Samantha R.C. Silva

Determination of lipid content of oleaginous microalgal biomass by NMR spectroscopic and GC–MS techniques

AbstractDirect methods based on 1H NMR spectroscopic techniques have been developed for the determination of neutral lipids (triglycerides and free fatty acids) and polar lipids (glyceroglycolipids/phospholipids) in the solvent extracts of oleaginous microalgal biomasses cultivated on a laboratory scale with two species in different media. The chemical shift assignments observed in the 1H and 13C NMR spectra corresponding to unsaturated (C18:N, N = 1–3, C20:3, C20:5, C22:6, epoxy) and saturated (C14–C18) fatty acid ester components in a complex matrix involving overlapped resonances have been unambiguously confirmed by the application of 2D NMR spectroscopy (total correlation spectroscopy and heteronuclear single quantum coherence–total correlation spectroscopy). The study of the effect of a polar lipid matrix on the determination of neutral lipids by an internal reference blending process by a systematic designed experimental protocol has provided absolute quantification. The fatty acid composition of algal extracts was found to be similar to that of vegetable oils containing saturated (C16–C18:0) and unsaturated (C18:N, N = 1–3, C20:N, N = 3–4, C22:6) fatty acids as confirmed by NMR spectroscopy and gas chromatography–mass spectrometry analyses. The NMR methods developed offer great potential for rapid screening of algal strains for generation of algal biomass with the desired lipid content, quality, and potential for biodiesel and value-added polyunsaturated fatty acids in view of the cost economics of the overall cost of generation of the biomass. Graphical Abstract500 MHz full 1H-13C 2D HSQC-TOCSY contour plot of algae extract SNDSPSClMe. b, a= C18:3, C22:6; c, e= epoxy ester; n= C22:6; q= absence of C20:5; f, g= OCH2 (sn1, sn3) and h= OCH (sn2)

Documentoscopy by atomic force microscopy (AFM) coupled with Raman microspectroscopy: applications in banknote and driver license analyses

Document examination to determine document authenticity is an important field in forensic science. Methods of counterfeiting have become sophisticated, so the development of informative and effective tools for questioned document examination becomes necessary and challenging. Atomic force microscopy (AFM) and Raman microspectroscopy have been shown to be advantageous, allowing the comparison of inks, the sequencing of crossing lines, and providing physicochemical information about the nature of the paper and of the ink deposition mechanism. Herein, AFM and Raman techniques are explored for the analysis of both authentic and counterfeit Brazilian driver licenses, and national and international banknotes. For AFM results, parameters, such as roughness and topographic profiles of the chalcographic region of banknotes and Brazilian driver licenses, are sufficient to visually discriminate between authentic and counterfeit documents. However, statistical analysis using the Students t-test showed that the asymmetry (SSK) values obtained from series numbers and micro-letter regions identified the counterfeiting. Compared to the topographic profile obtained for homemade banknotes produced by different printers (inkjet and LaserJet), the AFM technique indicated that the paper used to counterfeit the Brazilian driver license and the real banknote was an “office” type with inkjet printing. For Raman spectroscopy results, bands of phthalocyanine, and diarylide (diazo) pigments, and carbon black were identified in authentic documents, whereas for counterfeit documents, only a high fluorescence was observed. The obtained data were reproducible via the video spectral comparison (VSC) technique, typically used by forensic police laboratories.

Use of the Comprehensive Two-Dimensional Gas Chromatography (GC×GC-qMS) to Characterize The Classes of Saturated Compounds in Brazilian crude Oils

Brazilian oil production of pre-salt layer consists of oils with high content of saturated compounds. The identification of paraffinic and naphthenic compounds in these crude oils is key to understanding their rheological behavior. In the present study, comprehensive two-dimensional gas chromatography was performed to assess the greater separation capacity of products when compared with one-dimensional gas chromatography. Accordingly, it was possible to estimate relative the various classes existing in the saturated fraction of the crude oil. The results indicate that naphthenic compounds (53-77%) are more abundant than n-paraffins and iso-paraffins (22-46%) in nonpolar petroleum fractions from medium to low gravity, according American Petroleum Institute (API). Light oils showed high amount of iso-paraffins (37%), and the second most abundant class was the monocyclic compounds (30%). Crude oils with high pour point showed higher amount of heavy n-paraffins than oils with low pour point, suggesting a correlation between pour point and high molecular weight n-paraffins.

Fungicides in red wines produced in South America

ABSTRACT Although recent research has shown that pesticides can remain in wine, there is only legislation regarding the level of pesticides in grapes; no such regulations exist for wine. Therefore, the objective of this work was to evaluate the presence of fungicides in 190 wines produced in southern South America, as well as to present a new method for the quantification of dithiocarbamates. The fungicides were analysed by LC-MS/MS and GC/MS using validated methods according to the SANTE recommendations. The results for dithiocarbamates are expressed in mancozeb equivalents and are reported herein for the first time. Of the 190 wines analysed, 40% had residues from at least one fungicide detected above the LOQ, and 16.3% of the wines contained levels of fungicides above the MRL for grapes. The fungicides most commonly found were dithiocarbamates, azoxystrobin, carbendazim, difenoconazole, dimethomorph and cyprodinil. The new method for quantification of dithiocarbamates presented high accuracy (89.8–108.1%) and precision (HorRat values between: 0.5 – 1.1). GRAPHICAL ABSTRACT

Improvement on Pour Point of Heavy Oils by Adding Organic Solvents

This paper describes pour point behavior of three heavy oils with the addition of kerosene, turpentine, toluene and gas condensate. The study showed a decrease in the pour point of all oils that relates with the oil chemical composition. The oil with lower API gravity (higher amount of asphaltenes and resins) showed higher pour point decay for all solvents, highlighting gas condensate and turpentine. The use of gas condensate to reduce the pour point of heavy oils is particularly advantageous, when available in the oilfield. Prevent the stoppage in the oil production, due to clogging and flow problems in the pipelines, and facilitate the logistics, reducing process operational costs