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Abstract: This study presents the results of an analysis of crude oil and asphaltene samples using the MALDI TOF technique. Thirty crude petroleum samples (24.53–32.05 API gravity) obtained from a Brazilian refinery were used in this study. Asphaltenes were precipitated from the corresponding crude oil samples with n-heptane. Mass spectra were acquired with a MALDI TOF mass spectrometer in a mass range of 100–1000Da. The main purpose of this study was to analyze the composition of the asphaltene molecules extracted from oil samples according to their molecular composition (molecular weight and composition heteroatoms). The mean composition of the group analyzed was calculated as follows: 17% sulfur-containing molecules, 28% nitrogen-containing molecules, 19% oxygen-containing molecules, 12% sulfur–oxygen-containing molecules and 17% nitrogen–oxygen containing molecules; only 7% of the compounds contained only hydrogen and carbon in their composition. Finally, MALDI TOF analysis can be a very efficient process with a great potential for estimating the physicochemical properties of asphaltenes. A VBA (Visual Basic for Applications) algorithm allowed us to determine the elemental composition of components of asphaltene samples. The elemental composition showed that, despite having the same physical characteristics, the chemical composition of the samples was different. [Copyright &y& Elsevier]

Abstract: Two novel peptides were isolated from the crude venom of the social wasp Polybia paulista, by using RP-HPLC under a gradient of MeCN from 5 to 60% (v/v) and named Polybine-I and -II. Further purification of these peptides under normal phase chromatography, rendered pure enough preparations to be sequenced by Edman degradation chemistry. However, both peptides did not interact with phenylisothiocyanate reagent, suggesting the existence of a chemically blocked N-terminus. Therefore, the sequences of both peptides were assigned by ESI-MS/MS under CID conditions, as follows: Polybine-I Ac-SADLVKKIWDNPAL-NH2 (Mr 1610Da) and Polybine-II Ac-SVDMVMKGLKIWPL-NH2 (Mr 1657Da). During the tandem mass spectrometry experiments, a loss of 43 a.m.u. was observed from the N-terminal residue of each peptide, suggesting the acetylation of the N-terminus. Subsequently, the peptides with and without acetylation were synthesized on solid phase and submitted to functional characterizations; the biological activities investigated were: hemolysis, chemotaxis of polymorphonucleated leukocytes (PMNL), mast cell degranulation and antibiosis. The results revealed that the acetylated peptides exhibited more pronounced chemotaxis of PMNL cells and mast cell degranulation than the respective non-acetylated congeners; no hemolytic and antibiotic activities were observed, irrespective to the blockage or not of the α-amino groups of the N-terminal residues of each peptide. Therefore, the N-terminal acetylation may be related to the increase of the inflammatory activity of both peptides. [Copyright &y& Elsevier]

Four antimicrobial peptides were purified from Royal Jelly of honeybees, by using reverse phase-HPLC and sequenced by using Q-Tof-MS/MS: PFKLSLHL-NH2 (Jelleine-I), TPFKLSLHL-NH2 (Jelleine-II), EPFKLSLHL-NH2 (Jelleine-III), and TPFKLSLH-NH2 (Jelleine-IV). The peptides were synthesized on-solid phase, purified and submitted to different biological assays: antimicrobial activity, mast cell degranulating activity and hemolysis. The Jelleines-I–III presented exclusively antimicrobial activities against yeast, Gram+ and Gram- bacteria; meanwhile, Jelleine-IV was not active in none of the assays performed. These peptides do not present any similarity with the other antimicrobial peptides from the honeybees; they are produced constitutively by the workers and secreted into Royal Jelly. [Copyright &y& Elsevier]

Describes the headspace membrane introduction mass spectrometry (HS-MIMS) technique for direct trace level analysis of volatile organic compounds in soil and other dry or wet solid mixtures. HS-MIMS signal profile; Operating parameters; Linearity, reproducibility and detection limits; Full mass spectrum acquisition.

Oral squamous cell carcinoma (OSCC) represents 90% of oral malignant neoplasms. The search for specific biomarkers for OSCC is a very active field of research contributing to establishing early diagnostic methods and unraveling underlying pathogenic mechanisms. In this work we investigated the salivary metabolites and the metabolic pathways of OSCC aiming find possible biomarkers. Salivary metabolites samples from 27 OSCC patients and 41 control individuals were compared through a gas chromatography coupled to a mass spectrometer (GC-MS) technique. Our results allowed identification of pathways of the malate-aspartate shuttle, the beta-alanine metabolism, and the Warburg effect. The possible salivary biomarkers were identified using the area under receiver-operating curve (AUC) criterion. Twenty-four metabolites were identified with AUC > 0.8. Using the threshold of AUC = 0.9 we find malic acid, maltose, protocatechuic acid, lactose, 2-ketoadipic, and catechol metabolites expressed. We notice that this is the first report of salivary metabolome in South American oral cancer patients, to the best of our knowledge. Our findings regarding these metabolic changes are important in discovering salivary biomarkers of OSCC patients. However, additional work needs to be performed considering larger populations to validate our results. [ABSTRACT FROM AUTHOR]

Discusses the detection of volatile organic compounds (VOCs) in aqueous solution at low parts-per-trillion levels using an on-line preconcentration cryotrap membrane introduction mass spectrometry (CT-MIMS) system. Comparison of the CT-MIMS with conventional MIMS; Detection of VOCs at very low concentrations through the sensitivity of the CT-MIMS system.