Monosegemented flow potentiometric titration for the determination of chloride in milk and wine

An automated flow potentiometric titration procedure for the determination of chloride in milk and wine exploiting the monosegmented flow approach is described. The flow network was designed based on a six-way solenoid valve, controlled by a microcomputer running software written in VisualBasic 3.0, allowing selection of the titration conditions. An Ag2S tubular electrode selective for Cl- and a conventional Ag/AgCl electrode were employed as indicator and reference, respectively. An algorithm based on the potential difference between two subsequent titrant additions was developed, allowing to reach the end point in less than 10 attempts, with a precision better than 1.0%. The proposed system was evaluated by determining chloride in milk and wine, using a standard AgNO3 solution as titrant. Accuracy was ascertained by comparing the results with those obtained using the AOAC procedure. No significant difference at a 95% confidence level was observed.Este trabalho descreve um procedimento automático em fluxo monossegmentado para titulação potenciométrica aplicado à determinação de cloreto em leite e vinho. O sistema de fluxo foi desenvolvido com base em uma válvula solenóide de 6 vias, controlada por um microcomputador através de um programa escrito em VisualBasic 3.0. Um eletrodo indicador tubular de Ag2S seletivo a Cl- e um eletrodo de referência convencional de Ag/AgCl foram empregados. Um algoritmo baseado na diferença de potencial entre duas adições subsequentes de titulante foi desenvolvido, possibilitando a determinação do ponto final da titulação em, no máximo, 10 tentativas, com uma precisão melhor que 1,0%. O sistema proposto foi avaliado pela determinação de cloreto em leite e vinho, usando uma solução padrão de AgNO3 como titulante. A exatidão foi avaliada comparando-se os resultados com aqueles obtidos pelo método da AOAC, não sendo encontradas diferenças significativas ao nível de confiança de 95%.259264Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

A versatile set up for implementing different flow analysis approaches Spectrophotometric determination of nickel in steel alloys

Abstract An arrangement capable of implementing the four principal types of flow analysis processes, monosegmented flow analysis (MSFA), flow injection analysis with multicommutation and binary sampling (FIA-MBS), flow injection analysis with sandwich sampling (FIA-SS) and sequential injection analysis (SIA) is described. The core of the flow manifold is a six-way solenoid valve that is assembled together with three three-way solenoid valves in order to provide a versatile flow network. Software was written in VisualBasic 3.0 to give a friendly working structure allowing the user to easily choose the flow variables and the kind of flow system. The reliability of the flow set up for implementation of the four flow analysis systems was evaluated by means of the spectrophotometric determination of nickel in steel alloys, based on the formation of a colored complex with dimethylglyoxime (DMG). The performances of the four different flow methodologies were compared. The reagent consumptions per determination were 4.0 mg of triethanolamine, 6.0 mg of potassium persulfate and 0.6 mg of DMG. When the flow set up was instructed through the software to implement MSFA, FIA-MBS, and FIA-SS approaches, a sampling frequency of 40 samples/h was obtained, while 30 samples could be processed per hour in the SIA mode. The precisions, evaluated as the relative standard deviation of ten determinations were 0.7%, 1.6%, 1.8% and 3.1% for the MFSA, FIA-MBS, FIA-SS and SIA systems, respectively. The results for determination of nickel in steel alloys presented good agreement with the reference method (ICP OES), showing no significant difference at a confidence level of 95%.

COMPREENSOES ACERCA DA CURRICULARIZACAO DA EXTENSAO EM CURSOS DE COMPUTACAO DO CENTRO-OESTE

A curricularização da Extensão se tornou obrigatória a partir da Resolução n.º 7 MEC/CNE/CES de 2018, que determina a inclusão de atividades de Extensão no currículo dos cursos superiores no Brasil. Este artigo apresenta um mapeamento da situação da curricularização da extensão em cursos superiores de Computação em Institutos Federais e Universidades públicas na região Centro-Oeste do Brasil. A pesquisa foi realizada a partir de documentos públicos de Projetos Pedagógicos de Cursos (PPC).  Foram realizadas análises considerando a instituição de ensino e a sua modalidade (bacharelado ou tecnológico). A análise de 67 PPC revelou que a maioria dos cursos da região ainda não se adequou à regulamentação vigente. Ao analisar os cursos que implementaram a curricularização da extensão, foram observados que inclusão de componentes curriculares dedicados à Extensão é uma prática predominante

Terpenoid biotransformations by Mucor species

Terpenoids are natural products of great interest due to their widespread use in agrochemicals, drugs, fragrances, flavouring and pigments. Biocatalysts are increasingly being used in the search for new derivatives with improved properties especially to obtain structurally novel leads for new drugs which are difficult to obtain using conventional organic chemical methods. This review, covering up to the end of 2012, reports on the application of Mucor species as catalysts in terpenoid biotransformation to obtain new drug targets, enhance pharmacological activity or decrease the unwanted effects of starting material

Melanoides tuberculata as intermediate host of Philophthalmus gralli in Brazil

Melanoides tuberculata that naturally harbored trematode larvae were collected at the Pampulha dam, Belo Horizonte (Minas Gerais, Brazil), during malacological surveys conducted from 2006 to 2010. From 7,164 specimens of M. tuberculata collected, 25 (0.35%) were infected by cercariae, which have been morphologically characterized as belonging to the Megalurous group, genus Philophthalmus. Excysted metacercariae were used for successful experimental infection of Gallus gallus domesticus, and adult parasites recovered from the nictitating membranes of chickens were identified as Philophthalmus gralli. This is the first report of P. gralli in M. tuberculata in Brazil