Biparametric sequential injection system with on-line solid phase extraction for the determination of copper and zinc in waters

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Multi-syringe flow injection system for the determination of available phosphorus in soil samples

Considering the importance of monitoring the levels of nutrients present in soils and their availability to plants, an automatic methodology is proposed based on multi-syringe flow injection analysis (MSFIA) for the spectrophotometric determination of available phosphorus in soil extracts. This fully computerized flow technique allowed the development of a flow network where sample and reagents were intercalated and sent further towards the detection system. The colorimetric determination was based on the molybdenum blue method with ascorbic acid as reducing reagent and the Egner–Riehm method was applied to extract phosphorus from soil samples. A linear calibration curve was obtained between 0.75 and 15.0mgL-1. A determination frequency of 15 h-1 was achieved, with good repeatability for 12 consecutive injections of soil extracts (RSD<1.7%). The results obtained from 12 soil samples were statistically comparable to those attained by the usual batch method

Multi-syringe flow injection system with in-line microwave digestion for the determination of phosphorus

A multi-syringe system for spectrophotometric determination of total phosphorus involving in-line digestion is proposed. Sample and digestion solution were dispensed and directed towards a digestion vessel located inside a domestic microwave oven (MWO) where sample digestion took place. Afterwards, the digested sample was merged with the necessary reagents for the colorimetric determination based on the molybdenum blue method. Several digestion conditions were studied regarding composition of digestion solution, digestion time and power set on theMWO. The system was applied to waste water samples and results shown a good agreement with the reference method. Repeatable results (R.S.D. < 2.41%) and determination frequency of 12 h−1 were obtained.info:eu-repo/semantics/acceptedVersio

Use of a polymer inclusion membrane and a chelating resin for the flow-based sequential determination of copper(II) and zinc(II) in natural waters and soil leachates

A bi-parametric sequential injection method for the determination of copper(II) and zinc(II) when present together in aqueous samples was developed. This was achieved by using a non-specific colorimetric reagent (4-(2-pyridylazo)resorcinol, PAR) together with two ion-exchange polymeric materials to discriminate between the two metal ions. A polymer inclusion membrane (PIM) and a chelating resin (Chelex 100) were the chosen materials to retain zinc(II) and copper(II), respectively. The influence of the flow system parameters, such as composition of the reagent solutions, flow rates and standard/sample volume, on the method sensitivity were studied. The interference of several common metal ions was assessed, and no significant interferences were observed (<10% signal deviation). The limits of detection were 3.1 and 5.6 µg L−1 for copper(II) and zinc(II), respectively; the dynamic working range was from 10 to 40 µg L−1 for both analytes. The newly developed sequential injection analysis (SIA) system was applied to natural waters and soil leachates, and the results were in agreement with those obtained with the reference procedure.info:eu-repo/semantics/publishedVersio

Polymer inclusion membranes (PIMs) as an alternative for on-line solid phase extraction (SPE) in flow analysis

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Anti-mycobacterial activity of labdane and halimane diterpenes obtained from Plectranthus ornatus Codd

Biomedical and biopharmaceutical research : jornal de investigação biomédica e biofarmacêuticaOs produtos naturais são uma fonte única de compostos-tipofpara o desenvolvimento de fármacos em química medicinal. Vários diterpenos das espécies Plectranthus foram referidos com actividade tuberculostática interessante, sendo que o P. omatus Codd. é usado como anti-infeccioso em algumas regiões do Brasil. Em trabalhos anteriores, um diterpeno de esqueleto de halimano outro labdano foram isolados a partir de P. ornatus Codd. Neste trabalho, avaliou-se preliminarmente a sua actividade micobacteriana com uma estirpe não virulenta de Mycobacterium smegmatis. A citotoxicidade dos compostos foi testada medindo a libertação de lactato desidrogenase (LDH) não sendo encontrados efeitos citotóxicos consideráveis até 25 ug/mL. Posteriormente, o método de microdiluição foi utilizado para determinar a concentração mínima inibitória (CMI) de M. smegmatis. A CMI>99% para o esqueleto de halimano foi 100 ug/mL e >100 ug/mL para o esqueleto de labdano. De acordo com o nosso conhecimento, este é o primeiro estudo usando diterpenos de esqueleto de halimano e de labdano isolados a partir de P. omatus em ensaios de citotoxicidade em macrófagos, e num ensaio preliminar sobre a sua atividade anti-micobacteriana. Estudos futuros são sugeridos na estirpe virulenta de M. tugerculosis, particularmente para os diterpenos de esqueleto de halimano.Plectranthus spp. have been reported to have interesting tuberculostatic activity and P. ornatus Codd. has been used in some regions of Brazil as an anti-infective. Previously, diterpenes with halimane and labdane skeletons were isolated in large quantities from P. ornatus Codd. We assessed the anti-mycobacterial activity of these compounds, performing a preliminar assay with the non-virulent strain Mycobacterium smegmatis. The cytotoxicity of the diterpenes with halimane and labdane skeletons was tested with the lactate dehydrogenase assay, where no considerable cytotoxic effects were found up to 25 μg.mL-1. Subsequently, the microdilution method was used to determine the minimum inhibitory concentration (MIC) against M. smegmatis. The MIC that inhibited the growth of the non-virulent mycobacteria by ≥99% was 100 μg.mL-1 for the diterpene with halimane skeleton, whereas for the diterpene with a labdane skeleton was >100 μg.mL-1. To the best of our knowledge, this is the first report on diterpenes with halimane and labdane skeletons isolated from P. ornatus in macrophages cytotoxicity, and in a preliminar assay for anti-mycobacterial activity. Further studies are suggested on M. tuberculosis, particularly for the diterpenes with halimane skeleton

Sample introduction in multi-syringe flow injection systems: comparison between time-based and volume-based strategies

In multi-syringe flowinjection analysis (MSFIA), devices as selection, injection or commutation valves must be incorporated to the manifold to provide access to sample and standard solutions. Therefore, the definition of sample amount can be either volume or time-based. In the present work, four configurations for sample introduction (two for each approach) were tested in order to establish if the different strategies affect the analytical signal in MSFIA systems. The mean absorbance value from ten consecutive injections of a bromothymol blue solution obtained for the time-based strategy was lower than that provided by the volume-based approach as the exact volume delivered by each configuration was different from the “theoretical” volume. For time-based configurations, the exact volume delivered is 2–5% lower than the theoretical value while for volume-based configurations, the volume delivered was between 6 and 46% larger than the theoretical volume. Moreover, for time-based sampling, the order of steps in the analytical cycle was of utmost importance since any alteration in the flow direction affected the volume delivered in the subsequent step in the analytical cycle. The influence of the two sampling approaches was also evaluated in the MSFIA systems for the spectrophotometric determination of phenolic compounds and the potentiometric determination of chloride. There was no evidence that the use of either volume or time-based sampling would improve the analytical features of these determinations when real samples were tested.info:eu-repo/semantics/acceptedVersio

Seroprevalence and Risk Factors Associated with Leishmania Infection in Dogs from Portugal

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Foot and ankle disorders in nurses exposed to prolonged standing environments: a scoping review

Background: Prolonged standing environments constitute an occupational risk factor for nurses, particularly for developing foot and ankle disorders. The definitions and potential relationship to hours spent walking or standing are poorly understood. This scoping review aimed to synthesize the main disorders found on nurses’ ankles and feet, their prevalence, the influence of hours spent walking or standing, and gender differences. Methods: This review followed a previously published protocol. Primary and secondary studies were retrieved from relevant databases from December 2020 to March 2021. Potential articles were collated to Mendeley, and two independent reviewers assessed the title and abstracts. Studies meeting inclusion criteria were included. Two researchers retrieved and reviewed the full text of these studies independently. A predetermined extraction tool was used to retrieve relevant data, summarized in a tabular and narrative format. Findings: The most common disorder was pain, followed by numbness, burning feet, bunions, structural deformities, and calluses. Prevalence differed among studies, depending on settings and specific local policies. Discussion: Various foot and ankle disorders and related variables have been found, with clear gaps that may be addressed in the future. Conclusion/Applications to Practice:: Few studies have focused on nurses’ foot and ankle disorders. Mapping signs and symptoms may contribute to the future development of preventive interventions for nurses’ workplaces.info:eu-repo/semantics/publishedVersio