Microwave-Assisted Extraction of Fatty Acids from Cultured and Commercial Phytoplankton Species

(1) Background: The extraction of fatty acids from microalgae and cyanobacteria is mostly performed with organic solvents and laborious procedures. Microwave-assisted extraction (MAE) can be a more effective and environmentally friendly process than traditional extraction (TE), which uses a large volume of solvent and conduction heating. Freshwater phytoplankton inhabits diverse aquatic environments and is a promising source of fatty acids and green precursors in the synthesis of biofuel, including cyanobacterial biomass. Therefore, the aim of this study was to investigate the potential of MAE to extract fatty acids from a Chlorella sp. microalga and two cyanobacteria, namely, Arthrospira sp. and Sphaerospermopsis torques-reginae, for biodiesel production. For this purpose, the lipid content and fatty acid profile of these strains were compared after treating biomass with the two extraction methods. (2) Methods: MAE and TE were used as extraction procedures; gas chromatography\u2013mass spectrometry was used to assess the fatty acid profiles, and X-ray spectroscopy was used to analyze biomass. (3) Results: Although the fatty acid profile of the oil obtained by TE showed higher concentrations of fatty acids, the MAE method was able to extract more types of fatty acids. The variety of fatty acids extracted by the MAE, especially those with unsaturated chains, allowed for better quality biodiesel, presenting advantages over previous methods and studies. According to the analyses, essential fatty acids 16:0, 16:1, and 18:2 were found to be abundant in both cyanobacterial strains and in microalga, showing potential for biofuel production. Additionally, metal composition was determined as its content may indicate potential pro-oxidant influence in biofuel production. (4) Conclusions: MAE is a useful and green strategy to extract fatty acids from freshwater phytoplankton. Cyanobacteria can also be a beneficial source of fatty acids for biodiesel synthesis

Obtenção de biodiesel por transesterificação em dois estágios e sua caracterização por cromatografia gasosa: óleos e gorduras em laboratório de química orgânica

Methanolic transesterification of oils and fats was carried out in a two steps procedure, under basic and acidic catalysis. Palm, soybean, canola, corn, rice, grapeseed, sunflower, peanut, pequi and olive oils, besides tallow and lard were used as feedstock. Specific gravity, relative viscosity, thin layer chromatography and gas chromatography were used to characterize the biodiesel. Biodiesel was obtained in high yield and purity. Results were used to discuss the following key-concepts: 1 - triglycerides, composition and properties; 2 - nucleophilic acyl substitution under basic and acid conditions, 3 - thin layer chromatography, 4 - gas chromatography and its quantitative methods

Development of Analytical Method for the Determination of Cd and Pb in Samples of Xanthan Gum by GF AAS.

This work presents the development of a method for the determination of Cd and Pb in xanthan gum samples by graphite furnace atomic absorption spectrometry, using NH4H2PO4 as a chemical modifier. The preparation of the samples was made from acid decomposition using a reflux system adapted to the digesting tubes. With this system it was possible to raise the temperature of the digester block to 220 ºC, without loss of acid and/or analyts by volatilization. The samples were mineralized in 5mL of HNO3 for a period of 3 h. The detection limits for Cd and Pb were 2.2 and 33.8 ng g-1, respectively. The RSDs for both analytes were, on average, less than 5.0%. To evaluate the accuracy of the proposed method, analyse addition and recovery tests were performed, obtaining results in the range of 84 to 103% of recovery. The methodology developed was used for the analysis of three commercial samples of xanthan gum, which presented Pb concentrations below the detection limit of the method. For Cd, only one sample presented a concentration value above the quantification limit. However, the Cd content in this sample was below the limit established by the current legislation for xanthan as a food additive.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESNeste trabalho apresenta-se o desenvolvimento de um método para a determinação de Cd e Pb em amostras de goma xantana por espectrometria de absorção atômica em forno de grafite, utilizando NH4H2PO4 como modificador químico. O preparo das amostras foi feito a partir da decomposição ácidautilizando um sistema de refluxo adaptado aos tubos digestores. Com esse sistema foi possível elevar a temperatura do bloco digestor a 220 ºC, sem haver perda de ácido e/ou analitos por volatilização. As amostras foram mineralizadas em meio de 5mL de HNO3 por um período de 3 h. Os limites de detecção para Cd e Pb foram de 2,2 e 33,8 ng g-1, respectivamente. Os RSDs para ambos analitos foram, em média, menores que 5,0%. Para avaliação da exatidão do método proposto, testes de adição e recuperação de analito foram realizados, obtendo-se resultados na faixa de 84 a 103 % de recuperação. A metodologia desenvolvida foi empregada para a análise de três amostras comerciais de goma xantana, as quais apresentaram concentrações de Pb abaixo do limite de detecção do método. Já para Cd, apenas uma amostra apresentou um valor de concentração acima do limite de quantificação. No entanto, o teor de Cd nesta amostra, ficou abaixo do limite estabelecido pela legislação vigente para xantana como aditivo alimentar

Evaluation of the Toxicity of Microcyclamide Produced by Microcystis aeruginosa in Danio rerio Embryos

The genus of cyanobacteria Microcystis is one of the most recurrent in blooms and is associated with the hepatotoxin microcystin production. In addition to cyanotoxins, these bacteria produce a wide range of secondary metabolites with a wide repertoire of activities. The co-occurrence of cyanotoxins and other cyanopeptides during blooming is quite common, and the negative effects are not always limited to one class of toxins, which makes it essential to investigate the toxicity of the other compounds individually. The objective of this study was to isolate the cyanopeptide microcyclamide produced by the strain Microcystis aeruginosa LTPNA 08 by liquid chromatography coupled to high-resolution mass spectrometry with a quadrupole-time-of-flight analyzer (LC-HR-QTOF-MS/MS) and to evaluate its acute toxicity in embryos of Danio rerio through the Fish Embryo Acute Toxicity (FET) assay. The fraction containing microcyclamide (95% purity) caused lethality in 62% of the embryos after 96 h exposure (50 µg mL−1), with evidence of cardiotoxicity (cardiac edema). The calculated LC50 value was 42.98 µg mL−1 (with a concentration range of 37.79–48.89 µg mL−1). The characterization of the secondary metabolites produced by cyanobacteria and the investigation of the toxicity of these compounds individually are essential for the identification of the substances responsible for negative effects on living organisms and on the ecosystem, in addition to assisting in the development of risk management policies

Determination of total concentration and bioaccessible fraction of metals in infant cereals by MIP OES

The present study provides information about the total concentration and bioaccessible fraction of metals Al, Ba, Bi, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Pb, Ti and Zn in nine different infant cereal samples. An in vitro digestion method was employed to evaluate the bioaccessibility. The determinations were performed by microwave induced plasma optical emission spectrometry (MIP OES). The bioaccessibility varied according to the type of infant cereal sample. The values of bioaccessible fraction (minimum and maximum) for Cu, Fe, Mn, Pb and Zn were 24-68, 1-10, 7-58, 24-100 and 1-7% of the total concentration, respectively. Al and Ti presented bioaccessibility in only two samples: 6% in the multicereal A and 14% in the rice and oat cereal B, respectively. The concentration of Ba, Bi, Cd, and Cr was below the limit of detection for the bioaccessibility method. The obtained concentrations were lower than the daily recommended intake for essential and toxic elements, with exception of Pb in the rice and oat A sample776065CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP447552/2014-7; 310917/2013-1; 573894/2008-6552197/2011-42008/57808-1Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)National Council for Scientific and Technological Development (CNPq) [447552/2014-7, 310917/2013-1]; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)CAPES [552197/2011-4]; CAPESCAPES; CNPqNational Council for Scientific and Technological Development (CNPq); National Institute of Advanced Analytical Science and Technology (INCTAA) (CNPq) [573894/2008-6]; National Institute of Advanced Analytical Science and Technology (INCTAA) (FAPESP) [2008/57808-1

Determination of total concentration and bioaccessible fraction of metals in tomatoes and their derivatives by MIP OES

This study presents information about the total concentration and bioaccessible fraction of barium (Ba), calcium (Ca), cadmium (Cd), copper (Cu), iron (Fe), mercury (Hg), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), molybdenum (Mo), lead (Pb) and zinc (Zn) in different cultivars of tomato (Gaucho, Paulista, Italiano and Cherry) and their derivatives (sauce and tomato extract). The determinations were performed by microwave induced plasma optical emission spectrometry (MIP OES). The bioaccessible fraction of the elements was evaluated through in vitro digestion process and the concentrations varied between 25 and 100 % ​for Cu, Fe, Mn and Zn, depending on the type of tomato sample and its derivatives. The total concentrations for all the elements studied were below the recommendation of dietary guidelines. For Ba, only the Italiano sample presented 22 % of bioaccessibility. For Pb, the highest percentage of bioaccessible fraction was found in sauces and tomato extracts. The elements Cd, Hg, Li and Mo presented concentrations lower than the limit of detection for the bioaccessibility method96CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP573894/2008-6não tem2008/57808-

Transesterification double step process for biodiesel preparation and its chromatographic characterization : oils and fats in practical organic chemistry

Methanolic transesterification of oils and fats was carried out in a two steps procedure, under basic and acidic catalysis. Palm, soybean, canola, corn, rice, grapeseed, sunflower, peanut, pequi and olive oils, besides tallow and lard were used as feedstock. Specific gravity, relative viscosity, thin layer chromatography and gas chromatography were used to characterize the biodiesel. Biodiesel was obtained in high yield and purity. Results were used to discuss the following key-concepts: 1 – triglycerides, composition and properties; 2 – nucleophilic acyl substitution under basic and acid conditions, 3 – thin layer chromatography, 4 – gas chromatography and its quantitative methods

Macroalgae and Microalgae Biomass as Feedstock for Products Applied to Bioenergy and Food Industry: A Brief Review

This article is a brief and critical review of the state of the art in algae production in the food and energy industries. Review and experimental articles from the last five years were selected to recapitulate the reasons for interest in algae cultivation, for which we highlight the most valuable phytochemicals passing through their niches in the food market, their bioenergetic potential and the possible uses of algal waste biomass. In addition, we punctuate the advent of algae biorefineries. The objectives of this study were to list the main points related to interest in cultivation, drawing a parallel between the establishment of algae in the food market and its potential to establish itself in the energy market. It was concluded that the use of algae biorefineries has been used as a solution for the food, chemical and energy markets, despite the need for the development of broader research on industrial scale