This review describes compounds produced microalgae, such as biodiesel, lipids, fatty acids (FA), triacylglycerides (TAG), and pigments (phycobilins, chlorophylls, and carotenoids). We discuss the ...factors inducing the accumulation of these metabolites and their economic importance. We focused on cell wall breaking methods of microalgae used to produce biodiesel. A special approach was made to extremophile microalgae used in biodiesel production. The type of methodology used in the cultivation and the use of extremophiles microalgae can permit feasible biodiesel production.
In the search for microalgae species with potential for biodiesel production, Choricystis minor var. minor has been seen as a promising source of biomass due to its high lipid content and the ...satisfactory characteristics of its fatty acid methyl esters (FAMEs). For this reason, the objective of this study was to investigate the synergistic effect of growth conditions and organic carbon sources on cultivation of this microalga. To do so, experimental cultivations were conducted in photoautotrophic, heterotrophic and mixotrophic metabolisms using glucose, fructose, glycerol or sucrose – in growth conditions that use organic carbon. Thus, growth parameters of the cultures were evaluated and at the end of the cultivations, FAMEs yield and profile were determined by gas chromatography, the efficiency of carbon conversion into biomass was evaluated and a microbial analysis was conducted. Regarding growth conditions, the findings have confirmed that, regardless of the organic carbon source used, the heterotrophic and mixotrophic metabolisms can present advantages over the photoautotrophic one. In addition, biomass production was higher with the use of glucose than with other organic carbon sources, regardless of growth condition (heterotrophic or mixotrophic). Moreover, cultivations with the addition of CO2 have converted carbon into biomass less efficiently. On the other hand, photoautotrophic cultures presented the lowest bacterial load. In comparison to photoautotrophic and mixotrophic, heterotrophic cultures have led to lower FAMEs content and higher yields of unsaturated fatty acids. The most satisfactory FAMEs profile for biodiesel production was obtained with mixotrophic growth using fructose.
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•The synergetic effect of growth conditions and organic carbon sources was investigated.•The addition of organic carbon has promoted an increase in the Choricystis minor var. minor biovolume.•Mixotrophic cultures have improved biomass production and FAMEs yield.•Mixotrophic cultures using fructose have increased saturated fatty acids content.•The use of glycerol and sucrose in the presence of light has probably induced photoheterotrophy.
This study describes the development of a new electrochemical paper-based analytical device (ePAD) on alumina sandpaper substrate through a pencil-drawing process for square wave voltammetry ...measurements of midazolam maleate used as a “date rape drug” in beverages. The proposed ePAD was assembled on a reusable 3D printed holder to delimit its geometric area and ensure better robustness. The ePAD was characterized by scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and Raman spectroscopy. The direct drawing of ePADs on sandpaper platforms through a graphite pencil has offered suitable repeatability (RSD = 1.0%) and reproducibility (RSD = 4.0%) using Fe(CN)64– as redox probe. The proposed ePAD provided linear behaviour in the midazolam maleate concentration range between 2.5 and 150 mg L−1 and a limit of detection of 2.0 mg L−1. The feasibility of the ePAD for forensic application was successfully demonstrated through the detection of midazolam in different beverages (water, beer, liquor, and vodka). The intended application revealed low interference of other compounds present in beverages. Based on the achieved results, the proposed ePAD has offered great accuracy with no statistical difference at 95% confidence level from the data recorded by high performance liquid chromatography. The operational simplicity and the robustness ensured by the assembling on a reusable 3D printed holder make the ePAD drawn on sandpaper platform a powerful and promising analytical tool for the analysis of “date rape drugs” opening new possibilities for on-site forensic investigations.
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•Sandpaper substrate was explored to fabricate electrochemical devices through pencil drawing protocol.•ePADs were assembled on a reusable 3D-printed holder and covered with PDMS to define the geometric area.•The forensic feasibility was demonstrated through the detection of date rape drug.•The achieved results revealed good agreement with the data recorded using HPLC.•The proposed assembled device offered operational simplicity and an environmentally friendly strategy.
Steroids are called the “fingerprint”
of oils, fats,
and their derivatives. Different classes of steroids may be present
in these matrices. Most of the methods developed to analyze these
constituents ...involve the determination of free steroid content, although
their conjugated forms are extremely important in determining the
total composition. Thus, this article demonstrates that the coupling
of sequential mass spectrometry and high-performance liquid chromatography obtained
high sensitivity and high specificity of mass resolution to identify
and quantify the main classes of steroids. Four methods were developed
to quantify steroids free, esterified, glucosides, and acylated glucosides
by internal standardization using betulin. The main validation parameters
were tested and demonstrated good correlation results for the methods.
The content of free steroids was the majority in all samples, whereas
the content of glucoside steroids was the least abundant. The contents
of free steroids quantified in the degummed soybean oil were significantly
reduced in relation to the refined oil. A small amount of esterified
steroids was superior in refined soybean oil than in degummed oil.
Comparing the steroid content between degummed oil and biodiesel,
we found that the concentration of free and esterified steroids decreases
in the conversion to biodiesel, whereas the concentration of glucoside
steroids increases slightly.
Petroleomics, which is the characterization, separation, and quantification of the components of petroleum and crude oil, is an emerging area of study. However, the repertoire of analytical methods ...available to understand commercial automotive lubricant oils (ALOs) is very limited. Ambient mass spectrometry is one of the most sensitive analytical methods for real-time and in situ chemical analysis. With this technique, the chemical fingerprinting of ALOs can be performed quickly and simply using dielectric barrier discharge ionization time-of-flight mass spectrometry. In this study, the mass spectra of 35 samples were obtained without any sample preparation in positive-ion mode, and no carryover was observed. To elucidate the similarities and differences between the ALO samples, the data generated from these spectra were analyzed using four chemometric techniques: principal component analysis, multivariate curve resolution, hierarchical cluster analysis, and pattern recognition entropy. The ALO samples were readily differentiated according to their American Petroleum Institute classification and base oil types: mineral, semisynthetic, and synthetic. The development of this new methodology will aid in the semiquantitative control analysis of ALOs and offers an improved ability to identify the components therein.
•Ten biodiesel types from various raw materials were studied in composition free steroids.•Contents of steroids present in biodiesel determined by GC-FID showed great variability among them.•Results ...obtained by GC–MS were used in identification of steroids quantified.•Types of steroids present in biodiesel and its own peculiar distribution showed that some steroids were exclusive.•Composition of steroids in this study allows the identification of different types of biodiesel in a blend them.
This study aimed to extract, characterize and quantify free steroids present on various types of methyl biodiesel produced in the laboratory from different raw materials and a special type of commercial biodiesel. Steroid extraction was performed by sample saponification followed by solvent extraction of insaponificable. Steroid characterization was obtained by gas chromatograph equipped with a flame ionization detector (GC-FID) and by gas chromatograph coupled with a mass spectrometer (GC–MS); steroid quantification was performed by GC-FID. Several different free steroids found present in the biodiesel types were analyzed; some of them were identified as exclusive to certain biodiesel types. It was possible, based on the present free steroid profile analysis methodology, to identify the origin of a commercial biodiesel. Analyses had show that steroid content in biodiesel types ranged from 610mgkg−1 in the babassu biodiesel to 3250mgkg−1 in the crambe biodiesel.
The present study reports the development of a bioassay using Artemia spp. to analyse the preliminary ecotoxicity of atmospheric aerosols (PM), which can affect the environment and human health. ...Herein, PM samples were collected in the city of Goiânia (Brazil) in 2016, extracted with ultrapure water and subsequently filtered through membranes with different pore sizes (100, 0.8, and 0.22 μm), and the extracts employed in the bioassays. The mortality rates (endpoint analysed) declined to membranes with smaller pore sizes (15 ± 4%, 47 ± 10% and 43 ± 9% for pore sizes of 100 μm, 0.8 μm and 0.22 μm, respectively). In general, the toxicity of the extract depended on its concentration, except for the sample with a higher negative particle surface charge, which presents a lower affinity for the negatively charged surfaces of cellular membranes. Moreover, although the PM concentration was higher for the sample collected during the dry season (September), the mortality rate was not significantly different to that determined for a sample with similar physical and chemical characteristics collected in the rainy season (December). This result demonstrates the importance of monitoring PM toxicities and their chemical and physical characteristics, in addition to their concentrations. Therefore, the new protocol to provide a preliminary analysis of the toxicity of the extracts of aerosol emerges as a useful, accessible, and fast tool for monitoring possible environmental hazards, and can simplify fieldwork.
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•A new protocol to measure the preliminary ecotoxicity of atmospheric aerosol samples.•The ecotoxicological impact of atmospheric aerosol upon Artemia spp.•Aerosol samples collected in the dry and wet seasons exhibit ecotoxicity.•The toxicity showed dependence on particle size and concentration.
•The new method allows the determination of biodiesel content in diesel blends.•It is applied in a large range of biodiesel content in biodiesel/diesel blends.•It is applicable to colorimetric device ...operating at 420–440nm wavelength range.
In this paper a new quantitative analytical method is described for determining the biodiesel content in biodiesel/diesel mixture through of the fatty acid methyl ester reaction with hydroxylamine hydrochloride and iron(III) nitrate. The ferric hydroxamate complex diluted in n-heptane was analyzed by UV–visible spectroscopy in a range of 420–440nm wavelength to determine the biodiesel content in biodiesel/diesel blends. The method has shown excellent repeatability and linearity for determining biodiesel content in biodiesel/diesel blends in the 0.5–5.0% quantification range and in small intervals of biodiesel content in diesel oil (0.1%). For levels over 5% of biodiesel in biodiesel/diesel blends, the linearity and repeatability is also excellent but it is necessary to increase the dilution of n-heptane of the ferric hydroxamate complex to still obtain a linear relationship between concentration and absorbance. The results obtained for biodiesel produced from different feedstocks are very similar, except for biodiesel produced from castor oil, what means that the method purposed has low influence of the feedstock used in biodiesel production. The parameters evaluated indicate that the method proposed is analytically reliable for determining biodiesel content in biodiesel/diesel blends.
When the biodiesel enters the crankcase, its degradation can lead to the formation of organic acids and polymerisation, to the point of clogging the system and the internal combustion engines. ...Therefore, this article proposed the study of lubricant oils in order to trace its biodiesel contamination. The results showed that in relation to the viscosity at 40°C there was reduction above the limit allowed for some samples. The viscosity index results showed considerable changes. Using infrared spectroscopy was noted that the contamination by fatty acid esters does not follow a pattern related to time of use in the motor. However, as the lubricant oil samples were used, they probably contain degradation products that altered the levels of oxygenated compounds. For this reason, the mass spectrometry coupled to gas chromatography quantified the predominant oil and fat steroids contents and confirmed the contamination by biodiesel.
► The simultaneous GC analysis of total esters, acylglycerides and glycerol was developed. ► The method provides separation of acylglycerides, methyl and ethyl esters peaks. ► It was used C23:0 as ...internal standard. ► The method developed is faster and allows the elution of long-chain triacylglycerides.
The purpose of this paper was to develop and validate a simple adapted method for the quality control of the determination of total esters, mono-, di-, and triacylglycerides and free and total glycerol content in methyl or ethyl biodiesel. Advantages of the method over the standard EN 14103 and EN 14105 methods include reduced sample preparation and analysis time and wide applicability to biodiesel containing naturally occurring heptadecanoic acids. The method correlates well with the standard EN 14103 and the EN 14105 methods.
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