Monitoring the Degradation of Tetracycline by Ozone in Aqueous Medium Via Atmospheric Pressure Ionization Mass Spectrometry

The degradation of tetracycline (1) by ozone in aqueous solution was investigated. High performance liquid chromatography (HPLC), UV-visible spectroscopy (UV-Vis), and total organic carbon (TOC) analyses revealed that although tetracycline was quickly consumed under this oxidative condition, it did not mineralize at all. Continuous monitoring by electrospray ionization mass spectrometry in the positive ion mode, ESI(+)-MS, revealed that tetracycline (1), detected in its protonated form ([1 + H]+) of m/z 445, reacted to yield almost exclusively two unprecedented oxidation products (2 and 3) via a net insertion of one and two oxygen atoms, respectively. Compound 2, suggested to be formed via an initial 1,3-dipolar cycloaddition of ozone at the C11a-C12 double-bond of 1, and Compound 3, proposed to be produced via a subsequent ozone attack at the C2-C3 double-bond of 2, were detected in their protonated forms in the ESI(+)-MS, i.e., [2 + H]+ of m/z 461 and [3 + H]+ of m/z 477, and were further characterized by ESI(+)-MSn. LC-APCI(+)-MS (liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry in the positive ion mode) experiments corroborated the results

Degradation of the insecticides Thiamethoxam and Imidacloprid in aqueous solution as promoted by an innovative Feº/Fe3O4 composite

The performance of an innovative Feº/Fe3O4 composite to degrade the insecticides Thiamethoxam and Imidacloprid in aqueous solution was evaluated. Factorial designs were built to investigate the influence of a number of crucial variables on such degradation processes: H2O2 concentration, solution pH, and composite mass. The solution pH was the most influential variable; hence, significant degradation rates (> 90%) was accomplished exclusively in acidic solutions (pH=2). In addition, the composite was highly efficient in promoting the degradation of both insecticides either in the presence or unpredictably in the absence of H2O2. These results thus indicated that the composite possess a dual behavior, acting as either an oxidizing or a reducing agent

Chloroform formation by chlorination of aqueous algae suspensions: online monitoring via membrane introduction mass spectrometry

Membrane introduction mass spectrometry (MIMS) was used to perform on-line monitoring of the chloroform formation via the chlorination of aqueous suspensions of several green and blue-green Brazilian algae (Microcystis panniformis, Selenastrum sp., Scenedesmus sp., Monoraphidium sp. (strain 354), Monoraphidium sp. (strain 960), and Staurastrum sp.). The influence of major parameters, such as temperature, pH, initial concentration of sodium hypochloride, filtration, and reaction time, on chloroform formation was evaluated. It was verified that the chloroform formation is strongly dependent on the alga type and is favored by high temperatures, pH, sodium hypochloride initial concentration and reaction time. Finally, filtered algae samples produce smaller amounts of chloroform in comparison to the rough suspension.A técnica MIMS (membrane introduction mass spectrometry) foi utilizada para monitorar a formação de clorofórmio durante a cloração de suspensões aquosas de várias espécies brasileiras de algas verdes e azuis (Microcystis panniformis, Selenastrum sp., Scenedesmus sp., Monoraphidium sp. (strain 354), Monoraphidium sp. (strain 960), and Staurastrum sp.). Foram avaliadas as influências de parâmetros como temperatura, pH, concentração inicial de hipoclorito de sódio, filtração e tempo de reação. Foi constatado que o teor de clorofórmio é fortemente dependente da espécie de alga e também é favorecido com o aumento da temperatura, pH, dosagem de cloro inicial e do tempo de reação. Amostras de suspensões de algas submetidas a filtração produziram menores quantidades de clorofórmio em comparação com as amostras brutas.950955Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

An appraisal on the source-to-sink relationship in plants: an application of desorption electrospray ionization mass spectrometry imaging

CAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORFAPEMIG - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAISCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOAmino acids/ureides and carbohydrates are the main nutrients for the plants growth. These metabolites are continuously translocated through the plant organism via well-known transportation mechanisms. The well-established source-to-sink relationship invol2911723CAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORFAPEMIG - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAISCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL E NÍVEL SUPERIORFAPEMIG - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAISCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOsem informaçãosem informaçãosem informaçã

Efficiency of different solvents in the extraction of bioactive compounds from Plinia cauliflora and Syzygium cumini fruits as evaluated by paper spray mass spectrometry

Jabuticaba (Plinia cauliflora) and jambolan (Syzygium cumini) fruits are rich in phenolic compounds with antioxidant properties, mostly concentrated in the peel, pulp, and seeds. Among the techniques for identifying these constituents, paper spray mass spectrometry (PS-MS) stands out as a method of ambient ionization of samples for the direct analysis of raw materials. This study aimed to determine the chemical profiles of the peel, pulp, and seeds of jabuticaba and jambolan fruits, as well as to assess the efficiency of using different solvents (water and methanol) in obtaining metabolite fingerprints of different parts of the fruits. Overall, 63 compounds were tentatively identified in the aqueous and methanolic extracts of jabuticaba and jambolan, 28 being in the positive ionization mode and 35 in the negative ionization mode. Flavonoids (40%), followed by benzoic acid derivatives (13%), fatty acids (13%), carotenoids (6%), phenylpropanoids (6%), and tannins (5%) were the groups of substances found in greater numbers, producing different fingerprints according to the parts of the fruit and the different extracting solvents used. Therefore, compounds present in jabuticaba and jambolan reinforce the nutritional and bioactive potential attributed to these fruits, due to the potentially positive effects performed by these metabolites in human health and nutrition.info:eu-repo/semantics/publishedVersio

Micromesoporous Activated Carbons as Catalysts for the Efficient Oxidation of Aqueous Sulfide

KOH activation of a mesophase pitch produces very efficient carbons for the removal of sulfide in aqueous solution, increasing the sulfur oxidation rate with the degree of activation of the carbon. These carbons are characterized by their graphitic structures, with domains of sizes of around 20 nm, and a moderate concentration of surface oxygen groups (0.2–0.5 mmol·g–1) dominating the basic groups. Because the activation leads first to a strong development of the micropores and later to a development of the mesopores, the surface area values are always high, reaching values of as high as 3250 m2·g–1 in the most activated carbon, with a volume of mesopores of as high as 44% of the total pore volume. In the presence of this carbon, the sulfide oxidation rate is 100 times higher than that found for a commercial activated carbon, the results indicating that the porosity of the carbon, especially mesoporosity, plays a role more important than the structure or the chemical nature of the carbon in the kinetics of sulfide oxidation to different polysulfides.The authors thank CNPq, CAPES, INCT, PRPq-UFMG, and Prometeo II/2014/004 for financial support