less than 14.3% and 18.9%, respectively. Neither carryover nor interferences were observed. Overall, the optimized method was applied in postmortem real sample analysis to quantify the antidepressants. This study showed a viable method that can be applied for routine forensic analysis, with a quick and easy sample preparation and a rapid total run time of 8 min for each analysis.

Article: Molecular behavior assessment on initial stages of oil spill in terrestrial environments

The contamination of terrestrial environments by oil spills creates biological risks to humans and affects the ecosystem’s health. The studies that aim to evaluate the toxicity and changes in the environments are a field of potential interest to the scientific community. The objective of this study was to evaluate the changes in the chemical composition of crude oil fractions after the simulation of a spill in soil and sand, with emphasis on an immediate temporal investigation. Samples of intermediate (°API = 27.0) and heavy (°API = 20.9) oils from Sergipe-Alagoas basin were used. The evaporation process in the soil was highlighted; while the GC-FID chromatographic profiles demonstrated (1) the disappearance from n-C12 until n-C14 compounds, besides a decrease of more than 50% in n-C15 and n-C16 n-alkanes and (2) no changes in n-C17/Pr and n-C18/Ph ratios for both oils. Analysis of resins fraction performed by Orbitrap-MS has shown changes in the mass spectra profile and compound distribution during the soil and sand exposure process, with N1, O1, and O2 species showing changes in the relative abundance in ESI(+) mode, and O2, N1, and O1 for ESI(−). Changes in polar compounds of oil will depend on the extent of the time of interaction with soil and sand, taking into account intrinsic aspects, such as the nature of the soil and components in it as the organic matter.

Article: Rapid and direct detection of artificially aged papers employing easy ambient sonic-spray ionization mass spectrometry

Abstract
Rationale: The effort to make fake documents look real leads to the use of crickets and beverages to produce artificially aged papers, as land titles, based on yellowing caused by the use of these methods. An old practice in Brazil, called "cricketing", has led to the misappropriation of Brazilian land using these documents. We propose a rapid, simple, instantaneous and non-destructive method to identify artificially aged papers by easy ambient sonic-spray ionization mass spectrometry (EASI-MS) analysis.
Methods: Three typical aging procedures were used to obtain artificially aged papers using coffee, cola drink, and crickets, with the papers being analyzed by EASI-MS. Multivariate statistical analyses were performed on the data to find the sample groups and to study the most relevant ions of each ageing procedure. High-resolution MS (HRMS) was used to obtain the exact masses and attribute formulae to relevant ions present in the samples.
Results: The combination of EASI-MS and multivariate statistical analyses allowed us to identify the most relevant ions to classify the adulteration of documents and HRMS identified most of these relevant ions. TMS fingerprinting in combination with multivariate analysis also demonstrated that this approach can qualitatively differentiate all the examined paper samples.
Conclusions: We developed a cheap, fast and easy method that can help to elucidate counterfeit documents that have been artificially aged, helping to identify chemical additives and one that can be used in forensic laboratories.

Article: Modified SARA Method to Unravel the Complexity of Resin Fraction(s) in Crude Oil

The complexity of crude oil samples has hindered its detailed analysis and understanding. Although modern analytical methods such as ultrahigh-resolution mass spectrometry have opened the understanding of the molecular composition, discrimination due to the complexity is sabotaging a better understanding. Therefore, the SARA fractionation has been used to reduce complexity by adding a fractionation step prior to analysis. However, our studies indicate that the conventional combinations of solvents used for SARA fractionation are inefficient for the elution of heavier fractions of crude oil from the alumina stationary phase. Adding an additional step to the conventional SARA scheme provides a second resin fraction using ethyl acetate as an additional mobile phase and provides a new material that has not yet been reported. For a better understanding of the differences between both resin fractions, detailed studies have been carried out utilizing ultrahigh-resolution mass spectrometry with different types of ionization methods, one of the best scenarios to reduce discrimination and suppression effects.

Article: Forensic determination of crossing lines involving stamp and pen inks by mass spectrometry imaging

One of the most challenging tasks in forensic cases is to identify the intersection sequence of lines and inks in questionable documents, mainly in those involving significant financial values such as insurance claims, wills and contracts. Optical examination using microscopy images has been commonly used, but this morphological examination presents severe limitations that can lead to false conclusions. Herein, we show that mass spectrometry imaging (MSI) using easy ambient sonic-spray ionization (EASI) can be used to accurately identify the sequence of lines at intersecting points between stamp and pen inks. First, we used proof of concept cases and ion images, and extracted ion chronograms and EASI-MS profiles to evaluate how they could identify the intersection sequences. EASI-MSI was then used to distinguish the sequence of intersecting lines in two cases of simulated contract documents in which a signature made from pen ink was placed under or above the stamp ink. We demonstrate that EASI-MSI provided a clear indication of the actual sequence, showing that it functions as an efficient and rather unequivocal analytical tool in the examination of crossing ink lines when stamping is involved.

Article: A Rapid and Versatile Method to Determine Methanol in Biofuels
and Gasoline by Ambient Mass Spectrometry using a V‑EASI Source

Methanol is an organic compound commonly used as a solvent in the synthesis of fuel for internal combustion engines. However, the adulteration of fuels (biofuels and gasoline) with methanol is commonly practiced throughout world, and regulations to control the content of methanol in these fuels have been imposed. Although methanol in fuels can be analyzed by numerous analytical techniques, the traditional methods have some disadvantages, such as interferences, incomplete reactions, and lengthy analysis. Thus, the present work proposes a rapid and versatile methanol determination method using a simple derivatization of the sample with nicotinoyl chloride and subsequent fast analysis by ambient mass spectrometry using venturi easy ambient sonic-spray ionization (V-EASI-MS), without preseparation, taking into account all parameters of linearity, limits of detection, quantification, accuracy, and precision based on ISO 5725. We were able to develop a powerful method to quantify methanol in fuels which can be used as an alternative method to detect adulteration by government agencies.

Projeto de Pesquisa: Avaliação da contaminação ambiental da costa litorânea de Pernambuco baseada na identificação e quantificação de hidrocarbonetos alifáticos e policíclicos aromáticos do petróleo

Nas últimas semanas, toda a comunidade brasileira tem acompanhado os desdobramentos causados pelo imensurável impacto ambiental causado pela contaminação da costa litorânea do nordeste por um material proveniente de exploração petrolífera. Os impactos ambientais causados por petróleo e seus derivados é considerado um dos principais problemas globais no mundo. O petróleo é uma grande mistura de compostos químicos, dentre eles, os hidrocarbonetos são aqueles que possuem a maior parcela significativa. Mais especificamente, para ambientes aquáticos e terrestres impactados por petróleo e seus derivados, alguns hidrocarbonetos, merecem uma atenção especial. Os principais são os da classe dos hidrocarbonetos alifáticos (HAs) e os hidrocarbonetos policíclicos aromáticos (HPAs), que têm sido amplamente utilizados para caracterizar amostras de água e sedimentos, distinguindo fontes de contaminantes e avaliando o grau de contaminação ambiental, principalmente devido à sua ampla distribuição e alta toxicidade. Os estudos visando à identificação e quantificação de HAs e HPAs em sedimentos e águas empregam diferentes técnicas analíticas, propondo uma abordagem integrativa, pois se tratam de amostras com elevada complexidade química, o que torna a caracterização molecular uma tarefa complexa. Deste modo, a identificação e quantificação têm propiciado grandes desafios para os pesquisadores da área, devido à necessidade de determinação confiáveis a partir da aplicação de técnicas de alta seletividade e sensibilidade, empregando principalmente técnicas de espectrometria de massas e cromatográficas, tais como a cromatografia gasosa acoplada à espectrometria de massa - GC/MS (do inglês, gas chromatography mass spectrometry). Assim, essa proposta tem como objetivo avaliar o impacto ambiental da costa litorânea de Pernambuco, baseada na análise de sedimentos e águas, a fim de avaliar o grau de contaminação por HAs e HPAs provenientes dos recentes impactos gerados pelo derrame de petróleo em todo litoral do estado. O estudo de avaliação da contaminação será realizado envolvendo atividades de coleta, tratamento e preparo de amostras, desenvolvimento e validação de métodos analíticos instrumentais por GC/MS, aquisição e interpretação de dados. Além disso, também será realizada o monitoramento de amostras de águas e sedimentos das praias através de bioensaios ecotoxicológicos. Com vistas a dar suporte técnico-científico a essa proposta, a equipe técnica foi constituída tomando como base as habilidades e experiências em áreas do conhecimento do interesse direto aos objetivos propostos, contando com pesquisadores líderes em grupos de pesquisa que atuam em vários eixos da química analítica, ambiental e do petróleo, e ecotoxicologia. Assim, espera-se que o desenvolvimento do projeto aponte os sistemas aquáticos, mais especificamente as praias do nosso estado, que estão contaminadas e qual o nível de contaminação por compostos do petróleo e derivados de forma temporal.

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Article: Comparing Crude Oils with Different API Gravities on a Molecular Level Using Mass Spectrometric Analysis. Part 1: Whole Crude Oil

Different ionization techniques based on different principles have been applied for the direct mass spectrometric (MS) analysis of crude oils providing composition profiles. Such profiles have been used to infer a number of crude oil properties. We have tested the ability of two
major atmospheric pressure ionization techniques, electrospray ionization (ESI) and atmospheric pressure photoionization (APPI(+)), in conjunction with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The ultrahigh resolution and accuracy measurements of FT-ICR MS allow for the correlation of mass spectrometric (MS) data with crude oil American Petroleum Institute (API) gravities, which is a major quality parameter used to guide crude oil refining, and represents a value of the density of a crude oil. The double bond equivalent (DBE) distribution as a function of the classes of constituents, as well as the carbon numbers as measured by the carbon number distributions, were examined to correlate the API gravities of heavy, medium, and light crude oils with molecular FT-ICR MS data. An aromaticity tendency was found to directly correlate the FT-ICR MS data with API gravities, regardless of the ionization technique used. This means that an analysis on the molecular level can explain the differences between a heavy and a light crude oil on the basis of the aromaticity of the compounds in different classes. This tendency of FT-ICR MS with all three techniques, namely, ESI(+), ESI(􀀀), and APPI(+), indicates that the molecular composition of the constituents of crude oils is directly associated with API gravity.

Article: Comparing Crude Oils with Different API Gravities on a Molecular Level Using Mass Spectrometric Analysis. Part 2: Resins and Asphaltenes

The combination of fractionation methods for crude oils, such as saturate, aromatic, resin and asphaltene (SARA) fractionation, in combination with analysis by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been used for reducing the complexity and improving the characterization of crude oils. We have used the FT-ICR MS techniques in conjunction with electrospray ionization (ESI()) and atmospheric pressure photoionization (APPI(+)) to find trends between MS data of SARA fractions of crude oils with different American Petroleum Institute (API) gravities from the Sergipe-Alagoas basin (Brazil), focusing on the resin and asphaltene fractions.
For the first time, an adaptation of the SARA fractionation has been performed to obtain a second resin fraction, which presented compounds with an intermediate aromaticity level between the first resins and asphaltene fraction. Both the first and second resin and the asphaltene fractions were studied on a molecular level using multiple ionization techniques and FT-ICR MS to find a direct relationship between the API gravities of a heavy, medium and light crude oil. For the FT-ICR MS data and the API gravities an aromaticity tendency was found. The data show that the use of SARA fractionation with FT-ICR MS offers a tool for comprehensive characterization of individual fractions and selective chemical characterization of the components in crude oils.

Article: Advanced Aspects of Crude Oils Correlating Data of Classical
Biomarkers and Mass Spectrometry Petroleomics

The complex geochemical characteristics of crude oils can provide important information on oil generation, such as the input of organic matter and their depositional environments, also supporting exploration, extraction, and production. This work reports the first organic geochemical evaluation of oils from the first commercial Brazilian onshore field (Carmópolis, Sergipe, Brazil) via both classical biomarkers and petroleomics data collected via ultrahigh-resolution and accuracy Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Gas chromatography/mass spectrometry (GC/MS) was used to characterize the oil composition in terms of n-alkane, isoprenoid, terpane, and sterane biomarkers, whereas either positive or negative electrospray ionization (ESI) and FT-ICR were used to profile the polar constituents of the oils. GC/MS revealed geochemical characteristics that classify the oil at different levels of thermal evolution and biodegradation. FT-ICR MS attributed molecular formulas to more than 3000 polar oil constituents, allowing geochemical parameters to be inferred mainly from the carbon number (Cn) and double bond equivalent (DBE) trends, along with the N and O2 classes. The Dia27(S + R)/αααC27(S + R), % C28, and % C29 parameters and S/(S + R)αααC29, αββ(S + R)/αββ + ααα(S + R)C29, and % C27 biomarkers obtained from GC/MS were responsible to indicate similarity between samples, whereas N and O2 classes provided the most distinction among the crude oil blends in terms of the level of biodegradation and thermal maturity.

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