Marcos A. Pudenzi

Petroleomics by ion mobility mass spectrometry: resolution and characterization of contaminants and additives in crude oils and petrofuels

Ion mobility-mass spectrometry (IM-MS), performed with exceptional resolution and sensitivity in a new uniform-field drift tube ion mobility quadrupole time-of-flight (IM-QTOF) instrument, is shown to provide a useful tool for resolving and characterizing crude oils and their contaminants, as well as petrofuels and their additives. Whereas direct analysis of a crude oil sample contaminated with demulsifiers by the classical ESI(±)-FTICR-MS petroleomic approach was unsatisfactory since it responds only with abundance and m/z, and ionization is impaired due to suppression of polar compounds of crude oil by additives likely used in petroleum industry, IM-MS enables mobility separation of ions, particularly of double bond equivalent (DBE) series for a giving CnX class providing separated spectra which are typical obtained either for the crude oil or the contaminants, even suffering of ion suppression or low ionization efficiency. The combination of improved IM resolution and high mass resolving power (40,000@400) of the QTOF instrument provides useful information on class (N, NO, NS, etc.), carbon number (Cn), and unsaturation (DBE) levels for crude oils, allowing one to infer geochemical properties from DBE trends that can be compared with IM-MS data. As demonstrated by results of gasoline samples with additives, the IM-MS system also allows efficient separation and characterization of additives and contaminants in petrofuels.

Profiles of phenolic compounds by FT-ICR MS and antioxidative and antiproliferative activities of Stryphnodendron obovatum Benth leaf extracts

Stryphnodendron obovatum Benth is a Brazilian Cerrado tree, which is rich in catechin derivatives, being therefore widely used in folk medicine. Its seeds, beans and bark have been used for various medicinal purposes, but few reports have tried to correlate their biological activity with their chemical composition. In this study, we have profiled the main phenolic constituents of S. obovatum leaf extracts by ultrahigh resolution mass spectrometry (FT-ICR MS), and tried to establish a correlation of metabolites and antioxidant and in vitro antiproliferative activities. In the methanolic extract flavonoid derivatives were detected and they presented the most promising scavenging activities for methanolic extracts (EC50 0.86 ± 0.01 μg mL−1), being slightly more active than Trolox (EC50 1.13 ± 0.09 μg mL−1). In the hydroethanolic extract, catechin derivatives as well as protocatechuic acid-glucoside were detected and found to be a little less active than the control (EC50 1.39 ± 0.01 μg mL−1). The best performance in terms of antiproliferative activity was found for the methanolic extract for renal cell lines (TGI 40.6 g mL−1).

Study of Naphthenic Acidity and Corrosivity of Brazilian Crude Oils by ESI(-) FT-ICR MS

Nos ultimos anos grande parte das reservas de petroleo descobertas no Brasil, com excecao das grandes reservas do pre-sal, bem como em todo o mundo, compreendem oleos de baixo grau API e de alto numero de acidez total (Total Acid Number, TAN). Os acidos naftenicos sao os principais compostos responsaveis por esta elevada acidez, o que leva a muitos problemas na industria petrolifera, tais como a corrosao durante o processo de producao. Neste contexto, o objetivo deste trabalho foi avaliar a acidez naftenica e o potencial corrosivo de 35 amostras de oleos brasileiros utilizando a abundância relativa da classe O2 obtida por espectrometria de massas de ressonância ciclotronica de ions com transformada de Fourier (FT-ICR MS) acoplada a uma fonte de ionizacao por electrospray (ESI) no modo negativo, correlacionando-a com o numero de acidez total (TAN) e a taxa de corrosao em um tipo de aco inoxidavel comumente utilizado em torres de destilacao de refinarias de petroleo. Foi observada uma baixa relacao entre a abundância da classe O2 e o TAN, provavelmente devido a compostos de outras classes heteroatomicas que podem ter contribuido para a acidez total. Alem disso, neste estudo a %O2 se mostrou mais coerente para avaliar a corrosividade dos petroleos avaliados do que o TAN, baseando-se nos testes de corrosao com cupons do aco 316L.

Petroleomics via Orbitrap mass spectrometry with resolving power above 1 000 000 at m/z 200

The performance of the high-field MegaOrbitrap Fourier transform mass spectrometer (FT-MS) with electrospray ionization (ESI) was evaluated to perform petroleum sample characterization via classical petroleomics approaches. Pertinent parameters that underpin the main figures of merit, that is, signal to noise ratios, dynamic range, spectral error, scan speed, mass accuracy and mass resolving power = Rp, and provide subsidies to develop these analyzers were tested. Comparisons are made with data obtained using the most common petroleomics instrument, which is a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS), that has been used in the last decade in our laboratory for crude oil analysis providing Rp of 340 000 at m/z 400 with transients of 3 s duration, and has been extensively demonstrated to fulfill all major requirements for precise petroleomics investigations. The high-field compact MegaOrbitrap mass analyzer, when operated at an Rp = 840 000 at m/z 400 (Rp > 1 000 000 at m/z 200) with a detection time of 3 s, was found to be well suited for adequate characterization of crude oil. Accurate class classification and mass accuracy below 1 ppm was obtained leading to proper, comprehensive petroleomics characterization.