Enantioselectivity in the Ecotoxicity of Amphetamine Using Daphnia magna as the Aquatic Model Organism: Morphophysiological, Behavioral, Reproductive and Biochemical Parameters.

Amphetamine (AMP) is a chiral psychoactive substance that exhibits enantioselectivity in its pharmacological properties. It has been detected in wastewaters and surface waters and can occur as enantiomeric mixtures, but little is known about its environmental risk and potential enantioselective toxicity to aquatic organisms. Our study aimed to target enantioselectivity in AMP toxicity to the freshwater invertebrate Daphnia magna. Daphnids were subchronically exposed to the racemate (rac-AMP: 0.1, 1.0, and 10 µg/L) and pure enantiomers, (R)-AMP and (S)-AMP (0.1, and 1.0 µg/L, respectively), for 8 days. Morphophysiological, swimming behavior, reproductive and biochemical variables were evaluated during critical life stages (juveniles vs. adults). Some responses were context-dependent and often enantioselective, varying between racemate and enantiomers and across the life stage of the organisms. Overall, rac-AMP stimulated D. magna growth, decreased heart rate and area, affected behavior, and stimulated reproduction. The effect of enantiomers was totally or partially concordant with rac-AMP, except for swimming behavior and reproduction. Enantioselectivity was observed for body size, number of eggs/daphnia, and heart rate (steeper decrease caused by (R)-AMP on day 3). Changes in biochemical parameters were also observed: AMP caused a significant decrease in catalase activity as racemate or pure enantiomers, whereas a decrease in acetylcholinesterase activity was found only for rac-AMP. Evidence for oxidative stress was contradictory, although both enantiomers caused a significant decrease in reactive oxygen species (unlike rac-AMP). Overall, these results show that AMP can interfere in an enantioselective way with aquatic organisms at low concentrations (e.g., 0.1 µg/L), demonstrating the relevance of this kind of study to an accurate environmental risk assessment regarding medium- to long-term exposure to this psychoactive drug. Environ Toxicol Chem 2023;42:1743-1754. © 2023 SETAC.

Serum Iodine and Bromine in Chronic Hemodialysis Patients-An Observational Study in a Cohort of Portuguese Patients.

Background: Patients on chronic hemodialysis therapy are at high risk of disturbances in trace element status due to both the underlying disease and the hemodialysis process itself. Data on iodine and bromine levels in these patients are scarce. Methods: Using an ICP-MS analytical procedure, serum iodine and bromine levels were determined in a cohort (n = 57) of end-stage renal disease patients on chronic hemodialysis. The results were compared with those of a control group (n = 59). Results: Hemodialysis patients presented serum iodine levels within the normal range, slightly lower than in controls, but without reaching a statistically significant difference (67.6 ± 17.1 µg/L vs. 72.2 ± 14.8 µg/L; p = 0.1252). In contrast, serum bromine levels were much lower in patients (1086 ± 244 µg/L vs. 4137 ± 770 µg/L; p < 0.0001), at values only about 26% of the values observed in controls. Conclusions: Hemodialysis patients had normal serum iodine levels, but highly decreased serum bromine levels. The clinical significance of this finding requires further investigation, but it may be associated with sleep disturbances and fatigue that affect hemodialysis patients.

Association of trace element status in COVID-19 patients with disease severity.

Caused by the new SARS-CoV-2 coronavirus, COVID-19 (coronavirus disease 2019) evolves with clinical symptoms that vary widely in severity, from mild symptoms to critical conditions, which can even result in the patient's death. A critical aspect related to an individual response to SARS-CoV-2 infection is the competence of the immune system, and it is well known that several trace elements are essential for an adequate immune response and have anti-inflammatory and antioxidant properties that are of particular importance in fighting infection. Thus, it is widely accepted that adequate trace element status can reduce the risk of SARS-CoV-2 infection and disease severity. In this study, we evaluated the serum levels of Cu, Zn, Se, Fe, I and Mg in patients (n = 210) with clinical conditions of different severity ("mild", "moderate", "severe" and "exitus letalis", i.e., patients who eventually died). The results showed significant differences between the four groups for Cu, Zn, Se and Fe, in particular a significant trend of Zn and Se serum levels to be decreased and Cu to be increased with the severity of symptoms. For Mg and I, no differences were observed, but I levels were shown to be increased in all groups.

Midwives' interventions for reducing fear of childbirth in pregnant women: a scoping review.

OBJECTIVE: The objective of this review was to map and analyze midwives' interventions for reducing fear of childbirth in pregnant women. INTRODUCTION: Fear of childbirth is a phenomenon negatively affecting women's health and well-being before and during pregnancy. Over the past few decades, there has been growing research interest in interventions for reducing fear of childbirth in pregnant women. One of the challenges in midwifery care is to provide an appropriate model of care for pregnant women with fear of childbirth. Further research efforts are needed to identify midwives' interventions for reducing fear of childbirth in pregnant women and to examine their characteristics. INCLUSION CRITERIA: This scoping review considered studies that included midwives' interventions for reducing fear of childbirth in pregnant women. Specifically, interventions were led and/or implemented by midwives during the antenatal period, and integrating all possible midwifery practice settings. Quantitative, qualitative, and mixed methods studies were included. This review also considered systematic reviews, text and opinion papers, and conference abstracts. METHODS: The JBI methodology for conducting scoping reviews was used. Published and unpublished literature in English, Portuguese, and Spanish from January 1981 to October 2020 was included. MEDLINE (PubMed), CINAHL Complete, APA PsycINFO, Scopus, Embase, Web of Science, SciELO, MedicLatina, Academic Search Complete, ERIC, Psychology and Behavioral Sciences Collection, and the Cochrane Library databases were searched. Searches for gray literature were also undertaken on the Repositório Científico de Acesso Aberto de Portugal, ProQuest Dissertations and Theses, British Library EThOS, OvidSP Resource Center, Banco de Teses da CAPES, and OpenGrey. A three-step search strategy was followed, and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis extension for Scoping Reviews checklist was used. Two independent reviewers extracted the data using a data extraction tool developed specifically for this scoping review. RESULTS: A total of 3704 articles were identified and screened, of which 34 articles were included. The majority of studies had been published in the past 10 years (88%) in Scandinavian countries or Australia (79%). Several midwives' antenatal interventions were found, such as midwife-led team models of care. Midwives played a facilitator role that varied across the included studies. In 20 studies (59%), midwives led and implemented the interventions alone ( n   =  13; 38%) or with the participation of other health professionals ( n   =  7; 21%). In the remaining 14 studies (41%), midwives were part of a multidisciplinary team that included different health professionals (mainly obstetricians and psychologists) who had been involved in delivering interventions alongside midwives or with minor participation from midwives. Counseling ( n   =  12; 35%) and psychoeducation ( n   =  8; 24%) were the most common midwife interventions for reducing fear of childbirth in pregnant women. CONCLUSIONS: Midwives working across their full scope of practice play a pivotal role in reducing fear of childbirth, which may explain the variety of midwives' antenatal interventions. Reducing fear of childbirth in pregnant women and promoting normal childbirth as a positive experience are key features of midwives' interventions, which should include women's empowerment measures. Evidence-based midwife-led intervention programs for pregnant women with fear of childbirth should be designed and tested to improve clinical practice as well as women's reproductive outcomes and perinatal experiences.

Pollution status and risk assessment of trace elements in Portuguese water, soils, sediments, and associated biota: a trend analysis from the 80s to 2021.

Pollution of water bodies and sediments/soils by trace elements remains a global threat and a serious environmental hazard to biodiversity and human's health. Globalization and industrialization resulted in the increase and availability of these substances in the environment posing unpredictable adverse effects to living organisms. To determine pollution status and risk contamination by trace elements, data available in the literature of the last 40 years on trace elements occurrence in three environmental matrices (water bodies, sediments/soils, and biota) from Continental Portugal were collected (about 90 studies). Data were compared to water and sediment quality guidelines to assess potential ecological risks. Most environmentally relevant hazardous elements include Zn, Cu, Cd, Pb, and As. Various studies found trace elements at levels higher than those considered safe by environmental guidelines. In surface waters, Al, Zn, Se, and Ag were found above aquatic life limits in about 60% of the reviewed papers, while Cu, Zn, and As exceed those values in more than 60% of mining waters. Hg and Cd in sediments from mining areas exceeded aquatic life limits and potential ecological risk showed extremely high risk for most of the elements. The data compiled in this review is very heterogenous, varying in terms of sampling schemes, trace elements analysed, and spatiotemporal settings. This heterogenicity leads to data differences that make meaningful comparisons difficult. Nevertheless, the compilation of scattered environmental spatial and temporal trace elements data, of either natural sources or human activity as well as the ultimate effect on biological systems, is of the upmost importance to broaden its knowledge, risk assessment, and implementation of mitigation measures.

Trace Elements as Contaminants and Nutrients.

Knowledge about trace elements has evolved remarkably in recent decades, both in terms of their metabolism and their functions [...].

Metallic Nanoparticles in the Food Sector: A Mini-Review.

Nanomaterials, and in particular metallic nanoparticles (MNPs), have significantly contributed to the production of healthier, safer, and higher-quality foods and food packaging with special properties, such as greater mechanical strength, improved gas barrier capacity, increased water repellency and ability to inhibit microbial contamination, ensuring higher quality and longer product shelf life. MNPs can also be incorporated into chemical and biological sensors, enabling the design of fast and sensitive monitoring devices to assess food quality, from freshness to detection of allergens, food-borne pathogens or toxins. This review summarizes recent developments in the use of MNPs in the field of food science and technology. Additionally, a brief overview of MNP synthesis and characterization techniques is provided, as well as of the toxicity, biosafety and regulatory issues of MNPs in the agricultural, feed and food sectors.

Assessment of effluents quality through ecotoxicological assays: evaluation of three wastewater treatment plants with different technologies.

The water quality of the effluents is mainly focused on physicochemical and microbiological parameters. However, the ecotoxicological assessments are crucial to ensure an effective water quality of the effluents. This work aims to assess the ecotoxicity of effluents originated from WWTPs with different wastewater treatment technologies. For that, effluent samples from three WWTPs with different treatment processes were seasonally collected. Physicochemical parameters were determined, the toxicity towards daphnia, protozoan, and microalgae organisms was evaluated, and data correlated. Toxicity assays showed different susceptibility of the organisms to the effluents and that toxicity is dependent on the season and wastewater treatment technology. No toxicity was observed to daphnia in winter and spring, but ~100% of mortality was observed in effluent from WWTP A in summer. Growth inhibition was observed for both protozoan and microalgae for all effluents and in all seasons with highest values in spring in WWTP C (~80%) for the protozoan while the highest microalgae growth inhibition percentage was observed for WWTP B in both spring (~80%) and summer (~80%). These results show that effluents might have negative impacts into their receiving water systems and highlight that a global assessment of effluent quality should include ecotoxicological assays to complement physicochemical and microbiological data for an operative environmental management of wastewater treatment plants.

Prevención del trauma perineal: una revisión integradora de la literatura Prevenção do traumatismo perineal: uma revisão integrativa da literatura / Prevenção do traumatismo perineal: uma revisão integrativa da literatura / Trauma perineal prevention: an integrative literature review

Este artículo describe las estrategias que pueden ser desarrolladas por la matrona con el objetivo de mantener la integridad del perineo materno, durante la fase activa del segundo periodo del trabajo de parto. Objetivo: Determinar la evidencia disponible sobre las intervenciones de la matrona para la prevención del trauma perineal. Método: Identificación de artículos incorporando las evidencias científicas sobre la prevención del trauma perineal, recurriendo a un conjunto de bases de datos de la salud: Medline, Elsevier, Nursing Reference, Cochrane Database of Systematic Reviews, resultante en 14 artículos. Resultados/Discusión: La actuación de la matrona en la prevención del trauma perineal debe seguir un conjunto secuencial de intervenciones: incentivar el ejercicio físico moderado, tres veces por semana, durante el embarazo; incentivar a la mujer para la realización del masaje perineal, desde la 30ª semana de gestación; promover la restricción de la manipulación perineal durante el trabajo de parto, haciendo solamente masaje suave, alentando el tirón espontáneo y el cambio de posición de la madre y, además, proceder a la aplicación de gasas calientes en el perineo, y preferir el apoyo perineal simple cuando se aplica la maniobra de Ritgen. En todo el proceso, promover el empoderamiento de la mujer mediante el apoyo y la confianza. Conclusión: Las intervenciones son señaladas como beneficiosas en la prevención del trauma perineal. No obstante, su aplicación exige más evidencia, así como una efectiva divulgación de sus resultados por parte de los equipos multidisciplinares y de la comunidad con la presentación de los beneficios para la salud de la mujer, la familia y la sociedad (AU)

Este artigo descreve as estratégias que podem ser desenvolvidas pela parteira na preservação do trauma perineal, durante o segundo período do trabalho de parto. Objetivo: Determinar a evidência científica disponível sobre as intervenções da parteira para prevenir o trauma perineal. Método: Identificação de artigos incorporando as evidências científicas sobre a prevenção do trauma perineal utilizando as bases de dados: Medline, Elsevier, Nursing Reference, Cochrane Database of Systematic Reviews, resultando numa amostra de 14 artigos. Resultados/Discussão: A intervenção da parteira na prevenção do trauma perineal deve atender a um conjunto sequencial de intervenções: Incentivar o exercício físico moderado, no mínimo três vezes por semana, desde que constatada a gravidez; Educar e incentivar a mulher à realização da massagem perineal, desde a 30ª semana de gestação; Promover a mudança postural ao longo do trabalho de parto, com possibilidade de deambulação; Incentivar e apoiar a mulher ao puxo espontâneo, ao longo da fase ativa do segundo período do trabalho de parto; Promover a restrição da manipulação perineal, permitindo a adaptação, lenta e gradual, dos tecidos à apresentação fetal; Proceder à aplicação de compressas quentes no períneo, durante o segundo período do trabalho de parto; Efetuar massagem perineal suave, usando um lubrificante; Preferir o apoio perineal simples aquando da aplicação da manobra de Ritgen, em prol da sua versão modificada, sendo esta mais interventiva. Conclusões: As intervenções são apontadas como contributos na prevenção do trauma perineal. Contudo, a sua aplicação exige a disponibilidade de mais evidência, bem como uma efetiva divulgação dos seus resultados junto das equipas multidisciplinares e da comunidade, com apresentação dos ganhos em saúde para a mulher família e sociedade (AU)

This article describes the strategies that can be developed by the midwife in order to maintain the integrity of the maternal perineum and prevent the practice of episiotomy during the active phase of the second period of labor. Objective: To assess the available scientific evidence about the midwife’s interventions in order to prevent perineal trauma. Method: Identification of articles that incorporate scientific evidence on preventing perineal trauma, using the following databases: Medline, Elsevier, Nursing Reference, Cochrane Database of Systematic Reviews, which resulted in 14 articles. Results/Discussion: The performance of the midwife in the prevention of perineal trauma must follow a sequential set of interventions: to encourage moderate exercise three times a week during pregnancy; to encourage women to perform the perineal massage from the 30th week of pregnancy; to promote the restriction of perineal manipulation during labor, doing only a gentle massage, encouraging spontaneous pushing, changing the position of the mother, applying hot dressings in the perineum, and preferring a simple perineal support when Ritgen maneuver is applied. During all this process, to promote the empowerment of the mother, by giving support and confidence. Conclusion: The aforementioned interventions are referred as beneficial to the prevention of perineal trauma and to the practice of episiotomy. However, their application requires more evidence, as well as an effective divulgation of the results by the multidisciplinary teams and community with the presentation of the benefits to the health of women, family and society (AU)

Anthropogenic pressure in a Portuguese river: Endocrine-disrupting compounds, trace elements and nutrients.

Natural organic compounds such as phytoestrogens and phytosterols found in various plants, as well as mycotoxins produced by fungi, can be found in aquatic environments. The aim of this study was to investigate the occurrence of three different classes of natural estrogenic compounds, i.e., phytoestrogens, phytosterols and mycotoxins, in estuarine water samples from the Ave River estuary. For that, water samples were collected at five sampling points distributed along the estuary at low tide, during 1 year, processed by solid-phase extraction (SPE) and analyzed by gas chromatography coupled to mass spectrometry (GC-MS). To correlate the presence of phytoestrogens and phytosterols in the estuarine water, local flora was collected on riverside. Trace elements content and physicochemical parameters such as nutrients and dissolved oxygen were also determined seasonally at each sampling point, to give insights for the evaluation of water quality and anthropogenic pressure. Both phytoestrogens and phytosterols showed a seasonal variation, with the highest values observed in spring and summer and the lowest in winter. Daidzein (DAID) was found up to 404.0 ng L(-1) in spring and coumestrol (COUM) was found up to 165.0 ng L(-1) in summer. The mycotoxin deoxynivalenol (DON) was ubiquitously determined with values ranging from 59.5 to 642.4 ng L(-1). Nutrients and metals distribution and concentration varied among sampling stations and seasons. This study revealed for the first time the presence of mycotoxins, various classes of phytoestrogens and stigmasterol (STG) in estuarine water from the Ave River (Portugal), and the evaluation of the water quality confirmed that this estuary is still highly impacted by anthropogenic activities.

Trace Elements in Ambient Air at Porto Metropolitan Area-Checking for Compliance with New European Union (EU) Air Quality Standards.

Because of the scientific evidence showing that arsenic (As), cadmium (Cd), and nickel (Ni) are human genotoxic carcinogens, the European Union (EU) recently set target values for metal concentration in ambient air (As: 6 ng/m(3), Cd: 5 ng/m(3), Ni: 20 ng/m(3)). The aim of our study was to determine the concentration levels of these trace elements in Porto Metropolitan Area (PMA) in order to assess whether compliance was occurring with these new EU air quality standards. Fine (PM2.5) and inhalable (PM10) air particles were collected from October 2011 to July 2012 at two different (urban and suburban) locations in PMA. Samples were analyzed for trace elements content by inductively coupled plasma-mass spectrometry (ICP-MS). The study focused on determination of differences in trace elements concentration between the two sites, and between PM2.5 and PM10, in order to gather information regarding emission sources. Except for chromium (Cr), the concentration of all trace elements was higher at the urban site. However, results for As, Cd, Ni, and lead (Pb) were well below the EU limit/target values (As: 1.49 ± 0.71 ng/m(3); Cd: 1.67 ± 0.92 ng/m(3); Ni: 3.43 ± 3.23 ng/m(3); Pb: 17.1 ± 10.1 ng/m(3)) in the worst-case scenario. Arsenic, Cd, Ni, Pb, antimony (Sb), selenium (Se), vanadium (V), and zinc (Zn) were predominantly associated to PM2.5, indicating that anthropogenic sources such as industry and road traffic are the main source of these elements. High enrichment factors (EF > 100) were obtained for As, Cd, Pb, Sb, Se, and Zn, further confirming their anthropogenic origin.

Application of lactate amperometric sol-gel biosensor to sequential injection determination of L-lactate.

This work describes the construction and evaluation of lactate sol-gel biosensors to accomplish the determination of lactate in pharmaceutical products. Lactate oxidase was incorporated in a porous sol-gel film placed onto a platinum-based electrode. Acid and basic catalysis were assessed. When coupled to a sequential injection system (SIA) the biosensor, based on (3-aminopropyl)trimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl-trimethoxysilane, deionised water, polyethylene glycol 6000 and acid catalyst, presented a range of linearity of 5x10(-5) to 5x10(-3)M. The analytical usefulness of the developed biosensor was evaluated through analysis of commercial pharmaceutical products containing lactate with a sampling rate of 40 samples h(-1). The enzyme remained active for at least 30 days, enabling about 700 determinations without sensitivity decrease.

Potentiometric behaviour of ion selective electrodes based on iron porphyrins: the influence of porphyrin substituents on the response properties and analytical determination of diclofenac in pharmaceutical formulations.

The potentiometric response characteristics of diclofenac selective electrodes based on Fe(III) tetraphenylporphyrin-chloride (Fe(III)TPP-Cl) and Fe(III) tetrakis(pentafluorophenyl)porphyrin-chloride (Fe(III)TPFPP-Cl) in different mediator solvents and ionic additives are compared. The sensitivity, working range, detection limit, response mechanism, and selectivity of the membrane sensor show a significant dependence on the type of carrier substituent and on the pH value of the sample solution. Studies performed with different amounts of cationic additive (tetra-n-octylammoniumbromide (TOABr)) and anionic additive (sodium tetraphenylborate (NaTPB)) in the membranes allowed the determination of the potentiometric mechanism of action of the used metalloporphyrins. For the analysis of real samples, Fe(III)TPFPP-Cl (type G), prepared in o-NPOE, incorporating 10 mol% of TOABr, was used. This potentiometric unit presented a linear response towards diclofenac concentrations between 10(-5) and 10(-2)mol l(-1) ( I=0.1 mol l(-1)) and slopes of about -59 mV dec(-1), exhibiting a response time of 10s in a buffered solution of ammonia-ammonium sulphate with pH 9.9. The potentiometric analysis of sodium diclofenac in pharmaceutical formulations was carried out by direct potentiometry and the obtained results were compared to those provided by HPLC, presenting relative errors inferior to 1.0%.

Construction and evaluation of PVC and sol-gel sensor membranes based on Mn(III)TPP-Cl. Application to valproate determination in pharmaceutical preparations.

The construction and general performance of new valproate-selective electrodes based on manganese(III) tetraphenylporphyrin [Mn(III)TPP-Cl], as an ionophore, are presented. The ionophore was incorporated into PVC and ceramic membranes (sol-gel) based on methyltriethoxysilane. The influence of membrane composition and pH and the effect of lipophilic cationic and anionic additives in PVC membranes were investigated concerning their influence on the slope, response time, selectivity and lifetime of the electrodes. The PVC membrane without additive and the sol-gel membrane presented slopes and practical limits of detection of -60.8 mV dec(-1) and 5x10(-6) mol l(-1) and -60.3 mV dec(-1) and 1x10(-4) mol l(-1), respectively. The sol-gel membranes displayed higher selectivity for valproate when compared with PVC membranes. These two types of electrodes were coupled to a sequential-injection analysis (SIA) system for the direct determination of valproate in pharmaceutical formulations. The association of Mn(III)TPP-Cl with the sol-gel support inserted in a SIA system provided potentiometric sensors with an analytical range of 1x10(-3)-5x10(-2) mol l(-1), with a sample rate of 55 samples per hour and a sample and carrier consumption of 140 and 2,500 microl per determination, respectively.

Ion selective electrodes for penicillin-G based on Mn(III)TPP-Cl and their application in pharmaceutical formulations control by sequential injection analysis.

The work describes the construction, evaluation and analytical application of ion selective electrodes sensitive to penicillin-G antibiotics for pharmaceutical products analysis. Different types of polymeric membranes based on PVC (poly(vinyl chloride)) and EVA (ethyl-vinyl-acetate), without internal reference solution, were prepared using 5,10,15,20-tetraphenylporphyrinate (TPP) manganese(III) (Mn(III)TPP-Cl) as electroactive material. Different additives such as tetra-n-octylammoniumbromide (cationic additive) and sodium tetraphenylborate (anionic additive) were incorporated into the membranes to evaluate their influence on electrodes performance. The comparison of the developed detectors was based on general analytical characteristics, selectivity and lifetime. To accomplish the analysis of real samples, two selective membranes composed of 33.0% (w/w) of PVC, 66.0% (w/w) of o-NPOE and 1.0% (w/w) of Mn(III)TPP-Cl (type A) and 33.0% (w/w) of PVC, 66.0% (w/w) of o-NPOE, 1.0% (w/w) of Mn(III)TPP-Cl and 10% mol (relative to the molar concentration of Mn(III)TPP-Cl) of sodium tetraphenylborate (type B) were used. Type A electrode presented a linear response between 2 x 10(-5) and 10(-1) moll(-1) for penicillin-G, a slope of about -59 mVdec(-1) and a reproducibility of about +/-0.5 mVday(-1), while type B exhibited a linear response between 5 x 10(-5) and 10(-1) moll(-1) for penicillin-G, a slope of about -61 mVdec(-1) and a reproducibility of about +/-0.3 mV day(-1). The potentiometric analysis of penicillin-G in pharmaceutical products was carried out by direct potentiometry and the results obtained were compared with those provided by the HPLC reference method. These membranes (type A and type B) were used to prepare tubular electrodes that were coupled to a sequential injection system (SIA) and presented a linear range between 2 x 10(-4) and 1 x 10(-2) moll(-1) and slopes of -59.3 +/- 0.8 and -57.3 +/- 1.2 mVdec(-1), respectively. The tubular electrode constructed using type B membrane (type TB) was used to carry out the potentiometric analysis of penicillin-G in pharmaceutical formulations. The proposed procedure enabled relative errors between 0.1% and 1.2% (n = 4) and a sampling-rate of about 25 samples per h.

Sequential injection analysis of chloride and nitrate in waters with improved accuracy using potentiometric detection.

Accurate simultaneous analysis of different anionic species using ion-selective electrodes (ISEs) can be achieved even for non-specific sensors by resorting to an ordinary least squares multiple regression in the vicinity of the predicted concentrations. In this work the potentialities of this approach are evidenced by the determination of nitrate and chloride in synthetic and real water samples in which chloride concentration was significantly higher than nitrate. An AgCl/Ag(2)S electrode based on a homogeneous crystalline membrane together with a PVC electrode based on tert-octylammonium bromide dissolved in dibutylphthalate were used as potentiometric detectors for chloride and nitrate, respectively. For the implementation of the procedure, an automatic system based on sequential injection analysis was used. The results obtained by the standard addition method were biased for low concentrations of nitrate and were dependant on the relative proportion of NO(3)(-)/Cl(-). The results obtained by the proposed methodology for chloride determination were slightly better when compared to those obtained by the standard addition method. In relation to nitrate determination, the proposed methodology yielded values with a relative root mean square error of prediction (RRMSEP) of 2.8%, while for standard addition calibration, mean error values were approximately 12.1%.

Amperometric biosensor based on monoamine oxidase (MAO) immobilized in sol-gel film for benzydamine determination in pharmaceuticals.

The development and application of a flow-through amperometric biosensor for benzydamine determination in anti-inflammatory drugs is described. The biosensor was obtained by physical entrapment of monoamine oxidase in a sol-gel film applied on platinum or carbon paste conducting support. The sol-gel membranes were prepared using an optimum concentration of 3-aminopropyltriethoxy silane, 2-(3,4-epoxycyclohexyl)ethyl-trimethoxy silane, double distilled water saturated with polyethylene glycol 6000 and HCl. The developed biosensors were incorporated in a single channel flow injection system to enable the determination of benzydamine in the concentration range of 0.05-2.5 mmol l(-1) (with platinum based electrode) or within 0.1-2.5 mmol l(-1) (carbon paste based electrode). The operational stability of the bioanalytical system developed was about 3 months permitting approximately 4700 substrate measurements. The flow injection system developed enables a sampling rate of 20-25 samples h(-1) and relative S.D. of results less than 4%. The analytical usefulness of the proposed procedure was evaluated through analysis of commercial pharmaceutical products containing benzydamine, available on the Portuguese market. The results obtained did not differ significantly from the values resulting from analysis of the same products by the method described in the BP Pharmacopoeia.

Ion-selective electrodes based on metalloporphyrins for gibberellic acid determination in agricultural products.

This work describes the construction, evaluation and analytical application of electrodes selective to the gibberellate anion for the determination of gibberellic acid in agricultural products. Several types of PVC membrane electrodes without internal reference solution were prepared using the manganese(III) complex of meso-tetraphenylporphyrin (TPP) as ionophore and dibutyl phthalate (DBP), as plasticizer. The incorporation of lipophilic chemical species as additives, was also carried out aiming the evaluation of the response characteristics of the electrodes. To accomplish the analysis of commercial agricultural products a selective membrane composed of 28.0% (w/w) of PVC, 66.0% (w/w) of plasticizer and 6% (w/w) of ionophore was used, with no additive. This potentiometric unit presented a linear response between 10(-4) and 10(-1) mol L(-1) in gibberellate, a slope of about -69 mV dec(-1) and a reproducibility of about +/-1 mV day(-1). The potentiometric analysis of gibberellic acid in commercial products was carried out by direct potentiometry and the results obtained were compared with those provided by HPLC.

Design and development of a multichannel potentiometer for monitoring an electrode array and its application in flow analysis.

A versatile potentiometer that works with electrode arrays in flow injection and/or monosegmented flow systems is described. The potentiometer is controlled by a microcomputer that allows individual, sequential multiplexed or random accesses to eight electrodes while employing only one reference electrode. The instrument was demonstrated by monitoring an array of seven flow-through ion-selective electrodes for Ag+ and for three electrodes for Cl(-), Ca2+ and K+. The figures of merit of the individual and multiplexed (summed) readings of the electrode array were compared. The absolute standard deviation of the measurements made by summing the potential of two or more electrodes was maintained constant, thus improving the precision of the measurements. This result shows that an attempt to combine the signals of the electrodes to produce a more intense signal in the Hadamard strategy is feasible and accompanied by a proportional improvement in the precision of individual measurements. The preliminary tests suggest that the system can allow for 270 determinations per hour, with a linear range from 1.0 x 10(-2) to 1.0 x 10(-4) mol l(-1) for the three different analytes. Detection limits were estimated as 3.1 x 10(-5), 3.0 x 10(-6) and 1.0 x 10(-5) mol l(-1) for Cl(-), Ca2+ and K+, respectively.

Application of amperometric sol-gel biosensor to flow injection determination of glucose.

A glucose biosensor with enzyme immobilised by sol-gel technology was constructed and evaluated. The glucose biosensor reported is based on encapsulated GOX within a sol-gel glass, prepared with 3-aminopropyltriethoxy silane, 2-(3,4-epoxycyclohexyl)-ethyltrimetoxy silane and HCl. A flow system incorporating the amperometric biosensor constructed was developed for the determination of glucose in the 1x10(-4)-5x10(-3) moll(-1) range with a precision of 1.5%. The results obtained for the analysis of electrolytic solution for iv administration and human serum samples showed good agreement between the proposed method and the reference procedure, with relative error <5%.