A review on sequential injection methods for water analysis

The development of fast, automatic and less expensive methods of analysis has always been the main aim of flowmethodologies. The search for newprocedures that still maintain the reliability and accuracy of the reference procedures is an ever growing challenge. Newrequirements are continually added to analytical methodologies, such as lower consumption of samples and reagents, miniaturisation and portability of the equipment, computer interfaces for full decision systems and so on. Therefore, the development of flow methodologies meeting the extra requirements of water analysis is a challenging work. Sequential injection analysis (SIA) presents a set of characteristics that make it highly suitable for water analysis. With sequential injection analysis, most routine determinations in waters can be performed more quickly with much lower reagent consumption when compared to reference procedures. Additionally, SIA can be a valuable tool for analyte speciation and multiparametric analysis. This paper critically reviews the overall work in this area.info:eu-repo/semantics/acceptedVersio

In-line phosphate pre-concentration in a flow injection method platform for monitoring fertilizers excess in soil leachates

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Microfluidic paper-based devices as disposable, easy-to-use, real time quantification methods

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Gas diffusion sequential injection system for the spectrophotometric determination of free chlorine with o-dianisidine

A gas diffusion sequential injection system for spectrophotometric determination of free chlorine is described. The detection is based in the colorimetric reaction between free chlorine and a low toxicity reagent o-dianisidine. A gas diffusion unit is used to isolate free chlorine from the sample in order to avoid possible interferences. This feature results from the conversion of free chlorine to molecular chlorine (gaseous) with sample acidification. With minor changes in the operating conditions, two different dynamic ranges were obtained enhancing the application both to water samples and bleaches. The results obtained with the developed system were compared to the reference method, iodometric titration and proved not to be statistically different. A detection limit of 0.6 mg ClO−/L was achieved. Repeatability was evaluated from 10 consecutive determinations being the results better than 2%. The two dynamic ranges presented different determination rates: 15 h−1 for 0.6–4.8 mg ClO−/L (water samples) and 30 h−1 for 0.047–0.188 g ClO−/L (bleaches).info:eu-repo/semantics/acceptedVersio

A flow system for the spectrophotometric determination of lead in different types of waters using ion-exchange for pre-concentration and elimination of interferences

A flow system for the spectrophotometric determination of lead in natural and waste waters is proposed. The determination is based on the colorimetric reaction between malachite green and iodide, followed by the formation of a ternary complex between those reagents and lead cations. The developed flow system includes a lead pre-concentration step in a column packed with a cationic resin (Chelex 100) operating in a sequential injection mode. To improve the mixture of sample and reagents, a flow injection approach was adopted for the colorimetric determination. This way a hybrid flow system, involving both sequential and flow injection concepts was designed. Another feature of the proposed system is the efficient elimination of major interferent species, such as cadmium and copper. The elimination of cadmium interference is obtained by complexing Cd2+ with chloride and retaining the formed negatively charged complexes in an anionic resin, AG1 X-8. As for copper, with the presence of both ionic resins as well as the conditions for cadmium elimination, it no longer acts as an interferent. Different ranges of lead concentration (50–300 and 300–1000 g l−1) can be determined with minor changes in the controlling software, useful for application to both natural and waste waters. Therefore, a detection limit of 25 g l−1 was achieved. Repeatability was evaluated from 10 consecutive determinations being the results better than 4%. The recoveries of lead spikes added to the samples ranged from 93 to 102%. The sampling frequency was 17 and 24 determinations per hour, for 50–300 and 300–1000 g l−1 ranges, respectively

Pharmaceutical vehicles for vaginal and rectal administration of anti-hiv microbicide nanosystems

Prevention strategies play a key role in the fight against HIV/AIDS. Vaginal and rectal microbicides hold great promise in tackling sexual transmission of HIV-1, but effective and safe products are yet to be approved and made available to those in need. While most efforts have been placed in finding and testing suitable active drug candidates to be used in microbicide development, the last decade also saw considerable advances in the design of adequate carrier systems and formulations that could lead to products presenting enhanced performance in protecting from infection. One strategy demonstrating great potential encompasses the use of nanosystems, either with intrinsic antiviral activity or acting as carriers for promising microbicide drug candidates. Polymeric nanoparticles, in particular, have been shown to be able to enhance mucosal distribution and retention of promising antiretroviral compounds. One important aspect in the development of nanotechnology-based microbicides relates to the design of pharmaceutical vehicles that allow not only convenient vaginal and/or rectal administration, but also preserve or even enhance the performance of nanosystems. In this manuscript, we revise relevant work concerning the selection of vaginal/rectal dosage forms and vehicle formulation development for the administration of microbicide nanosystems. We also pinpoint major gaps in the field and provide pertinent hints for future work.This work was supported by Programa Gilead GÉNESE, Gilead Portugal (refs. PGG/046/2015 and PGG/002/2016). This article is a result of the project NORTE-01-0145-FEDER-000012, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). This work was financed by FEDER-Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020-Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020, and by Portuguese funds through FCT-Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior in the framework of the project “Institute for Research and Innovation in Health Sciences” (POCI-01-0145-FEDER-007274), and also Partnership Agreement PT2020 UID/QUI/50006/2013-POCI/01/0145/FEDER/007265. J.G. gratefully acknowledges FCT for financial support (SFRH/BD/140271/2018 scholarship)

Dinâmica populacional da mosca-branca (Bemisia argentifolii) e seus inimigos naturais em meloeiro (Cucumis melo) e melancieira (Citrullus lanatus).

Ate o final da decada de 80, mais de 50 inseticidas convencionais eram conhecidos por serem eficazes na regulacao das populacoes de Bemisia spp. Destes produtos, os melhores pertenciam aos grupos dos carbamatos e organofosforados . Contudo, as dificuldades de controle da mosca-branca devem-se a localizacao dos estadios imaturos e dos adultos na parte dorsal das folhas, a facil dispersao dos adultos pelo vento e, sobretudo, ao desenvolvimento rapido de resistencia a maioria dos inseticidas. Assim, na maior parte dos casos, a eficacia do controle quimico convencional ficou rapidamente limitada.bitstream/CNPAT-2010/5376/1/Pa-067.pd